Patent Publication Number: US-9430093-B2

Title: Monitoring interactions between two or more objects within an environment

Description:
RELATED APPLICATION 
     This application is a continuation of U.S. application Ser. No. 13/109,598, filed on May 17, 2011, entitled “MONITORING INTERACTIONS BETWEEN TWO OR MORE OBJECTS WITHIN AN ENVIRONMENT”, at least some of which may be incorporated herein. 
    
    
     BACKGROUND 
     Today, mobile devices are becoming increasingly connected, powerful, and versatile. Mobile devices are able to perform many tasks that previously required a personal computer for operation. Some features of mobile devices may comprise internet connectivity, email, video chat, gaming, GPS mapping, operating systems, etc. Mobile devices are generally designed for mobility so that a user can carry and interact with such devices in everyday situations (e.g., a smart phone may be designed to fit within a pocket, a tablet may be designed to be held in a single hand, etc.). Unfortunately, the limited size of mobile devices, such as diminutive screens and buttons, may mar the user experience. In one example, web pages may be redesigned with reduce content in order for the web pages to fit within the viewing confines of mobile devices. In another example, a user may be restricted to miniature input devices, such as small keyboards, for interacting with content on a mobile device. 
     SUMMARY 
     This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key factors or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. 
     Among other things, one or more systems and/or techniques for monitoring interactions with a projected interactive interface are disclosed herein. In particular, an input object and an interface object may be identified and tracked in real-time within an environment. In one example, the input object and/or the interface object may be tangible objects within a physical environment (e.g., a finger input object and a notepad interface object within an outdoor or indoor space, such as a room). The input object and/or interface object may be tracked by iteratively indentifying such objects within the environment based upon depth data (e.g., depth data derived from depth based images of the environment successively captured by a depth camera). For example, the input object and/or interface object may be identified by calculating depth derivative characteristics derived from depth maps associated with captured images of the environment. That is, a depth camera may capture an image comprising depth measurements for pixels within the captured image, which may be represented as a depth map. Depth derivative characteristics may be calculated from the depth map by calculating the derivative change in depth between pixels and/or groups of pixels (e.g., an amount of change in depth between pixels), which may be used to create a depth derivative image. For example, a finger input object may be identified based upon depth derivative characteristics representing a cylindrical object having dimensional boundaries similar to a finger. 
     An interactive interface may be projected onto the interface object. It may be appreciated that the interactive interface may be associated with any one or more of a wide variety of interfaces, such as an email application, a calculator, a keyboard, a watch, a color pallet, a drawing surface, etc. It may be appreciated that the interface object may be associated with any one or more of a wide variety of tangible objects, such as a body part (e.g., a palm), a fixed surface in the environment (e.g., a wall), a hand-held object (e.g., a notepad), etc. In one example, the interactive interface may be projected onto the interface object using a projector, such as a pico projector. The projection may be dynamically adjusted in real-time based upon distortion of the interface object to provide a desired (e.g., optimal) viewpoint of the interactive interface (e.g., an interactive interface may be resized and/or repositioned based upon changes and/or movement of the interface object upon which the interactive interface is projected). 
     It may be appreciated that the input object and the interface object (and/or the interactive interface projected onto the interface object) may be tracked with respect to one another in real-time within the environment. In one example, the input object may be tracked to determine whether the input object is in a hover state or a touch state in relation to the interface object (and/or a portion of the projected interactive interface) based upon depth data (e.g., depth measurements, depth derivative characteristics, and/or other depth data). For example, a calculator interactive interface may be projected onto a left forearm interface object. The left forearm interface object and a right finger input object may be identified and/or tracked with respect to one another within the environment based upon depth data. The right finger input object may be determined to be in a hover state if the difference in depth between the right finger input object and the left forearm interface object is greater than a predetermined threshold. The right finger input object may be determined to be in a touch state if the difference in depth between the right finger input object and the left forearm interface object is less than a predetermined threshold. If the right finger input object is in a touch state, then a corresponding touch event may be invoked. For example, the touch state may indicate that the right finger input object is touching a sum button “+” on the calculator interactive interface projected onto the left forearm interface object. A touch event that displays a sum of two previously entered numbers may be calculated and/or displayed within a calculator display region of the calculator interactive interface object projected onto the left forearm interface object. 
     To the accomplishment of the foregoing and related ends, the following description and annexed drawings set forth certain illustrative aspects and implementations. These are indicative of but a few of the various ways in which one or more aspects may be employed. Other aspects, advantages, and novel features of the disclosure will become apparent from the following detailed description when considered in conjunction with the annexed drawings. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a flow chart illustrating an exemplary method of monitoring interactions with a projected interactive interface. 
         FIG. 2  is a flow chart illustrating an exemplary method of monitoring interactions between an input object and an interface object. 
