Patent Publication Number: US-2022218435-A1

Title: Systems and methods for integrating imagery captured by different imaging modalities into composite imagery of a surgical space

Description:
RELATED APPLICATIONS 
     The present application claims priority to U.S. Provisional Patent Application No. 62/855,755, filed on May 31, 2019, and entitled “SYSTEMS AND METHODS FOR INTEGRATING IMAGERY CAPTURED BY DIFFERENT IMAGING MODALITIES INTO COMPOSITE IMAGERY OF A SURGICAL SPACE,” the contents of which are hereby incorporated by reference in their entirety. 
    
    
     BACKGROUND INFORMATION 
     During a surgical procedure, an endoscope may be used to capture endoscopic imagery of a surgical space. The endoscopic imagery may be presented to a surgeon by way of a display device so that the surgeon may visualize the surgical space while performing the surgical procedure. An endoscope is one imaging modality that is used to capture imagery of the surgical space. 
     In some scenarios, one or more additional imaging modalities may be used to capture additional imagery of the surgical space that may also be presented to the surgeon. For example, an ultrasound scan, a computerized tomography (CT) scan, and a magnetic resonance imaging (MRI) scan are other imaging modalities that may be used to capture imagery of the surgical space. 
     Imagery captured by different imaging modalities may be presented to the surgeon such that the surgeon may visualize the surgical space while performing the surgical procedure. However, there remains room to improve technologies for processing and presenting imagery captured by different surgical space imaging modalities. 
     SUMMARY 
     The following description presents a simplified summary of one or more aspects of the systems and methods described herein. This summary is not an extensive overview of all contemplated aspects and is intended to neither identify key or critical elements of all aspects nor delineate the scope of any or all aspects. Its sole purpose is to present one or more aspects of the systems and methods described herein as a prelude to the detailed description that is presented below. 
     An exemplary system includes a memory storing instructions and a processor communicatively coupled to the memory and configured to execute the instructions to determine an image render viewpoint from which to render an image of a surgical space; determine, from a perspective of the image render viewpoint, a position of an augmentation region relative to the surgical space, the augmentation region selectively movable relative to the surgical space; generate a composite image of the surgical space from the perspective of the image render viewpoint and based on the determined position of the augmentation region relative to the surgical space, and direct a display device to display the composite image. The composite image may include: the augmentation region at the determined position of the augmentation region relative to the surgical space; outside the augmentation region, a representation of a first portion of the surgical space as captured by a first imaging modality; and inside the augmentation region, a representation of a second portion of the surgical space as captured by a second imaging modality, the representation of the second portion of the surgical space generated based on first imagery of the surgical space captured by the first imaging modality and second imagery of the surgical space captured by the second imaging modality. 
     Another exemplary system includes a memory storing instructions and a processor communicatively coupled to the memory and configured to execute the instructions to access first imagery of a surgical space captured by a first imaging modality; access second imagery of the surgical space captured by a second imaging modality, the second imaging modality different from the first imaging modality; generate a composite image of the surgical space based on the first imagery captured by the first imaging modality and the second imagery captured by the second imaging modality; and direct a display device to display the composite image. The composite image may include: a representation of a first portion of the surgical space as captured by the first imaging modality, the representation of the first portion of the surgical space generated based on the first imagery captured by the first imaging modality; an augmentation region integrated within the representation of the first portion of the surgical space; and, inside the augmentation region, a representation of a second portion of the surgical space as captured by the second imaging modality, the representation of the second portion of the surgical space including a composition of imagery of the surgical space captured by the second imaging modality modified by a feature of imagery of the surgical space captured by the first imaging modality. 
     An exemplary method includes a computing system determining an image render viewpoint from which to render an image of a surgical space; determining, from a perspective of the image render viewpoint, a position of an augmentation region relative to the surgical space, the augmentation region selectively movable relative to the surgical space; generating a composite image of the surgical space from the perspective of the image render viewpoint and based on the determined position of the augmentation region relative to the surgical space; and directing a display device to display the composite image. The composite image may include: the augmentation region at the determined position of the augmentation region relative to the surgical space; outside the augmentation region, a representation of a first portion of the surgical space as captured by a first imaging modality; and, inside the augmentation region, a representation of a second portion of the surgical space as captured by a second imaging modality, the representation of the second portion of the surgical space generated based on first imagery of the surgical space captured by the first imaging modality and second imagery of the surgical space captured by the second imaging modality. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings illustrate various embodiments and are a part of the specification. The illustrated embodiments are merely examples and do not limit the scope of the disclosure. Throughout the drawings, identical or similar reference numbers designate identical or similar elements. 
         FIG. 1  illustrates an exemplary imaging modality integration system according to principles described herein. 
         FIG. 2  illustrates the imaging modality integration system of  FIG. 1  configured to generate composite imagery of a surgical space based on imagery captured by different imaging modalities according to principles described herein. 
         FIG. 3  illustrates an exemplary composite image of a surgical space according to principles described herein. 
         FIG. 4  illustrates an exemplary positioning of an image render viewpoint and an augmentation region relative to a surgical space according to principles described herein. 
         FIG. 5A  illustrates an exemplary real workspace included in a surgical space according to principles described herein. 
         FIG. 5B  illustrates an exemplary endoscopic image of the real workspace of  FIG. 5A  according to principles described herein. 
         FIG. 5C  illustrates an exemplary slope image extracted from the endoscopic image of  FIG. 5B  according to principles described herein. 
         FIG. 6A  illustrates an exemplary virtual workspace according to principles described herein. 
         FIG. 6B  illustrates an exemplary image of the virtual workspace of  FIG. 6A  according to principles described herein. 
         FIG. 6C  illustrates an exemplary mask image according to principles described herein. 
         FIG. 7  illustrates an exemplary composite image of a surgical space according to principles described herein. 
         FIG. 8  illustrates an exemplary computer-assisted surgical system according to principles described herein. 
         FIG. 9  illustrates an exemplary method according to principles described herein. 
         FIG. 10  illustrates an exemplary computing device according to principles described herein. 
     
    
    
     DETAILED DESCRIPTION 
     Systems and methods for integrating imagery captured by different imaging modalities into composite imagery of a surgical space are described herein. In certain examples, an imaging modality integration system may be configured to integrate imagery captured by different imaging modalities by generating composite imagery that includes integrated representations of a surgical space as captured by multiple different imaging modalities. For example, the imaging modality integration system may be configured to generate a composite image that includes a representation of a first portion of the surgical space as captured by a first imaging modality and an integrated representation of a second portion of the surgical space as captured by a second imaging modality. The imaging modality integration system may be configured to integrate the representation of the second portion of the surgical space with the representation of the first portion of the surgical space in a manner that augments imagery of the surgical space as captured by one imaging modality (e.g., endoscopic imaging) with imagery of the surgical space as captured by a second imaging modality (e.g., ultrasound, CT, or MRI imaging). 
     In certain examples, the imaging modality integration system may be configured to generate the representation of the second portion of the surgical space based on first imagery of the surgical space captured by the first imaging modality and second imagery of the surgical space captured by the second imaging modality. For example, the representation of the second portion of the surgical space may be generated to include a composition of the second imagery of the surgical space and a feature of the first imagery of the surgical space. For instance, to produce the representation of the second portion of the surgical space, the second imagery of the surgical space may be combined with slope imagery representing gradient information extracted from the first imagery of the surgical space. Such a composition may produce a visually realistic appearance (e.g., an appearance of depth that facilitates depth perception) of the representation of the second portion of the surgical space integrated with the representation of the first portion of the surgical space. In certain examples, the composition is generated based on actual, organic colors of the first imagery and the second imagery, without using artificial or non-photorealistic colors. Examples of how the representation of the second portion of the surgical space may be generated and integrated with the representation of the first portion of the surgical space are described herein. 
