Patent Description:
A human body can be non-invasively examined using for example: penetrating photons (x-ray/CT, radio waves), electrical and magnetic fields (MRI), nuclear emissions (PET, Gamma camera), emitted and reflected photons (IR and visible light), ultra-sound (imaging/doppler) and electrical potential (EEG, EKG).

Such techniques are well known and in use, see for example <CIT> or <CIT>.

However, several of these techniques require large machines that can only be installed into hospitals or larger clinics. Also, devices using or triggering ionizing radiation like X-rays and PET, cannot be used on a large part of the population due to the side-effects of such radiation.

Speed is also of importance for a modelling system, since the test subject has limited ability to remain still for a longer period of time.

It is an objective of the present invention to provide an efficient and automated way of modelling a surface of a body by means of a 3D modelling device in combination with a camera.

According to the present invention, there is provided a camera module. The camera module comprises a 3D modelling device for obtaining respective distances to a plurality of adjacent parts of a surface of a body. The camera module also comprises a camera arrangement for acquiring images of the parts of the surface, wherein the camera arrangement comprises at least one camera. One or each of said at least one camera comprises a camera sensor for producing said images, a focusing lens for focusing light reflected on the surface of the body onto the camera sensor, and a movable mirror for sequentially directing light from each of said parts of the surface into the focusing lens. The camera module also comprises a housing enclosing both the 3D modelling device and the camera arrangement. The focusing lens is automatically controllable to set a focus of the camera based on the obtained distances.

According to an embodiment of the present invention, there is provided a modelling system comprising a frame, and a plurality of the camera modules of the present disclosure, wherein the camera module are fixed in relation to each other on the frame. The modelling system is arranged to receive the body to be modelled.

According to another embodiment of the present invention, there is provided a method performed by an embodiment of the camera module of the present disclosure. The method comprises, by the 3D modelling device, obtaining the respective distances to the adjacent parts of the surface of the positioned body. The method also comprises sequentially, for each of the surface parts: automatically moving the mirror to direct light from the surface part into the focusing lens; by the focusing lens, during the moving of the mirror, automatically setting the focus on the surface part based on the obtained distance to said surface part; and, by the camera sensor, acquiring the image of the surface part.

According to another embodiment of the present invention, there is provided a computer program product comprising computer-executable components for causing a camera module to perform an embodiment of the method of the present disclosure when the computer-executable components are run on processing circuitry comprised in the camera module.

According to an aspect of the disclosure which is not part of the present invention, there is provided a method performed by an embodiment of the modelling system of the present disclosure. The method comprises, by the 3D modelling devices of the camera modules, obtaining a system-wide topographic model of the surface of the body positioned in relation to the modelling system. The method also comprises, based on the obtained topographic model, defining a respective surface section for the at least one camera of each of the camera modules. The method also comprises, to each of the camera modules, sending information about the respective surface section defined for the at least one camera of said camera module.

By including the 3D modelling device and the camera arrangement in the same module, enclosed in a common housing, they are arranged in a fixed spatial relationship to each other, with a known and small parallax between the 3D modelling device and a camera in the camera arrangement. Also, handling is improved by packaging the different devices and cameras in a module which can be handled as a single part. The module can be arranged for modelling a section of the body surface, made up of the plurality of adjacent surface parts. The modelling may include acquiring a full image of the surface of the body, typically stitched together from images acquired of the different parts of the surface, assisted by the distances obtained by the 3D modelling device. The obtained distances may e.g. be used to form a point cloud or other spatial model of the body surface, onto which the acquired images may be overlayed during modelling of the surface of the body. A plurality of modules can easily be arranged on a frame, in a fixed spatial relationship to each other, to form the modelling system, where each module is arranged to model a section of the body surface, where the sections may together cover the whole surface of the body, or a side thereof, e.g. a front side or a back side of the body.

<FIG> illustrates how visible and thermal photons can be collected by a modelling system <NUM> for a standing test subject positioned, preferably immovably, in relation to the modelling system. To simplify the figure, only the cameras and light emitters mounted on the remote pillars of the frame <NUM> are drawn. In reality any of the pillars or other structural elements of the frame <NUM> may carry the cameras and/or light emitters. As discussed herein, some or all of a 3D modelling device, e.g. a 3D or depth camera such as a structured-light scanner <NUM> and/or time-of-flight camera and/or a stereo camera e.g. with a structured light or random dot projector, a visible-light camera <NUM>, typically a colour camera, a thermal camera <NUM> and/or light emitters <NUM> may be combined in a camera module <NUM> (see <FIG> and <FIG>) for improved modelling of a body of a subject. A plurality of modules <NUM> may be used to cover a larger part of the body B, or the whole body.