         FIG. 3  is a component block diagram illustrating an exemplary system for monitoring interactions between an input object and an interface object. 
         FIG. 4A  is an illustration of an example of a stylus input object in a hover state with respect to a phone interactive interface projected onto a notepad interface object. 
         FIG. 4B  is an illustration of an example of a stylus input object in a touch state with respect to a phone interactive interface projected onto a notepad interface object. 
         FIG. 5  is an illustration of an example of monitoring a touch input on a color selection interactive interface projected onto a hand interface object, and then a stroke input on a marker board interactive interface projected onto a wall interface object. 
         FIG. 6A  is an illustration of an example of a finger input object in a hover state. 
         FIG. 6B  is an illustration of an example of a finger input object in a touch state. 
         FIG. 7  is an illustration of an example of a depth map associated with a stylus input object in a hover state with regard to a notepad interface object. 
         FIG. 8  is an illustration of an example of a depth map associated with a stylus input object in a touch state with regard to a notepad interface object. 
         FIG. 9  is an illustration of an exemplary computer-readable medium wherein processor-executable instructions configured to embody one or more of the provisions set forth herein may be comprised. 
         FIG. 10  illustrates an exemplary computing environment wherein one or more of the provisions set forth herein may be implemented. 
     
    
    
     DETAILED DESCRIPTION 
     The claimed subject matter is now described with reference to the drawings, wherein like reference numerals are generally used to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the claimed subject matter. It may be evident, however, that the claimed subject matter may be practiced without these specific details. In other instances, structures and devices are illustrated in block diagram form in order to facilitate describing the claimed subject matter. 
     Due to the limited mobility of general computing devices and the constrained screen and input size of mobile devices, it may be advantageous to provide users with additional interfaces through which a user may interact with a computing environment. In particular, a user&#39;s environment may be augmented with a projection of an interactive interface that may be used to interact with a computing environment. For example, an email interactive interface may be projected onto a surface (e.g., a hand, a wall, a tree, etc.), such that a user may read emails by interacting with the projection of the email application interface. Unfortunately, it may be difficult to monitor interactions of an input device (e.g., a fingertip) with an interactive interface projected onto an interface object due to limited information and/or feedback of the environment, input device, and/or interface object. For example, one current solution measures mechanical energy and/or sound waves created by impact of a finger on a surface. However, such a technique may be unable to detect whether the finger is moved along the surface, such as to create a finger stroke. 
     Accordingly, one or more systems and/or techniques for monitoring interactions with a projected interactive interface are provided herein. In particular, an input object and an interface object upon which an interactive interface may be projected may be tracked in real-time within an environment based upon depth data (e.g., depth measurements and/or calculated depth derivative data associated with images captured by a depth camera). Interactions, such as hovering over and/or touching, between the input object and the interface object may be tracked based upon such depth data. In this way, a user may interact with a computing environment through the interactive interface (e.g., a calculator) projected onto the interface object (e.g., a wall) using the input object (e.g., a finger) based upon depth data, which may be derived from images captured by a depth camera, for example. The user may appropriate a wide variety of surfaces as the interface object upon which the interactive interface may be projected (e.g., a wall, a palm, a door, etc.). For example, a user may invoke and/or define an interface object using a hand gesture. The projection of the interactive interface on the interface object may be tracked and/or dynamically adjusted based upon distortion, such as movement, of the interface object (e.g., a projection of an email application on a notepad interface object may be altered based upon a user moving or twisting the notepad interface object). 
     One embodiment of monitoring interactions with a projected interactive interface is illustrated by an exemplary method  100  in  FIG. 1 . At  102 , the method starts. At  104 , an input object and/or an interface object may be tracked in real-time within an environment. The tracking may comprise iteratively identifying the input object and interface object within the environment based upon depth derivative characteristics derived from depth maps associated with captured images of the environment. For example, a depth camera (e.g., a depth camera worn by a user) may be configured to capture images of the environment, along with depth data (e.g., depth data for respective pixels of an image), which may be used to generate depth maps of the environment. It may be appreciated that a wide variety of depth sensing techniques may be used to generate the depth map, such as LIDAR, time of flight, structured light techniques, and/or other depth sensing techniques. Depth derivatives (e.g., change in depth) may be calculated from the depth maps to indentify the input object and/or the interface object. In particular, the depth derivatives may be analyzed to identify clusters of pixels having depth derivative characteristics illustrative of input objects and/or interface objects. In one example, segmentation may be performed to identify the input object, which may yield spatial location (X, Y, and Z coordinates) of the input object (e.g., the input object may be segmented from other objects within the environment based upon depth data). 