     In certain examples, the first imaging modality may include endoscopic imaging (e.g., imaging by an endoscope) that captures endoscopic imagery of surface anatomy included in a surgical space, and the second imaging modality (e.g., ultrasound, CT, or MRI imaging) may capture imagery of subsurface anatomy included in the surgical space. In such examples, the imaging modality integration system may be configured to generate composite imagery that includes a representation of a first portion of the surgical space that is generated based on the endoscopic imagery of surface anatomy as captured by an endoscope and an integrated representation of a second portion of the surgical space that is generated based on the imagery of the subsurface anatomy as captured by the second imaging modality. The representation of the second portion of the surgical space may be generated to include a composition of the imagery of the subsurface anatomy as captured by the second imaging modality and a feature of the endoscopic imagery of the surface anatomy as captured by the endoscope. For instance, the imagery of the subsurface anatomy as captured by the second imaging modality may be combined with slope imagery extracted from the endoscopic imagery to produce the representation of the second portion of the surgical space. Such a composition may produce a visually realistic appearance (e.g., an appearance of depth that facilitate depth perception) of the imaged subsurface anatomy relative to the imaged surface anatomy when the representations are integrated in a composite image. 
     In certain examples, the second portion of the surgical space may be dynamically selected by way of user input to a computer-assisted surgical system or automatically by the computer-assisted surgical system (e.g., by performing an automatic scan). For example, the imaging modality integration system may be configured to provide an augmentation region (e.g., a virtual object representing an augmentation region) that is selectively movable relative to the surgical space based on user input to the computer-assisted surgical system or based on automatic movement controlled by the computer-assisted surgical system (e.g., as part of an automatic scan). At any given time during a surgical procedure, the imaging modality integration system may be configured to determine a position of the augmentation region relative to the surgical space and to use the determined position of the augmentation region relative to the surgical space to determine the first and second portions of the surgical space to be used to generate a composite image of the surgical space. For example, the imaging modality integration system may be configured to identify the first portion of the surgical space to be a portion of the surgical space that is outside of the augmentation region from a perspective of an image render viewpoint, and to identify the second portion of the surgical space to be a portion of the surgical space that is inside the determined position of the augmentation region from the perspective of the image render viewpoint. The imaging modality integration system may use the identified first and second portions of the surgical space to generate a composite image of the surgical space. As described herein, the composite image may include integrated representations of the first and second portions of the surgical space as respectively captured by first and second imaging modalities. 
     To illustrate an example, the imaging modality integration system may be configured to determine an image render viewpoint from which to render an image of a surgical space, determine, from a perspective of the image render viewpoint, a position of an augmentation region relative to the surgical space, and generate a composite image of the surgical space from the perspective of the image render viewpoint and based on the determined position of the augmentation region relative to the surgical space such that the composite image includes: the augmentation region (e.g., a representation of the augmentation region) at the determined position of the augmentation region relative to the surgical space; outside the augmentation region, a representation of a first portion of the surgical space as captured by a first imaging modality; and, inside the augmentation region, a representation of a second portion of the surgical space as captured by a second imaging modality. The representation of the second portion of the surgical space may be generated in any of the ways described herein and may be based on first imagery of the surgical space captured by the first imaging modality and second imagery of the surgical space captured by the second imaging modality. 
     Systems and methods described herein may provide various advantages and benefits. For example, systems and methods described herein may integrate imagery captured by different imaging modalities into composite imagery of a surgical space in a manner that produces, within the composite imagery, an integrated and visually realistic appearance of imagery of the surgical scene as captured by the different imaging modalities. Systems and methods described herein may present the generated composite imagery to a user of a computer-assisted surgical system, such as a surgeon utilizing the computer-assisted surgical system to perform a surgical procedure. The presented composite imagery may be visually realistic and intuitive to the surgeon, may reduce the complexity of the surgical procedure for the surgeon (e.g., by eliminating the need for the surgeon to mentally align imagery of the surgical space that is presented separately in a non-integrated manner), may allow the surgeon to concurrently, conveniently, and intuitively visualize surface and subsurface anatomy integrated in composite imagery, and/or may allow the surgeon to provide input to conveniently and dynamically select a portion of a surgical space that is to be augmented such that the selected portion may be viewed using a different imaging modality than is used to view another portion of the surgical space (e.g., by selecting a portion of the surgical space at which imagery of subsurface anatomy is displayed as an augmentation to imagery of surface anatomy being displayed). Additionally, composite imagery that is generated based on actual, organic colors of captured imagery, without using artificial or non-photorealistic colors, may be more realistic in appearance (e.g., facilitate better depth perception) compared to composite imagery that is generated based on artificial or non-photorealistic colors. 
     These and other advantages and benefits of systems and methods described herein will be made apparent herein. 
       FIG. 1  illustrates an exemplary imaging modality integration system  100  (“system  100 ”) configured to integrate imagery captured by different imaging modalities, including by using the captured imagery to generate composite imagery that includes integrated representations of portions of a surgical space as captured by the different imaging modalities. System  100  may be included in, implemented by, or connected to one or more components of a computer-assisted surgical system. For example, system  100  may be implemented by one or more components of a computer-assisted surgical system. As another example, system  100  may be implemented by a stand-alone computing system communicatively coupled to a computer-assisted surgical system. An exemplary computer-assisted surgical system is described further below. 
     As shown in  FIG. 1 , system  100  may include a storage facility  102  and a processing facility  104  selectively and communicatively coupled to one another. Each of facilities  102  and  104  may include or be implemented by one or more physical computing devices including hardware and/or software components such as processors, memories, storage drives, communication interfaces, instructions stored in memory for execution by the processors, and so forth. Although facilities  102  and  104  are shown to be separate facilities in  FIG. 1 , facilities  102  and  104  may be combined into fewer facilities, such as into a single facility, or divided into more facilities as may serve a particular implementation. In some examples, each of facilities  102  and  104  may be distributed between multiple devices and/or multiple locations as may serve a particular implementation. 
     Storage facility  102  may maintain (e.g., store) executable data used by processing facility  104  to perform one or more of the operations described herein. For example, storage facility  102  may store instructions  106  that may be executed by processing facility  104  to perform one or more of the operations described herein. Instructions  106  may be implemented by any suitable application, software, code, and/or other executable data instance. Storage facility  102  may also maintain any data received, generated, managed, used, and/or transmitted by processing facility  104 . 
     Processing facility  104  may be configured to perform (e.g., execute instructions  106  stored in storage facility  102  to perform) various operations associated with integrating imagery captured by different imaging modalities into composite imagery of a surgical space. For example, processing facility  104  may be configured to generate composite imagery that includes integrated representations of a surgical space as captured by multiple different imaging modalities. For instance, processing facility  104  may be configured to generate a composite image that includes a representation of a first portion of the surgical space as captured by a first imaging modality and a representation of a second portion of the surgical space as captured by a second imaging modality. Processing facility  104  may be configured to integrate the representation of the second portion of the surgical space with the representation of the first portion of the surgical space such that the representations become an integrated whole within the composite image. Processing facility  104  may perform the integration in any of the ways described herein and in a manner that augments imagery of the surgical space as captured by one imaging modality (e.g., endoscopic imaging) with imagery of the surgical space as captured by a second imaging modality (e.g., ultrasound, CT, or MRI imaging). 
     These and other operations that may be performed by processing facility  104  are described herein. In the description that follows, any references to operations performed by system  100  may be understood to be performed by processing facility  104  of system  100 . 