     In one example of identifying an input object, a cylindrical input object may be identified based upon depth derivatives (changes in depth within the environment) illustrative of a cylindrical object having particular depth derivative characteristics. For example, a vertical cylinder may have depth derivative characteristics of a smooth derivative indicating small or no change in depth for an area to the left of the cylinder, then a steep positive derivative indicating a significant increasing change in depth for a curved left portion of the cylinder, then a smooth derivative indicating small or no change in depth for the top of the cylinder, then a steep negative derivative indicating a significant decreasing change in depth for a curved right portion of the cylinder, and finally a smooth derivative indicating small or no change in depth for an area to the right of the cylinder. In this way, a wide variety of input objects with various shapes having corresponding depth derivative characteristics may be identified. 
     At  106 , an interactive interface may be projected onto the interface object. In one example, a fixed-sized interactive interface may be projected at a fixed projection location (e.g., a center of a projection area on the interface object), such that the interface object would have to be positioned into the fixed projection location. In another example, an X/Y/Z location and orientation of the interface object may be determined so that the projection of the interactive interface may track the interface object. In another example, depth, size, and/or other measurement data of the interface object may be used to classify the interface object as a particular predefined type of surface (e.g., depth, size, and/or dimensional ranges may be predefined for various surfaces, which may be compared with measured data of the interface object to classify the interface object). In another example, the projection of the interactive interface may be automatically sized and/or positioned (e.g., auto-fitting) based upon available surface area detected on a segmented surface of the interface object. For example, X/Y/Z rotation estimates may be used to determine outermost points of the interface object&#39;s surface along major and minor axes, radiating out from the surface&#39;s central lock point, which may result in four lock points that may be used to estimate length and width of the interface object. In another example, a hybrid approach blending interface object classification and/or auto-fitting may be used. In another example, a user may define a projection area on the interface object upon which the interactive interface may be projected. For example, the user may click a center point and/or may drag a boundary outlining the projection area. It may be appreciated that a variety of projection and/or projection tracking techniques may be employed for projecting the interactive interface onto the interface object. 
     At  108 , the input object may be determined as being in a hover state or a touch state in relation to the interface object based upon depth data. That is, an X, Y, and Z position of the input object in relation to the interface object may be resolved in order to determine whether the input object is hovering above or touching the interface object (e.g., a portion of the interface object upon which (a portion of) the interactive interface is projected). In one example, the input object depicted within a depth map of the environment may be flood filled based upon depth values to determine whether the input object is in a hover state or a touch state. That is, pixels comprising similar depth values may be “flood filled” from the input object outward. If the flood filling fills at least a portion (e.g., a predefined percentage) of the interface object (e.g., because pixels within the interface object have similar depth values as pixels within the input object), then the input object may be determined as being in a touch state with regard to the interface object because of the similar depth values of the input object and the interface object. Additionally, if the touch location corresponds to a projected portion of the interactive interface, then an event associated with the (touched portion of the) interactive interface may be performed. However, if the flood filling does not fill at least a portion (e.g., a predefined percentage) of the interface object (because pixels within the interface object do not have similar depth values as pixels within the input object), then the input object may be determined as being in a hover state with regard to the interface object because of the dissimilar depth values of the input object and the interface object. At  110 , the method ends. 
     One embodiment of monitoring interactions between an input object and an interface object is illustrated by an exemplary method  200  in  FIG. 2 . At  202 , the method starts. At  204 , a depth map comprising depth data for pixels within a captured image of an environment may be received. At  206 , a depth derivative image may be generated from the depth map based upon computing depth derivatives for pixel clusters within the captured image using the depth data. That is, depth derivatives may be calculated in the X- and Y-axes for pixel clusters (e.g., a sliding 5×5 pixel window). The depth derivative image may be iterated over to identify an input object and/or an interface object. For example, template matching with dynamic parameters may be used to identify groupings of pixels that may be candidates for input objects and/or interface objects. 
     At  208 , the depth derivative image may be iterated over to identify an input object having depth derivative characteristics within predefined input object parameters. That is, predefined input object parameters may be predefined (e.g., as predefined templates) for various input objects that may be identified and/or tracked within an environment (e.g., a predefined template for a finger may be defined with input object parameters comprising a height range of 5 mm to 25 mm representing a typical finger diameter; a predefined template for a stylus may be defined with input object parameters typical of a stylus; etc.). A grouping of pixels may be identified as an input object candidate based upon the grouping of pixels comprising depth derivative characteristics within predefined input object parameters (e.g., vertical slices of cylinder-like objects may be identified as candidates for a finger input object). In this way, an input object may be identified based upon depth data, such as depth derivative characteristics and/or other depth information. 
     At  210 , the depth derivative image may be iterated over to identify an interface object having depth derivative characteristics within predefined interface object parameters. It may be appreciated that the input object and the interface object may be distinguishable from one another, and thus may be identified and/or tracked in real-time within the environment with relation to one another (e.g., the input object may be in a hover state or a touch state in relation to the interface object, the input object may be used to create a stroke input across the interface object, etc.). In particular, the input object and the interface object may be tracked in real-time within the environment by iteratively receiving depth maps comprising depth data for pixels within captured images of the environment, generating depth derivative images from the depth maps, and distinguishing between the input object and the interface object based upon depth data. 
     In one example, an interactive interface may be projected onto the interface object so that a user may interact with the interactive interface using the input object. The projection of the interactive interface may be dynamically adjusted (e.g., resized, moved, etc.) based upon distortion (e.g., movement) of the interface object, which may be detected from depth data associated with the interface object (e.g., depth data of a hand interface object may indicate that the hand moved to the right). In this way, interactions with the interactive interface may be monitored by tracking interactions of the input object with the interface object (e.g., the input object may touch a portion of the interface object upon which the interactive interface is projected, which may invoke a corresponding event associated with the interactive interface). 
     It another example, the input object and/or the interface object may be identified and/or tracked within the environment without reference or regard to an interactive interface and/or a projection thereof (e.g., a projected interface object may or may not be utilized when tracking input objects and/or interface objects). That is, the input object and the interface object may be tracked merely with respect to one another within the environment without having a projected interactive interface. For example, a finger may be identified as a finger input object, while a forearm may be identified as a forearm interface object. A user may enter a text message into a tangible computing device (e.g., a watch, cell phone, etc.) by “writing” the text message on the forearm interface object using the finger input object, which may be tracked as one or more touch states and/or one or more hover states between the finger input device and the forearm interface object. In this example, a projected interactive interface is not utilized (e.g., there is no projection of a text entry interactive interface on the forearm interface object). Thus, the user performs the text message entry by merely “writing” on a bare surface of the forearm (and, of course, other surfaces could be used). 
     Various states of the input object in relation to the interface object may be tracked based upon depth data (e.g., a flood filling technique based upon depth data may be used to determine whether the input object is touching or hovering above the interface object). For example, an input object may be in a hover state, a touch state, a touch state indicative of a stroke input, and/or a variety of other states in relation to the interface object. If the input object is in a touch state, then a corresponding touch event may be invoked. For example, if the input object is determined to be in a touch state in relation to the interface object at a location upon which the interactive interface is projected (e.g., a finger input object is touching an “s” key of a keyboard interactive interface projected onto a hand interface object), then an event corresponding to the interactive interface may be invoked (e.g., an “s” may be displayed in a projected text editing application associated with the projected keyboard interactive interface). Additionally, the projection of the interactive interface may be altered to provide real-time feedback (e.g., the “s” key of the keyboard interactive interface may be darkened, lightened, discolored, etc. to provide feedback that the “s” key was touched). If the input object is in a hover state (e.g., for X time), then a corresponding hover event may be invoked (e.g., an event corresponding to an interactive interface). 
     It may be appreciated that one or more input objects and/or one or more interface objects may be tracked within the environment. In one example, the depth derivative image may be iterated over to identify a second interface object (e.g., the first interface object may be a hand upon which a color pallet is projected, and the second interface object may be a wall upon which a drawing application is projected). A determination may be made as to whether the input object is in a hover state or a touch state in relation to the second interface object (e.g., a finger input object may be used to select a color from the color pallet projected on the first interface object, and then the finger input object may used to draw an image within the drawing application projected on the second interface object). In another example, the depth derivative image may be iterated over to identify a second input object (e.g., a first input object may be an index finger, and a second input object may be a pointer finger). A determination may be made as to whether the second input object is in a hover state or a touch state in relation to the interface object (e.g., the index finger may be used to invoke a shift key of a keyboard interactive interface projected onto a wall interface object, and the pointer finger may be used to invoke an “s” key of the keyboard interactive interface to create a capital S). At  212 , the method ends. 
       FIG. 3  illustrates an example of a system  300  configured to monitor interactions between an input object and an interface object. System  300  may comprise a projection component  312  and/or a tracking component  314 . The tracking component  314  may be configured to track an input object  306  (e.g., a stylus input object) and/or an interface object  304  (e.g., a notepad interface object) within an environment  302  (e.g., a room) by iteratively identifying the input object  306  and/or the interface object  304  within the environment  302  based upon depth derivative characteristics derived from depth maps  310  associated with captured images of the environment  302 . In one example, a depth camera may capture images of the environment  302 , which may be used as depth maps  310  comprising depth values for respective pixels of captured images. A depth derivative image may be generated from a depth map based upon computing depth derivatives for pixel clusters within a captured image using depth data of the depth map. The depth derivative image may be used to identify and/or track the input object  306  and the interface object  304 . In one example, the tracking component  314  may be configured to identify the interface object based at least in part upon a user hand gesture defining an interface area (e.g., a user may draw a box interface area upon a wall to define a box interface object on the wall). 