       FIG. 2  illustrates a configuration  200  in which system  100  is configured to generate composite imagery of a surgical space based on imagery captured by different imaging modalities. As shown, configuration  200  may include multiple imaging modalities  202  (e.g., imaging modalities  202 - 1  and  202 - 2 ) configured to capture imagery  204  (e.g., imagery  204 - 1  captured by imaging modality  202 - 1  and imagery  204 - 2  captured by imaging modality  202 - 2 ) of a surgical space  206 . 
     Surgical space  206  may include any volumetric space associated with a surgical procedure. For example, surgical space  206  may include any part or parts of a body of a patient, such as anatomy  208  (e.g., tissue, etc.) of the patient in a space associated with the surgical procedure. Surgical space  206  may, in certain examples, be entirely disposed within the patient and may include a space within the patient near where a surgical procedure is planned to be performed, is being performed, or has been performed. For example, for a minimally invasive surgical procedure being performed on tissue internal to a patient, surgical space  206  may include the tissue, anatomy underlying the tissue, as well as space around the tissue where, for example, surgical instruments being used to perform the surgical procedure are located. In other examples, surgical space  206  may be at least partially disposed external to the patient. For instance, for an open surgical procedure being performed on a patient, part of surgical space  206  (e.g., tissue being operated on) may be internal to the patient while another part of surgical space  206  (e.g., a space around the tissue where one or more surgical instruments may be disposed) may be external to the patient. Surgical space  206  may include a real workspace in which a surgical procedure is performed, such as an actual, real-world workspace associated with a patient and in which one or more surgical instruments are used to perform the surgical procedure on the patient. 
     As used herein, a surgical procedure may include any medical procedure, including any diagnostic or treatment procedure in which manual and/or instrumental techniques are used on a patient to investigate or treat a physical condition of the patient. A surgical procedure may refer to any phases of a medical procedure, such as preoperative, operative (i.e., intraoperative), and postoperative phases of a surgical procedure. 
     Imaging modalities  202  may be configured and/or used to capture imagery  204  of surgical space  206 . Such a capture is represented by dashed lines  210  in  FIG. 2 . Imaging modalities  202  may each capture imagery  204  of surgical space  206  in any suitable manner and at any suitable time. Accordingly, one or more imaging modalities  202  may capture imagery  204  of surgical space  206  during one or more preoperative, intraoperative, and/or postoperative phases of a surgical procedure. 
     Imaging modalities  202  may include any set of different imaging modalities that may be used to capture imagery of a surgical space. Examples of imaging modalities  204  include, without limitation, endoscopic imaging by an endoscope, ultrasound imaging by an ultrasound machine, CT imaging by a CT machine, and MRI imaging by an MRI machine. Any suitable additional or alternative imaging modalities may be used in other examples. In certain implementations, imaging modality  202 - 1  may include endoscopic imaging by an endoscope, and imaging modality  202 - 2  may include any different imaging modality such as ultrasound imaging by an ultrasound machine, CT imaging by a CT machine, or MRI imaging by an MRI machine. In such implementations, imaging modality  202 - 1  may capture imagery  204 - 1  that is endoscopic imagery of surgical space  206 , and imaging modality  202 - 2  may capture imagery  204 - 2  that is ultrasound imagery, CT imagery, or MRI imagery of surgical space  206 . 
     In certain examples, imaging modality  202 - 1  may be configured to capture imagery of surface anatomy included in surgical space (e.g., an outer surface of tissue included in the surgical space), and imaging modality  202 - 2  may be configured to capture imagery of subsurface anatomy included in the surgical space (e.g., subsurface tissue that is behind the outer surface of tissue included in the surgical space). For example, imaging modality  202 - 1  may include endoscopic imaging by an endoscope that captures images of surface tissue within a patient, and imaging modality  202 - 1  may include ultrasound, CT, or MRI imaging that captures images of subsurface tissue that, from the perspective of the endoscope, is behind and hidden from the view of the endoscope by the surface tissue within the patient. 
     As mentioned, imaging modalities  202  may each capture imagery  204  of surgical scene  206  at any suitable time, such as during any phase(s) of a surgical procedure. In certain examples, imaging modalities  202  may concurrently capture imagery  204  of surgical space  206 . For instance, imaging modality  202 - 1  may capture endoscopic imagery during a surgical procedure (e.g., during an operative phase of the surgical procedure), and imaging modality  202 - 1  may concurrently capture another type of imagery during the surgical procedure. In other examples, imaging modalities  202  may capture imagery  204  of surgical space  206  at different times and/or during different phases of the surgical procedure. For instance, imaging modality  202 - 1  may capture endoscopic imagery during an operative phase of the surgical procedure, and imaging modality  202 - 2  may capture another type of imagery during a preoperative phase of the surgical procedure. 
     Imagery  204  of surgical space  206  may include images of surgical space  206  captured by imaging modalities  202 . For example, imagery  204  may include endoscopic images, ultrasound images, CT images, MRI images, and/or any other suitable form of images of surgical space  206 . Imagery  204  may include any suitable type of images represented by data in any suitable data format. For example, imagery  204  may include still-frame images, video, color images, infrared images, and/or any other type of images that may visually represent surgical space  206 . An image captured by an imaging modality may include a grid of pixels having values (e.g., color values, brightness values, etc.) representative of an appearance of surgical space  206  as captured by the imaging modality. Color values for pixels in a captured image may represent actual, organic colors of the surgical space as captured by an imaging modality. 
     Additionally or alternatively, imagery  204  may include one or more models of surgical space  206  that are generated based on imaging performed by an imaging modality. For example, imagery  204  may include a three-dimensional (3D) model of surgical space  206  that is generated based on imaging performed by an imaging modality, such as imaging performed by an ultrasound machine, a CT machine, an MRI machine, or other suitable imaging modality. The 3D model may be a full volumetric model that includes voxels (i.e., volumetric pixels) having values (e.g., color values, brightness values, etc.) representative of an appearance of surgical space  206  at 3D points within the model. Such a volumetric model may facilitate any slice of the 3D model being identified and used by system  100  to produce an image of the slice of the 3D model. Color values for pixels in the slice image may represent actual, organic colors of the surgical space as captured by an imaging modality. 
     While  FIG. 2  depicts two imaging modalities  202 - 1  and  202 - 2  respectively capturing imagery  204 - 1  and  204 - 2  that are provided as input to system  100 , other examples may include any suitable number and/or configuration of multiple, different imaging modalities that capture imagery that is provided as input to system  100  for use in generating composite imagery of surgical space  206 . For example, three or more different imaging modalities may capture imagery that is input to system  100  for use in generating composite imagery of surgical space  206 . 
     System  100  may generate composite imagery  212  of surgical space  206  based on imagery  204  captured by imaging modalities  202 . System  100  may do this in any of the ways described herein to generate a composite image that includes integrated representations of portions of surgical space  206  as captured by different imaging modalities  202 . Examples of such composite images and how the composite images may be generated are described herein. 
     System  100  may direct a display device  214  to display composite imagery  212 . For example, system  100  may provide data representative of composite imagery  212  to display device  214 , which may be configured to display composite imagery  212  for viewing by a user of a computer-assisted surgical system. Display device  214  may include any device capable of receiving and processing imagery data to display one or more images. To this end, display device  214  may include one or more display screens on which images may be displayed. In certain examples, display device  214  may be a component of or communicatively connected to a computer-assisted surgical system. 
       FIG. 3  illustrates an exemplary composite image  300  that may be generated by system  100  and displayed by a display device. Composite image  300  may be an image of a surgical space and may include a representation  302  of an augmentation region positioned relative to the surgical space. The positioning of augmentation region  302  within composite image  300  may represent and/or be determined from a position of augmentation region  302  (e.g., a position of a virtual object representing augmentation region  302 ) relative to the surgical space. Examples of positioning of augmentation region  302  relative to the surgical space are described herein. 