     The projection component  312  may be configured to project an interactive interface  308  (e.g., a calculator) onto the interface object  304 . The projection component  312  may be configured to dynamically adjust the projection of the interactive interface  308  based upon distortion of the interface object  304  detected from depth data associated with the interface object  304  (e.g., a user may twist or move the notepad interface object, and thus the projection of the calculator may be adjusted accordingly to provide desired (e.g., optimal) viewing; the user may tile the notepad interface object to indicate a desire for privacy, and thus the projection of the calculator may be dimmed or shrunken to provide privacy). 
     The tracking component  314  may be configured to determine whether the input object  306  is in a hover state or a touch state (or a touch state indicating a stroke input) in relation to the interface object  304  based upon depth data (e.g., depth values, depth derivative values, etc.). For example, the input object  306  may be flood filled within the depth derivative image (and/or a captured image and/or a depth map) based upon depth data (e.g., pixels having similar depth values may be “filled” from a starting point within the input object  306 , whereas pixels with dissimilar depth values may not be “filled”). In this way, the input object  306  may be determined as being in a touch state in relation to the interface object  304  (and potentially in a touch state in relation to a portion of the interactive interface  308  projected onto the touched area) based upon the flood filling at least a portion of the interface object. 
     It may be appreciated that the input object  306  may be determined as being in particular state, such as a touch state or a hover state, in relation to the interactive interface  308  projected onto the interface object  304 . For example, the input object  306  may be detected as being in a touch state in relation to the interface object  304  at a location upon which the interactive interface  308  is projected. Upon detecting the touch state, an event corresponding to the interactive interface  308  may be invoked (e.g., a call may be placed based upon detecting the input object  306  touched a “call” button on the interactive interface  308 ). Additionally, the projection of the interactive interface  308  may be altered to provide real-time feedback (e.g., the “call” button may be highlighted to provide feedback that the “call” button was touched and/or invoked). 
       FIG. 4A  illustrates an example  400  of a stylus input object  404  in a hover state with respect to a phone interactive interface  406  projected onto a notepad interface object  402 . The stylus input object  404  and notepad interface object  402  may be identified and/or tracked within an environment with respect to one another. The phone interactive interface  406  may be projected onto the notepad interface object  402 , such that a user may interact with the phone interactive interface  406  using the stylus input object  404 . In one example, the stylus input object  404  may be determined to be in a hover state with respect to the notepad interface object  402  based upon depth data (e.g., depth values of the stylus input object  404  may be dissimilar from depth values of the notepad interface object  402 ). Additionally, the stylus input object  404  may be determined to be in a hover state with respect to the phone interactive interface  406  (e.g., the stylus input object  404  may be determined to be hovering over a projection of the “9” button). 
       FIG. 4B  illustrates an example  410  of a stylus input object  414  in a touch state with respect to a phone interactive interface  416  projected onto a notepad interface object  412 . The stylus input object  414  and notepad interface object  412  may be identified and/or tracked within an environment with respect to one another. The phone interactive interface  416  may be projected onto the notepad interface object  412 , such that a user may interact with the phone interactive interface  416  using the stylus input object  414 . In one example, the stylus input object  414  may be determined to be in a touch state with respect to the notepad interface object  412  based upon depth data (e.g., depth values of the stylus input object  414  may be similar to depth values of the notepad interface object  412 ). Additionally, the stylus input object  414  may be determined to be in a touch state with respect to the phone interactive interface  416  (e.g., the stylus input object  414  may be determined as touching a projection of the “9” button). In one example, an event corresponding to the touch state may be invoked (e.g., the number “9” may be dialed within a phone application associated with the phone interactive interface  416  and/or the number “9” may be projected onto the interface object  412  within a dialing text box). In another example, the projection of the phone interactive interface  416  may be altered (e.g., the “9” button may be shaded grey to provide feedback that the number “9” was dialed). 
       FIG. 5  illustrates an example  500  of monitoring a touch input  512  on a color selection interactive interface  506  projected onto a hand interface object  502 , and then a stroke input  510  on a marker board interactive interface  504  projected onto a wall interface object  514 . A stylus input object  508 , the hand interface object  502 , and/or the wall interface object  514  may be identified and/or tracked within an environment with respect to one another. The color selection interactive interface  506  may be projected onto the hand interface object  502 , and the marker board interactive interface  504  may be projected onto the wall interface object  514 . In this way, interactions between the stylus input object  508  and the color selection interactive interface  506  and/or the marker board interactive interface  504  may be monitored (e.g., touch input  512 , stroke input  510 , etc.). 