     Augmentation region  302  may be any suitable shape that defines an area within composite image  300 . For example, augmentation region  302  may be a circle, an oval, a quadrilateral (e.g., a rectangle, a fan), a triangle, or any other suitable shape. 
     The positioning of augmentation region  302  within composite image  300  may define two portions of composite image  300 —a first portion that is outside augmentation region  302 , and a second portion that is inside augmentation region  302 . In the first portion of composite image  300 , which is outside augmentation region  302 , composite image  300  may include a representation  304  of the first portion of the surgical space as captured by a first imaging modality. For example, representation  304  may include imagery of the surgical space captured by the first imaging modality, such as imagery  204 - 1  captured by first imaging modality  202 - 1 . In the second portion of composite image  300 , which is inside augmentation region  302 , composite image  300  may include a representation  306  of the second portion of the surgical space as captured by a second imaging modality. For example, representation  306  may include imagery of the surgical space captured by the second imaging modality and modified by a feature of imagery of the surgical space captured by the first imaging modality, such as imagery  204 - 2  captured by second imaging modality  202 - 2  and modified by a feature of imagery  204 - 1  captured by first imaging modality  202 - 1 . Accordingly, representation  306  of the second portion of the surgical space may be generated based on both imagery  204 - 1  and imagery  204 - 2  and may include a composition of imagery  204 - 2  and a feature (e.g., gradient information) of imagery  204 - 1 . As indicated herein, this composition may create a visually realistic appearance of depth of representation  306  when representation  306  is integrated with representation  304  in composite image  300 . In  FIG. 3 , representation  304  is illustrated to include diagonal lines, and representation  306  is illustrated to include vertical lines to indicate that representations  304  and  306  represent the surgical space as captured by different imaging modalities. 
     In composite image  300 , representation  304  of the first portion of the surgical space as captured by the first imaging modality is augmented with integrated representation  306  of the second portion of the surgical space as captured by the second imaging modality. Accordingly, a surgeon and/or other surgical team member viewing composite image  300  may concurrently visualize integrated representations  304  and  306  of portions of the surgical space as captured by different imaging modalities. Because representation  306  is positionally integrated within representation  304 , the surgeon may visualize the surgical space as captured by the different imaging modalities without having to mentally align the representations  304  and  306  to one another and the surgical space as would be required if representations  304  and  306  were presented separately and were not positionally integrated with one another. 
     In certain examples, augmentation region  302  may be movable relative to the surgical space by way of user input to a computer-assisted surgical system. The computer-assisted surgical system may be configured to receive any suitable user input that may be used to move augmentation region  302  relative to the surgical space. Such input may include actuation of buttons, movement of a controller (e.g., a joystick controller, a master control, etc.), movement of a surgical instrument connected to the computer-assisted surgical system (e.g., movement of an ultrasound probe or other surgical instrument from which augmentation region  302  is projected), and/or any other suitable user input. 
     Such movement of augmentation region  302  may allow a user of the computer-assisted surgical system to select, on the fly during a surgical procedure, a particular portion of the surgical space that is to be viewed as captured by the second imaging modality instead of as captured by the first imaging modality. This may allow a surgeon to dynamically “spotlight” a select portion of the surgical space in order to view the select portion as captured by the second imaging modality. For example, representation  304  may represent surface anatomy of a patient as captured by an endoscope, and representation  306  may represent subsurface anatomy of the patient as captured by a different imaging modality such as an ultrasound, CT, or MRI device. In this example, the surgeon may position augmentation region  302  to view subsurface anatomy at a select portion of the surgical space, while still viewing surface anatomy at another portion of the surgical space. In such implementations, augmentation region  302  may function as a virtual cut-away region (e.g., a virtual cut plane) that may be used by a surgeon to select a portion of a representation of surface anatomy to be virtually cut away from view to reveal a representation of subsurface anatomy located behind the surface anatomy (e.g., a virtual cut plane into a preoperative 3D model of the surgical space that is registered with an endoscopic view of the surgical space). 
     Movement of augmentation region  302  relative to the surgical space may include movement in any suitable direction(s) relative to the surgical space. For example, the movement may include lateral movement that pans augmentation region  302  across an image of the surgical space. Additionally or alternatively, the movement may include depth movement that changes a distance of augmentation region  302  from the perspective viewpoint from which the image of the surgical space is rendered. Such depth movement of augmentation region  302  may position augmentation region  302  at different depths relative to the surgical space, which position may be used to identify a slice of a virtual representation of the surgical space to be rendered (e.g., a slice of a 3D model that is mapped to a virtual representation of the surgical space). Such freedom of movement of augmentation region  302  may provide a user of the computer-assisted surgical system flexibility to select, on the fly during a surgical procedure, a particular portion of the surgical space to be augmented and imagery to be used for the augmentation. 
     To generate a composite image of a surgical space, system  100  may determine an image render viewpoint from which to render an image of the surgical space and, from a perspective of the image render viewpoint, a position of an augmentation region relative to the surgical space. System  100  may generate a composite image of the surgical space from the perspective of the image render viewpoint and based on the determined position of the augmentation region relative to the surgical space. The composite image may include: the augmentation region at the determined position of the augmentation region relative to the surgical space; outside the augmentation region, a representation of a first portion of the surgical space as captured by a first imaging modality; and inside the augmentation region, a representation of a second portion of the surgical space as captured by a second imaging modality. The representation of the second portion of the surgical space may be generated in any of the ways described herein and may be based on first imagery of the surgical space captured by the first imaging modality and second imagery of the surgical space captured by the second imaging modality. 
       FIG. 4  illustrates an exemplary depiction of a surgical space  400  with an image render viewpoint  402  and augmentation region  404  positioned relative to surgical space  400 . While the depiction shows a two-dimensional (2D) view, principles described with respect to the 2D view also apply to a 3D view of a surgical space with an image render viewpoint  402  and an augmentation region  404  positioned relative to the surgical space. 
     As shown in  FIG. 4 , surgical space  400  includes an anatomical structure  406 , which includes surface anatomy  408  and subsurface anatomy  410 . Subsurface anatomy  410  may include any anatomy positioned behind surface anatomy  408  from the perspective of image render viewpoint  402  and/or hidden from view from the perspective of image render viewpoint  402  by surface anatomy  408 . In certain examples, surface anatomy  408  may include an outer layer of tissue of a patient, and subsurface anatomy  410  may include anatomy embedded within the outer layer of tissue. 
     Image render viewpoint  402  (“viewpoint  402 ”) may be any viewpoint from which an image of surgical space  400  may be rendered. Viewpoint  402  may include an actual viewpoint of an imaging modality such as an endoscope (e.g., a viewpoint of one or more cameras of an endoscope). Alternatively, viewpoint  402  may include a virtual viewpoint corresponding to an actual viewpoint of an imaging modality such as an endoscope. Viewpoint  402  may be associated with and/or represent intrinsic and extrinsic properties of an imaging device such as one or more cameras of an endoscope. Viewpoint  402  may have a field of view within which an image of surgical space  400  may be rendered. A space within solid-line arrows  412  extending from viewpoint  400  represents a field of view of viewpoint  402 . 
     As shown, viewpoint  402  is located at a position relative to surgical space  400  and defines a perspective from which an image of surgical space  400  may be rendered. The position of viewpoint  402  illustrated in  FIG. 4  is exemplary only. Viewpoint  402  may be located at any position relative to surgical space  400  from which an image of surgical space  400  may be rendered. 
     Augmentation region  404  may be positioned relative to surgical space  400  to define a portion of surgical space  400  that is to be augmented. Augmentation region  404  may be defined to include any suitable shape, area, or volume that may be positioned relative to surgical space  400  to delineate, from the perspective of viewpoint  402 , a portion of surgical space  400  that is to be augmented. In  FIG. 4 , augmentation region  404  is represented as a side view of a planar shape, which may be a circle, oval, quadrilateral, or any other suitable planar shape. 
     In certain examples, augmentation region  404  may be a virtual object or a view of a virtual object from the perspective of viewpoint  402 . For example, a virtual object may be defined and positioned relative to surgical space. The virtual object may be a 2D or 3D object. The virtual object may be movable relative to surgical space  400  by way of user input to a computer-assisted surgical system. 
     At a given point in time, system  100  may determine positions of viewpoint  402  and augmentation region  404  relative to surgical space  400  and generated a composite image of surgical space  400  based on the determined positions of viewpoint  402  and augmentation region  404  relative to surgical space  400 . In the composite image, a first portion of surgical space  400  may be represented with imagery as captured by a first imaging modality, and a second portion of surgical space  400  may be represented with imagery as captured by a second imaging modality. 
     To this end, system  100  may use the determined positions of viewpoint  402  and augmentation region  404  relative to surgical space  400  to define the first and second portions of surgical space  400 . To illustrate,  FIG. 4  shows dashed lines extending from viewpoint  402  and intersecting boundaries of augmentation region  404  to define alignment boundaries  414 . 
     Portions of surgical space  400  that are outside of a space within alignment boundaries  414  are referred to as unaligned portions  416  of surgical space  400  because these portions are not aligned with augmentation region  404  from the perspective of viewpoint  402 . Unaligned portions  416  of surgical space  400  may make up a first portion of surgical space  400  in a composite image of surgical space  400 . 
     A portion of surgical space  400  that is inside a space within alignment boundaries  414  is referred to as an aligned portion  418  of surgical space  400  because this portion is aligned with augmentation region  404  from the perspective of viewpoint  402 . Aligned portion  418  of surgical space  400  may make up a second portion of surgical space  400  in the composite image of surgical space  400 . 
     In the composite image of surgical space  400 , a representation of the first portion of surgical space  400  (a representation of unaligned portions  416  of surgical space  400 ) may be generated based on imagery captured by a first imaging modality. For example, the first imaging modality may include an endoscope positioned at viewpoint  402  to capture endoscopic imagery of surgical space  400 , and the representation of the first portion of surgical space  400  may include endoscopic imagery of surface anatomy  408  in the unaligned portions  416  of surgical space  400 . 
     In the composite image of surgical space  400 , a representation of the second portion of surgical space  400  (a representation of aligned portion  418  of surgical space  400 ) may be generated based on imagery captured by a second imaging modality that is different from the first imaging modality. For example, the second imaging modality may include an ultrasound, CT, or MRI device that captured ultrasound, CT, or MRI imagery of surgical space  400 , and the representation of the second portion of surgical space  400  may include ultrasound, CT, or MRI imagery of surface anatomy  408  or subsurface anatomy  410  in the aligned portion  418  of surgical space  400 . In examples in which the representation of the second portion of surgical space  400  is generated based on imagery of subsurface anatomy  410  in the aligned portion  418  of surgical space  400 , the imagery may be of subsurface anatomy  410  and any depth or depths behind the surface anatomy  408 . In some implementations, a depth of imagery of the subsurface anatomy  410  as captured by the second imaging modality may be selected (e.g., on the fly during a surgical procedure) by user input to a computer-assisted surgical system, such as by user input that moves augmentation region  404  in a manner that changes the distance between viewpoint  402  and augmentation region  404  and/or moves augmentation region  404  to a select depth within subsurface anatomy  410 . 
     As described herein, the representation of the second portion of surgical space  400  in the composite image may be generated based on imagery captured by the second imaging modality and imagery captured by the first imaging modality. For example, the representation of the second portion of surgical space  400  may include a composition of imagery of subsurface anatomy  410  within aligned region  418  as captured by the second imaging modality and a feature of imagery of surface anatomy  408  within aligned region  418  as captured by the first imaging modality. For instance, system  100  may extract gradient information from the imagery of surface anatomy  408  within aligned region  418  and generate slope imagery representing the extracted gradient information. System  100  may modify the imagery of subsurface anatomy  410  within aligned region  418  as captured by the second imaging modality with the slope imagery, such as by summing the extracted slope imagery and the imagery of subsurface anatomy  410  within aligned region  418  as captured by the second imaging modality to generate a composition for the representation of the second portion of surgical space  400  in the composite image. As described, the composition may provide a visually realistic representation of depth of subsurface anatomy  410  relative to surface anatomy  408  in the composite image. 
     In certain examples, the combining of the slope imagery extracted from imagery of surface anatomy  408  with the imagery of subsurface anatomy  410  may be performed using actual, organic color values of the imagery of surface anatomy  408  and/or subsurface anatomy  410 , without using artificial or non-photorealistic colors. This may contribute to the visually realistic representation of the surgical space, including the visually realistic representation of depth of subsurface anatomy  410  relative to surface anatomy  408  in the composite image. 
     An exemplary way of generating a composite image of a surgical space will now be described.  FIG. 5A  illustrates a real workspace  502  that may be included in a surgical space. The real workspace  502  may be a real-world physical workspace located in front of an endoscope  504  configured to capture endoscopic imagery of the workspace. In certain examples, the real workspace  502  may include anatomy  506  of a patient and one or more surgical instruments  508  (e.g., surgical instruments  508 - 1  and  508 - 2 ) positioned relative to anatomy  506  in the real workspace  502 . In the illustrated example, surgical instrument  508 - 1  is a grasper tool, and surgical instrument  508 - 2  is an ultrasound probe. 
     System  100  may access a real image of the real workspace  502 . For example, system  100  may access a real image of the real workspace  502  as captured by endoscope  504 .  FIG. 5B  illustrates an example of a real image (R) of the real workspace  502  as captured by endoscope  504 . 
     System  100  may generate a slope image from real image (R). For example, system  100  may extract gradient information from real image (R) and use the extracted gradient information to generate a slope image that represents the gradient information extracted from real image (R). The gradient information may represent directional change in a feature of real image (R), such as a directional change in intensity, color, or another feature of real image (R). The gradient information may represent change in one or more directions. 
       FIG. 5C  illustrates an example of a slope image (S) extracted from real image (R). Slope image (S) is illustrated in black and white in  FIG. 5C . However, slope image (S) may include black, white, and/or gray in various shades that represent degrees of slope. Slope image (S) may represent any suitable gradient information, including horizontal gradient, vertical gradient, one or more other directional gradients, or any combination or sub-combination thereof. 
     System  100  may generate and maintain a virtual workspace representative of the real workspace  502 . The virtual workspace may be a 3D space (e.g., a 3D coordinate space) to which imagery of the real workspace  502  as captured by different imaging modalities may be mapped. For example, endoscopic imagery captured by endoscope  504  and other imagery captured by one or more other imaging modalities may be mapped to the virtual workspace such that the endoscopic imagery and the other imagery are registered to one another in the virtual workspace. 
     The registration may be performed in any suitable way. For example, depth values may be determined and associated with pixels in real image (R) to generate a 3D mesh of 3D coordinate points that are associated with color values of the pixels. The 3D mesh may be mapped to the virtual workspace. 