     In one example, the stylus input object  508  may be determined to be in a touch state (touch input  512 ) with regard to the hand interface object  502  and/or a “blue selection” button of the color selection interactive interface  506 . Accordingly, a color selection event may be invoked based upon the touch input  512  (e.g., a drawing color of the marker board interactive interface  504  may be set to blue). Next, the stylus input object  508  may be determined to be in a touch state (stroke input  510 ) with regard to the wall interface object  514  and/or portions of the marker board interactive interface object  504 . Accordingly, a draw event may be invoked based upon the stroke input  510  (e.g., a blue line may be projected onto the wall interface object  514 ). 
       FIG. 6A  illustrates an example  600  of a finger input object  604  in a hover state  606 . The finger input object  604  may be indentified and tracked as an input object within an environment. Similarly, a palm interface object  602  may be indentified and tracked as an interface object within the environment. The palm interface object  602  and the finger input object  604  may be tracked with respect to one another in the environment. In one example, the finger input object  604  (e.g., a cluster of pixels representing the finger input object  604  within a capture image) may be flood filled based upon depth data to determine whether the finger input object  604  is in a touch state or a hover state (e.g., hover state  606 ). In particular, starting within the finger input object  604 , pixels having similar depth values may be filled. If a predetermined percentage of pixels representing the palm interface object  602  are not filled because such pixels have dissimilar depth values, then the finger input object  604  may be determined to be in the hover state  606  with respect to the palm interface object  602  (e.g., the finger input object  604  may be determined as hovering above the palm interface object  602  based upon the difference in depth between the finger input object  604  and the palm interface object  602 ). 
       FIG. 6B  illustrates an example  610  of a finger input object  614  in a touch state  616 . The finger input object  614  may be indentified and tracked as an input object within an environment. Similarly, a palm interface object  612  may be indentified and tracked as an interface object within the environment. The palm interface object  612  and the finger input object  614  may be tracked with respect to one another in the environment. In one example, the finger input object  614  (e.g., a cluster of pixels representing the finger input object  604  within a capture image) may be flood filled based upon depth data to determine whether the finger input object  614  is in a touch state (e.g., touch state  616 ) or a hover state. In particular, starting within the finger input object  614 , pixels having similar depth values may be filled. If at least a portion of pixels (e.g., a predetermined percentage of pixels) are filled, then the finger input object  614  may be determined to be in a touch state  616  with respect to the palm interface object  612  (e.g., flooding filling may attempt to fill as many pixels as possible from the finger input object  614  into the palm interface object  612 , such that if a predetermined percentage is filled, then the finger input object  614  and the palm interface object  612  are treated as merged, such as touching). In this way, a touch event may be invoked based upon the touch state  616  (e.g., an event associated with an interactive interface projected onto the palm interface object  612  may be invoked). 
       FIG. 7  illustrates an example  700  of a depth map  702  associated with a stylus input object  706  in a hover state with regard to a notepad interface object  704 . The depth map  702  may correspond to a captured image of an environment (e.g., a room with a user holding a notepad and a stylus). The depth map  702  may comprise depth data for respective pixels within the captured image (e.g., a depth of 20 units, a depth of 7 units, a depth of 6 units, etc.). The stylus input object  706  and/or the notepad interface object  704  may be identified and/or tracked based upon depth data within the depth map  702  and/or other depth maps not illustrated (e.g., depth map  802  of  FIG. 8 ). In one example, a cluster of pixels comprising depth values around 7 to 8 units may be identified as the notepad interface object  704 , while a cluster of pixels comprising depth values around 4 to 6 units may be identified as the stylus input object  706  (pixels with depth values beyond 15 units may be disregarded as background). It may be appreciated that depth values of the notepad interface object  704  and/or the stylus input object  706  may change from depth map to depth map as the objects are moved around within the environment over time, and thus tracking of the objects may take into account such changes. 
     The stylus input object  706  may be determined to be in a hover state with respect to the notepad interface object  704  because depth values of the stylus input object  706  (e.g., depth values of 4 to 6) are dissimilar from depth values of the notepad interface object  704  (e.g., depth value of 8 for pixels within the notepad interface object  704  that are near to the stylus input object  706 ). 