     In examples in which other imagery captured by another imaging modality includes a 3D model of a surgical space, system  100  may map the 3D model to the virtual workspace. This may be performed in any suitable way and may include system  100  registering features in the 3D model to matching features of the 3D mesh generated from endoscopic imagery and depth information associated with the endoscopic imagery. Accordingly, the 3D model may be registered to the 3D mesh in the virtual workspace. 
     In examples in which other imagery captured by another imaging modality includes a 2D image of a surgical space and depth data for the 2D image is available, system  100  may map the 2D image to the virtual workspace similarly to how system  100  maps endoscopic imagery to the virtual workspace. In examples in which other imagery captured by another imaging modality includes a 2D image of a surgical space but depth data for the 2D image is unavailable, system  100  may project the 2D image to any suitable surface in the virtual workspace, such as the surface of a virtual object representing an augmentation region in the virtual workspace. 
       FIG. 6A  illustrates an exemplary virtual workspace  602  that may be generated by system  100  based on and/or representative of the real workspace  502 . The virtual workspace  602  may include virtual representations of elements of the real workspace  502 , such as a virtual representation  606  of anatomy  506  and virtual representations  608  (e.g., virtual representations  608 - 1  and  608 - 2 ) of surgical instruments  508  (e.g., surgical instruments  508 - 1  and  508 - 2 ). System  100  may generate the virtual representations in the virtual workspace in any suitable way, including based on real image (R) of the real workspace  502  and depth information associated with real image (R). 
     The virtual workspace  602  may also include an image render viewpoint  604  (“viewpoint  604 ”), which may be a virtual viewpoint corresponding to the viewpoint of endoscope  504  included in the real workspace  502 . Viewpoint  604  may be configured based on intrinsic and extrinsic properties of endoscope  504 . Viewpoint  604  may be positioned relative to other elements of the virtual workspace  602  and may represent a viewpoint perspective from which an image of the virtual workspace  602  may be rendered. 
     The virtual workspace  602  may also include an augmentation region  610  positioned relative to other elements of the virtual workspace  602 . In the example illustrated in  FIG. 6A , the position of augmentation region  610  is determined based on ultrasound probe  608 - 2  by projecting augmentation region  610  from ultrasound probe  608 - 2  in a particular manner (e.g., in a particular direction, orientation, pose, shape, etc.) such that augmentation region  610  is positioned relative to ultrasound probe  608 - 2 , viewpoint  604 , and other elements of the virtual workspace  602 . 
     System  100  may project imagery captured by ultrasound probe  608 - 2  onto augmentation region  610  in the virtual workspace  602 . The ultrasound imagery projected onto augmentation region  610  is represented by horizontal-line fill pattern  612  in  FIG. 6A . While the example illustrated in  FIG. 6A  depicts a projection of ultrasound imagery onto augmentation region  610 , any other imagery captured by another imaging modality may be projected onto augmentation region  610  in the virtual workspace  602 . For example, system  100  may determine a slice of a 3D model (e.g., a 3D model generated from CT or MRI imagery) based on a position of augmentation region  610  relative to the 3D model registered to the virtual workspace  602  and project an image of the slice onto augmentation region  610 . In such an example, augmentation region  610  projected from ultrasound probe  608 - 2  may function as a placeholder onto which an image of a slice of a registered 3D model of the surgical space  602  may be projected in the virtual workspace  602 . 
     In certain examples, an image that is projected onto augmentation region  610  in the virtual workspace may be selected by way of user input to a computer-assisted surgical system. For example, a user of the computer-assisted surgical system may provide input to toggle from one imaging modality image being projected onto augmentation region  610  to another imaging modality image being projected onto augmentation region  610  (e.g., from an ultrasound image to a CT or MRI model image or vice versa). 
     System  100  may be configured to use the virtual workspace  602  in any suitable way to generate a composite image of the surgical space. For example, system  100  may generate an image of the virtual workspace  602  from the perspective of viewpoint  604 .  FIG. 6B  illustrates an example of an image (V), which may be referred to as a virtual image (V), of the virtual workspace  602  rendered by system  100  from the perspective of viewpoint  604 . As described herein, system  100  may be configured to use virtual image (V) to generate a composite image of the surgical space. 
     System  100  may generate a mask image such as a binary render mask image based on the virtual workspace  602  and/or virtual image (V). The mask image may correspond in size to virtual image (V) and may include a first portion that is aligned with the position of augmentation region  610  (e.g., an area inside of augmentation region  610 ) and that is assigned a first binary value, and a second portion that is not aligned with the position of augmentation region  610  (e.g., an area outside of augmentation region  610 ) and that is assigned a second binary value different from the first binary value.  FIG. 6C  illustrates an example of a mask image (M) that may be generated by system  100  based on virtual image (V). As shown, mask image (M) includes a first portion  622  including a white fill representing one binary value, and a second portion  624  including a black fill representing another binary value. 
     System  100  may be configured to use real image (R), slope image (S), virtual image (V), and mask image (M) to generate a composite image (C) of the surgical space. For example, system  100  may perform a blend function that generates a composite image (C) based on the real image (R), slope image (S), virtual image (V), and mask image (M). In certain implementations, the following blend function may be performed by system  100  for i, j iterating over the image width and height, respectively: 
         C =blend( R,S,V,M )= M   (i,j) *( S   (i,j)   +V   (i,j) )+(1−M (i,j) )* R   (i,j)  
 
     In this blend function, mask image (M) may have a binary value of “1” in a first portion that is aligned with augmentation region  610  and a binary value of “0” in a second portion that is not aligned with augmentation region  610 . Accordingly, system  100  may use real image (R) for all pixel locations that are set to “0” in mask image (M) and may use a blended output of virtual image (V) and slope image (S) for all pixel locations that are set to “1” in mask image (M). 
     Based on this blend function, the first portion of the composite image (C) may include a representation of the surgical scene as captured by endoscope  504 , and the second portion of the composite image (C) may include a representation of the surgical scene as captured by another imaging modality. The representation of the second portion of the surgical scene as captured by another imaging modality may include a composition of imagery of the surgical space as captured by the other imaging modality and a feature of the endoscopic imagery of the surgical space. For instance, to produce the representation of the second portion of the surgical space, system  100  may combine the imagery of the second portion of the surgical space as captured by the other imaging modality (e.g., this may include the imagery as mapped to the augmentation region  610  in the virtual workspace  602  and/or as represented in virtual image (V)) and slope imagery representing gradient information extracted from the endoscopic imagery of the second portion of the surgical space. This combination may be performed by system  100  executing the blend function iterating over the pixel locations of the composite image (C) and selectively using values at corresponding pixel locations in real image (R), slope image (S), virtual image (V), and mask image (M), as indicated by the blend function, to generate the composite image (C). In certain examples, this may be performed without using artificial colors to generate composite image (C). 
       FIG. 7  illustrates an example of a composite image (C) that may be generated by system  100  performing a blend function to generate composite image (C) based on the real image (R), slope image (S), virtual image (V), and mask image (M). As shown, composite image (C) may include a representation  702  of augmentation region  610 . Outside the representation  702  of augmentation region  610 , composite image (C) includes a representation  704  of a first portion of the surgical space, which representation includes endoscopic imagery of surface anatomy as captured by endoscope  504 . Inside the representation  702  of augmentation region  610 , composite image (C) includes a representation  706  of a second portion of the surgical space as captured by another imaging modality (e.g., an ultrasound probe), which representation includes a composition of imagery captured by the other imaging modality and a feature of the endoscopic imagery (e.g., a slope of the endoscopic imagery) of the second region of the surgical space. 
     A composite image, such as composite image (C), may include any suitable representation of an augmentation region. Such a representation may include any visual representation of a boundary or transition between representations of first and second portions of a surgical scene in the composite image. 
     While  FIG. 5A - FIG. 7  illustrate an example in which a first imaging modality includes an endoscope and a second imaging modality includes an ultrasound probe, images as captured by other different imaging modalities may be similarly processed to generate a composite image of a surgical space. In other examples, for instance, a first imaging modality may include an endoscope, and a second imaging modality may include a CT or MRI machine. In such examples, images may be captured by the CT or MRI machine during a preoperative phase of a surgical procedure and processed to generate a 3D model of the surgical space. System  100  may register the 3D model of the surgical space to the endoscopic imagery of the surgical space in a virtual workspace. System  100  may determine a position of an image render viewpoint relative to the surgical space, determine a position of an augmentation region relative to the surgical space, and use the position of the image render viewpoint and the position of the augmentation region relative to the surgical space to identify an image of the 3D model (e.g., a planar slice of the 3D image) to be used to generate a representation of the surgical space within the augmentation region. For example, system  100  may project the identified image of the 3D model onto the augmentation region in the virtual workspace and perform a blend function as described herein to generate a composite image of the surgical space. 
     In certain implementations, for example, system  100  may project an augmentation region from an ultrasound probe positioned in the surgical space. To this end, system  100  may access tracking information (e.g., position information, orientation information, movement information, kinematic information, etc.) for the ultrasound probe from a computer-assisted surgical system to which the ultrasound probe is connected and use the tracking information to identify a pose of the ultrasound probe (e.g., a position and an orientation of the ultrasound probe) within the surgical space. System  100  may project the augmentation region into the surgical space (e.g., into a virtual workspace representing a real workspace within the surgical space) based on the pose of the ultrasound probe. 
     In certain examples, system  100  may generate a composite image of the surgical space that includes, within the augmentation region, a representation of ultrasound imagery of the surgical space as captured by the ultrasound probe. In other examples, system  100  may generate a composite image of the surgical space that includes, within the augmentation region, a representation of a portion of the surgical space as captured by a different imaging modality. For example, the representation within the augmentation region may include or may be based on CT or MRI imagery of the surgical space (e.g., a 3D model of the surgical space generated from CT or MRI imaging of the surgical space). In such an example, the augmentation region projected from the ultrasound probe may function as a virtual cut-away region and/or a placeholder on which to project the CT-based or MRI-based representation of the surgical space. Accordingly, a user of a computer-assisted surgical system may provide input to position the ultrasound probe within the surgical space to select a position of the augmentation region to define a portion of the surgical space to be augmented with an image of a registered 3D model of the surgical space. As mentioned, in certain examples, system  100  may be configured to toggle the representation within the augmentation region between representing the ultrasound imagery as captured by the ultrasound probe and representing other imagery as captured by another imaging modality (e.g., CT or MRI imagery captured by a CT or MRI machine). 
     Use of an ultrasound probe to define and move an augmentation region relative to the surgical space is illustrative of certain examples. Other examples may implement a different real-world surgical instrument, a virtual object, or any other suitable mechanism to be used by a user to define and move an augmentation region relative to the surgical space. 
     As mentioned, system  100  may be implemented in or communicatively coupled to a computer-assisted surgical system. System  100  may receive input from and provide output to the computer-assisted surgical system. For example, system  100  may access imagery of a surgical space and/or any information about the surgical space and/or the computer-assisted surgical system from the computer-assisted surgical system, use the accessed imagery and/or information to perform any of the processing described herein to generate composite imagery of the surgical space, and provide data representative of the composite imagery to the computer-assisted surgical system for display (e.g., by a display device associated with the computer-assisted surgical system). 
       FIG. 8  illustrates an exemplary computer-assisted surgical system  800  (“surgical system  800 ”). System  100  may be implemented by surgical system  800 , connected to surgical system  800 , and/or otherwise used in conjunction with surgical system  800 . 
     As shown, surgical system  800  may include a manipulating system  802 , a user control system  804 , and an auxiliary system  806  communicatively coupled one to another. Surgical system  800  may be utilized by a surgical team to perform a computer-assisted surgical procedure on a patient  808 . As shown, the surgical team may include a surgeon  810 - 1 , an assistant  810 - 2 , a nurse  810 - 3 , and an anesthesiologist  810 - 4 , all of whom may be collectively referred to as “surgical team members  810 .” Additional or alternative surgical team members may be present during a surgical session as may serve a particular implementation. 
     While  FIG. 8  illustrates an ongoing minimally invasive surgical procedure, it will be understood that surgical system  800  may similarly be used to perform open surgical procedures or other types of surgical procedures that may similarly benefit from the accuracy and convenience of surgical system  800 . Additionally, it will be understood that the surgical session throughout which surgical system  800  may be employed may not only include an operative phase of a surgical procedure, as is illustrated in  FIG. 8 , but may also include preoperative, postoperative, and/or other suitable phases of the surgical procedure. 
     As shown in  FIG. 8 , manipulating system  802  may include a plurality of manipulator arms  812  (e.g., manipulator arms  812 - 1  through  812 - 4 ) to which a plurality of surgical instruments may be coupled. Each surgical instrument may be implemented by any suitable surgical tool (e.g., a tool having tissue-interaction functions), medical tool, imaging device (e.g., an endoscope, an ultrasound tool, etc.), sensing instrument (e.g., a force-sensing surgical instrument), diagnostic instrument, or the like that may be used for a computer-assisted surgical procedure on patient  808  (e.g., by being at least partially inserted into patient  808  and manipulated to perform a computer-assisted surgical procedure on patient  808 ). While manipulating system  802  is depicted and described herein as including four manipulator arms  812 , it will be recognized that manipulating system  802  may include only a single manipulator arm  812  or any other number of manipulator arms as may serve a particular implementation. 
     Manipulator arms  812  and/or surgical instruments attached to manipulator arms  812  may include one or more displacement transducers, orientational sensors, and/or positional sensors used to generate raw (i.e., uncorrected) kinematics information. One or more components of surgical system  800  may be configured to use the kinematics information to track (e.g., determine positions of) and/or control the surgical instruments. 
     User control system  804  may be configured to facilitate control by surgeon  810 - 1  of manipulator arms  812  and surgical instruments attached to manipulator arms  812 . For example, surgeon  810 - 1  may interact with user control system  804  to remotely move or manipulate manipulator arms  812  and the surgical instruments. To this end, user control system  804  may provide surgeon  810 - 1  with imagery (e.g., high-definition 3D imagery) of a surgical space associated with patient  808  as captured by an imaging system (e.g., any of the medical imaging systems described herein). In certain examples, user control system  804  may include a stereo viewer having two displays where stereoscopic images of a surgical space associated with patient  808  and generated by a stereoscopic imaging system may be viewed by surgeon  810 - 1 . In certain examples, composite imagery generated by system  100  may be displayed by user control system  804 . Surgeon  810 - 1  may utilize the imagery displayed by user control system  804  to perform one or more procedures with one or more surgical instruments attached to manipulator arms  812 . 
     To facilitate control of surgical instruments, user control system  804  may include a set of master controls. These master controls may be manipulated by surgeon  810 - 1  to control movement of surgical instruments (e.g., by utilizing robotic and/or teleoperation technology). The master controls may be configured to detect a wide variety of hand, wrist, and finger movements by surgeon  810 - 1 . In this manner, surgeon  810 - 1  may intuitively perform a procedure using one or more surgical instruments. 
     Auxiliary system  806  may include one or more computing devices configured to perform primary processing operations of surgical system  800 . In such configurations, the one or more computing devices included in auxiliary system  806  may control and/or coordinate operations performed by various other components (e.g., manipulating system  802  and user control system  804 ) of surgical system  800 . For example, a computing device included in user control system  804  may transmit instructions to manipulating system  802  by way of the one or more computing devices included in auxiliary system  806 . As another example, auxiliary system  806  may receive, from manipulating system  802 , and process image data representative of imagery captured by an imaging device attached to one of manipulator arms  812 . 