       FIG. 8  illustrates an example  800  of a depth map  802  associated with a stylus input object  806  in a touch state with regard to a notepad interface object  804 . The depth map  802  may correspond to a captured image of an environment (e.g., a room with a user holding a notepad and a stylus). The depth map  802  may comprise depth data for respective pixels within the captured image. The stylus input object  806  and/or the notepad interface object  804  may be identified and/or tracked based upon depth data within the depth map  802  and/or other depth maps not illustrated (e.g., depth map  702  of  FIG. 7 ). In one example, a cluster of pixels comprising depth values around 7 to 8 units may be identified as the notepad interface object  804 , while a cluster of pixels comprising depth values around 7 to 8 units may be identified as the stylus input object  806 . It may be appreciated that other considerations may be taken into account when determining the state of the stylus input object  806  with respect to the notepad interface object  804 . For example, features (e.g., detected visual features, predefined features associated with the type of input object and/or interface object, and/or other observed data) may be used to identify and/or track the state of the stylus input object  806  with respect to the notepad interface object  804 . It may be appreciated that depth values of the notepad interface object  804  and/or the stylus input object  806  may change from depth map to depth map as the objects are moved around within the environment over time, and thus tracking of the objects may take into account such changes. 
     The stylus input object  806  may be determined to be in a touch state with respect to the notepad interface object  804  because depth values of the stylus input object  806  (e.g., depth values of 7 to 8) are similar to depth values of the notepad interface object  804  (e.g., depth value of 8 for pixels within the notepad interface object  804  that are near to the stylus input object  806 ). 
     Still another embodiment involves a computer-readable medium comprising processor-executable instructions configured to implement one or more of the techniques presented herein. An exemplary computer-readable medium that may be devised in these ways is illustrated in  FIG. 9 , wherein the implementation  900  comprises a computer-readable medium  916  (e.g., a CD-R, DVD-R, or a platter of a hard disk drive), on which is encoded computer-readable data  914 . This computer-readable data  914  in turn comprises a set of computer instructions  912  configured to operate according to one or more of the principles set forth herein. In one such embodiment  900 , the processor-executable computer instructions  912  may be configured to perform a method  910 , such as at least some of the exemplary method  100  of  FIG. 1  and/or at least some of exemplary method  200  of  FIG. 2 , for example. In another such embodiment, the processor-executable instructions  912  may be configured to implement a system, such as at least some of the exemplary system  300  of  FIG. 3 , for example. Many such computer-readable media may be devised by those of ordinary skill in the art that are configured to operate in accordance with the techniques presented herein. 
     Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims. 
     As used in this application, the terms “component,” “module,” “system”, “interface”, and the like are generally intended to refer to a computer-related entity, either hardware, a combination of hardware and software, software, or software in execution. For example, a component may be, but is not limited to being, a process running on a processor, a processor, an object, an executable, a thread of execution, a program, and/or a computer. By way of illustration, both an application running on a controller and the controller can be a component. One or more components may reside within a process and/or thread of execution and a component may be localized on one computer and/or distributed between two or more computers. 
     Furthermore, the claimed subject matter may be implemented as a method, apparatus, or article of manufacture using standard programming and/or engineering techniques to produce software, firmware, hardware, or any combination thereof to control a computer to implement the disclosed subject matter. The term “article of manufacture” as used herein is intended to encompass a computer program accessible from any computer-readable device, carrier, or media. Of course, those skilled in the art will recognize many modifications may be made to this configuration without departing from the scope or spirit of the claimed subject matter. 
     It may be appreciated that at least one of A and B and/or the like generally means A or B or both A and B. 
       FIG. 10  and the following discussion provide a brief, general description of a suitable computing environment to implement embodiments of one or more of the provisions set forth herein. The operating environment of  FIG. 10  is only one example of a suitable operating environment and is not intended to suggest any limitation as to the scope of use or functionality of the operating environment. Example computing devices include, but are not limited to, personal computers, server computers, hand-held or laptop devices, mobile devices (such as mobile phones, Personal Digital Assistants (PDAs), media players, and the like), multiprocessor systems, consumer electronics, mini computers, mainframe computers, distributed computing environments that include any of the above systems or devices, and the like. 
     Although not required, embodiments are described in the general context of “computer readable instructions” being executed by one or more computing devices. Computer readable instructions may be distributed via computer readable media (discussed below). Computer readable instructions may be implemented as program modules, such as functions, objects, Application Programming Interfaces (APIs), data structures, and the like, that perform particular tasks or implement particular abstract data types. Typically, the functionality of the computer readable instructions may be combined or distributed as desired in various environments. 
       FIG. 10  illustrates an example of a system  1010  comprising a computing device  1012  configured to implement one or more embodiments provided herein. In one configuration, computing device  1012  includes at least one processing unit  1016  and memory  1018 . Depending on the exact configuration and type of computing device, memory  1018  may be volatile (such as RAM, for example), non-volatile (such as ROM, flash memory, etc., for example) or some combination of the two. This configuration is illustrated in  FIG. 10  by dashed line  1014 . 
     In other embodiments, device  1012  may include additional features and/or functionality. For example, device  1012  may also include additional storage (e.g., removable and/or non-removable) including, but not limited to, magnetic storage, optical storage, and the like. Such additional storage is illustrated in  FIG. 10  by storage  1020 . In one embodiment, computer readable instructions to implement one or more embodiments provided herein may be in storage  1020 . Storage  1020  may also store other computer readable instructions to implement an operating system, an application program, and the like. Computer readable instructions may be loaded in memory  1018  for execution by processing unit  1016 , for example. 
     The term “computer readable media” as used herein includes computer storage media. Computer storage media includes volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions or other data. Memory  1018  and storage  1020  are examples of computer storage media. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, Digital Versatile Disks (DVDs) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can be accessed by device  1012 . Any such computer storage media may be part of device  1012 . 
     Device  1012  may also include communication connection(s)  1026  that allows device  1012  to communicate with other devices. Communication connection(s)  1026  may include, but is not limited to, a modem, a Network Interface Card (NIC), an integrated network interface, a radio frequency transmitter/receiver, an infrared port, a USB connection, or other interfaces for connecting computing device  1012  to other computing devices. Communication connection(s)  1026  may include a wired connection or a wireless connection. Communication connection(s)  1026  may transmit and/or receive communication media. 
     The term “computer readable media” may include communication media. Communication media typically embodies computer readable instructions or other data in a “modulated data signal” such as a carrier wave or other transport mechanism and includes any information delivery media. The term “modulated data signal” may include a signal that has one or more of its characteristics set or changed in such a manner as to encode information in the signal. 
     Device  1012  may include input device(s)  1024  such as keyboard, mouse, pen, voice input device, touch input device, infrared cameras, video input devices, and/or any other input device. Output device(s)  1022  such as one or more displays, speakers, printers, and/or any other output device may also be included in device  1012 . Input device(s)  1024  and output device(s)  1022  may be connected to device  1012  via a wired connection, wireless connection, or any combination thereof. In one embodiment, an input device or an output device from another computing device may be used as input device(s)  1024  or output device(s)  1022  for computing device  1012 . 
     Components of computing device  1012  may be connected by various interconnects, such as a bus. Such interconnects may include a Peripheral Component Interconnect (PCI), such as PCI Express, a Universal Serial Bus (USB), firewire (IEEE 13104), an optical bus structure, and the like. In another embodiment, components of computing device  1012  may be interconnected by a network. For example, memory  1018  may be comprised of multiple physical memory units located in different physical locations interconnected by a network. 
     Those skilled in the art will realize that storage devices utilized to store computer readable instructions may be distributed across a network. For example, a computing device  1030  accessible via a network  1028  may store computer readable instructions to implement one or more embodiments provided herein. Computing device  1012  may access computing device  1030  and download a part or all of the computer readable instructions for execution. Alternatively, computing device  1012  may download pieces of the computer readable instructions, as needed, or some instructions may be executed at computing device  1012  and some at computing device  1030 . 
     Various operations of embodiments are provided herein. In one embodiment, one or more of the operations described may constitute computer readable instructions stored on one or more computer readable media, which if executed by a computing device, will cause the computing device to perform the operations described. The order in which some or all of the operations are described should not be construed as to imply that these operations are necessarily order dependent. Alternative ordering will be appreciated by one skilled in the art having the benefit of this description. Further, it will be understood that not all operations are necessarily present in each embodiment provided herein. 
     Moreover, the word “exemplary” is used herein to mean serving as an example, instance, or illustration. Any aspect or design described herein as “exemplary” is not necessarily to be construed as advantageous over other aspects or designs. Rather, use of the word exemplary is intended to present concepts in a concrete fashion. As used in this application, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or”. That is, unless specified otherwise, or clear from context, “X employs A or B” is intended to mean any of the natural inclusive permutations. That is, if X employs A; X employs B; or X employs both A and B, then “X employs A or B” is satisfied under any of the foregoing instances. In addition, the articles “a” and “an” as used in this application and the appended claims may generally be construed to mean “one or more” unless specified otherwise or clear from context to be directed to a singular form. Also, at least one of A and B and/or the like generally means A or B or both A and B. 
     Also, although the disclosure has been shown and described with respect to one or more implementations, equivalent alterations and modifications will occur to others skilled in the art based upon a reading and understanding of this specification and the annexed drawings. The disclosure includes all such modifications and alterations and is limited only by the scope of the following claims. In particular regard to the various functions performed by the above described components (e.g., elements, resources, etc.), the terms used to describe such components are intended to correspond, unless otherwise indicated, to any component which performs the specified function of the described component (e.g., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary implementations of the disclosure. In addition, while a particular feature of the disclosure may have been disclosed with respect to only one of several implementations, such feature may be combined with one or more other features of the other implementations as may be desired and advantageous for any given or particular application. Furthermore, to the extent that the terms “includes”, “having”, “has”, “with”, or variants thereof are used in either the detailed description or the claims, such terms are intended to be inclusive in a manner similar to the term “comprising.”