     In some examples, auxiliary system  806  may be configured to present visual content to surgical team members  810  who may not have access to the images provided to surgeon  810 - 1  at user control system  804 . To this end, auxiliary system  806  may include a display monitor  814  configured to display one or more user interfaces, such as images (e.g., 2D images) of the surgical space, information associated with patient  808  and/or the surgical procedure, and/or any other visual content as may serve a particular implementation. For example, display monitor  814  may display images of the surgical space (e.g., composite images generated by system  100 ) together with additional content (e.g., graphical content, contextual information, etc.) concurrently displayed with the images. In some embodiments, display monitor  814  is implemented by a touchscreen display with which surgical team members  810  may interact (e.g., by way of touch gestures) to provide user input to surgical system  800 . 
     Manipulating system  802 , user control system  804 , and auxiliary system  806  may be communicatively coupled one to another in any suitable manner. For example, as shown in  FIG. 8 , manipulating system  802 , user control system  804 , and auxiliary system  806  may be communicatively coupled by way of control lines  816 , which may represent any wired or wireless communication link as may serve a particular implementation. To this end, manipulating system  802 , user control system  804 , and auxiliary system  806  may each include one or more wired or wireless communication interfaces, such as one or more local area network interfaces, Wi-Fi network interfaces, cellular interfaces, etc. 
       FIG. 9  shows an exemplary method  900 . While  FIG. 9  illustrates exemplary operations according to one embodiment, other embodiments may omit, add to, reorder, combine, and/or modify any of the steps shown in  FIG. 9  One or more of the operations shown in in  FIG. 9  may be performed by a computing system such as system  100 , any components included therein, and/or any implementation thereof. 
     In operation  902 , a computing system determines an image render viewpoint from which to render an image of a surgical space. Operation  902  may be performed in any of the ways described herein. 
     In operation  904 , the computing system determines, from a perspective of the image render viewpoint, a position of an augmentation region relative to the surgical space. Operation  904  may be performed in any of the ways described herein. 
     In operation  906 , the computing system generates a composite image of the surgical space from the perspective of the image render viewpoint and based on the determined position of the augmentation region relative to the surgical space. Operation  906  may be performed in any of the ways described herein. 
     In operation  908 , the computing system directs a display device to display the composite image. Operation  908  may be performed in any of the ways described herein. 
     The composite image generated in operation  806  may be generated in any suitable way, including in any of the ways described herein. The composite image may include any of the exemplary elements described herein. For example, the composite image may include the augmentation region at the determined position of the augmentation region relative to the surgical space. Outside the augmentation region, the composite image may include a representation of a first portion of the surgical space as captured by a first imaging modality. Inside the augmentation region, the composite image may include a representation of a second portion of the surgical space as captured by a second imaging modality. 
     As described herein, the representation of a first portion of the surgical space as captured by a first imaging modality may include and/or may be generated based on the first imagery of the surgical space captured by the first imaging modality (e.g., an endoscope), and the representation of the second portion of the surgical space may be generated based on the first imagery of the surgical space captured by the first imaging modality and the second imagery of the surgical space captured by the second imaging modality (e.g., an ultrasound probe, a CT device, or an MRI device). For example, as described herein, the representation of the second portion of the surgical space may include a composition of the second imagery of the surgical space captured by the second imaging modality and a feature of the first imagery of the surgical space captured by the first imaging modality. 
     In some examples, a non-transitory computer-readable medium storing computer-readable instructions may be provided in accordance with the principles described herein. The instructions, when executed by a processor of a computing device, may direct the processor and/or computing device to perform one or more operations, including one or more of the operations described herein. Such instructions may be stored and/or transmitted using any of a variety of known computer-readable media. 
     A non-transitory computer-readable medium as referred to herein may include any non-transitory storage medium that participates in providing data (e.g., instructions) that may be read and/or executed by a computing device (e.g., by a processor of a computing device). For example, a non-transitory computer-readable medium may include, but is not limited to, any combination of non-volatile storage media and/or volatile storage media. Exemplary non-volatile storage media include, but are not limited to, read-only memory, flash memory, a solid-state drive, a magnetic storage device (e.g. a hard disk, a floppy disk, magnetic tape, etc.), ferroelectric random-access memory (“RAM”), and an optical disc (e.g., a compact disc, a digital video disc, a Blu-ray disc, etc.). Exemplary volatile storage media include, but are not limited to, RAM (e.g., dynamic RAM). 
       FIG. 10  illustrates an exemplary computing device  1000  that may be specifically configured to perform one or more of the processes described herein. Any of the systems, units, computing devices, and/or other components described herein may be implemented by computing device  1000 . 
     As shown in  FIG. 10 , computing device  1000  may include a communication interface  1002 , a processor  1004 , a storage device  1006 , and an input/output (“I/O”) module  1008  communicatively connected one to another via a communication infrastructure  1010 . While an exemplary computing device  1000  is shown in  FIG. 10 , the components illustrated in  FIG. 10  are not intended to be limiting. Additional or alternative components may be used in other embodiments. Components of computing device  1000  shown in  FIG. 10  will now be described in additional detail. 
     Communication interface  1002  may be configured to communicate with one or more computing devices. Examples of communication interface  1002  include, without limitation, a wired network interface (such as a network interface card), a wireless network interface (such as a wireless network interface card), a modem, an audio/video connection, and any other suitable interface. 
     Processor  1004  generally represents any type or form of processing unit capable of processing data and/or interpreting, executing, and/or directing execution of one or more of the instructions, processes, and/or operations described herein. Processor  1004  may perform operations by executing computer-executable instructions  1012  (e.g., an application, software, code, and/or other executable data instance) stored in storage device  1006 . 
     Storage device  1006  may include one or more data storage media, devices, or configurations and may employ any type, form, and combination of data storage media and/or device. For example, storage device  1006  may include, but is not limited to, any combination of the non-volatile media and/or volatile media described herein. Electronic data, including data described herein, may be temporarily and/or permanently stored in storage device  1006 . For example, data representative of computer-executable instructions  1012  configured to direct processor  1004  to perform any of the operations described herein may be stored within storage device  1006 . In some examples, data may be arranged in one or more databases residing within storage device  1006 . 
     I/O module  1008  may include one or more I/O modules configured to receive user input and provide user output. I/O module  1008  may include any hardware, firmware, software, or combination thereof supportive of input and output capabilities. For example, I/O module  1008  may include hardware and/or software for capturing user input, including, but not limited to, a keyboard or keypad, a touchscreen component (e.g., touchscreen display), a receiver (e.g., an RF or infrared receiver), motion sensors, and/or one or more input buttons. 
     I/O module  1008  may include one or more devices for presenting output to a user, including, but not limited to, a graphics engine, a display (e.g., a display screen), one or more output drivers (e.g., display drivers), one or more audio speakers, and one or more audio drivers. In certain embodiments, I/O module  1008  is configured to provide graphical data to a display for presentation to a user. The graphical data may be representative of one or more graphical user interfaces and/or any other graphical content as may serve a particular implementation. 
     In the preceding description, various exemplary embodiments have been described with reference to the accompanying drawings. It will, however, be evident that various modifications and changes may be made thereto, and additional embodiments may be implemented, without departing from the scope of the invention as set forth in the claims that follow. For example, certain features of one embodiment described herein may be combined with or substituted for features of another embodiment described herein. The description and drawings are accordingly to be regarded in an illustrative rather than a restrictive sense.