A 3D modelling device, e.g. a structured-light scanner <NUM> (as exemplified herein) and/or a time-of-flight camera and/or a stereo camera or other 3D or depth camera, is used to obtain distances to different parts of a surface of the body B, typically a surface of the skin of a live human or animal body, but possibly at least partly of hair or clothes on top of the skin. These distances may form, or form part of, a spatial 3D model of the body B. The spatial model, e.g. comprising a point cloud, may be acquired using a structured light 3D scanner <NUM>. Such a device <NUM> comprises a structured light projector and a camera. The camera records the different light patterns projected on the body by the projector and can construct a 3D model, e.g. point cloud, based on this information. An example of such a commercially available camera is the Ajile DepthScan™ 3D imaging system. The structured light 3D scanner is further illustrated in <FIG> and <FIG>.

By means of the spatial model, e.g. comprising or consisting of a point cloud representing the skin surface of the body, any acquired visual-light images, thermal images etc. can be accurately related in space (i.e. spatially) to the body, allowing the body to be modelled with the acquired images. A point cloud can be used, or based upon, by correlating information (images, measurements etc.) to a common coordinate system of the body provided by the point cloud. Such correlated information can then be a source for scheduling camera focus and/or point of view.

The spatial model is limited to the field of view of the 3D modelling device <NUM>. In <FIG>, a single 3D modelling device <NUM> is shown. However a plurality of such devices <NUM>, typically in respective camera modules <NUM>, may be positioned, e.g. on all the pillars, around the body to capture the entire body.

It may additionally or alternatively be possible to use a passive model/point cloud acquisition system using multiple wide field of view cameras <NUM> as 3D modelling devices for obtaining the distances to the surface parts. Using two or more of these cameras <NUM>, it is possible to construct a model/point cloud using photogrammetry analysis.

In another embodiment it is possible to combine 3D model data acquired from the structured light scanner <NUM> with data from the wide view cameras <NUM>, to create a combined 3D model including the distances to the surface parts. In <FIG>, the structured light scanner <NUM> can observe the coronal plane viewing the chest and head areas. The model of the remainder of the body may be covered by the photogrammetry analysis using the wide view cameras <NUM>.

In another embodiment it is possible to use a camera with time-of-flight measurements to acquire the model and thus the distances to the surface parts. Examples of such a camera is the Azure Kinect DK™ depth camera which continuously transmits an amplitude modulated continuous wave in the near infra-red spectrum onto the body and then records the time it takes for the light to travel from the camera to the body and back.

The visual-light camera, e.g. a high-resolution colour camera, <NUM> may have a narrow field of view and a shallow depth of field designed to take multiple overlapping surface/skin images with a high-resolution. A mirror may be used to select the desired field of view. A focusing device may then be used to take a stack of images using different focal distances for the selected field of view. The stack is then merged into a single image using a focal plane merging algorithm. The camera <NUM> for the visible light spectrum is further illustrated in <FIG>.

The visible-light camera <NUM> may need a significant amount of lighting to acquire high quality images why separate light emitters <NUM> may be used, e.g. the LED lighting in the figure.

Thermal camera <NUM> is an example of a thermal camera. Such a camera may have an appearance similar to the visible-light camera <NUM>, but high-quality thermal cameras are typically larger and significantly more expensive than a high-resolution colour camera. The thermal camera <NUM> is further illustrated in <FIG>.

A thermal camera <NUM> may view the front of the body B through direct thermal emissions <NUM>, but may additionally or alternatively view the back of the body through a reflection <NUM> in a glass panel/mirror <NUM>. For a body B of a standing subject, it may be preferable to be able to image both back and front simultaneously. A fast acquisition of thermal images may be important since the subject may move involuntarily when standing. Uncorrected movements can worsen the positional errors and the continuity of testing.

<FIG> illustrates how a spatial model, e.g. comprising a point cloud, as well as visible and thermal images may be acquired of a body B by the modelling system <NUM> for a lying subject. A camera module <NUM> may contain a light emitter <NUM>, a visible-light camera <NUM>, a thermal camera <NUM>, and/or a structured light scanner <NUM>. A plurality of modules <NUM> may be used. In the example of <FIG>, six modules <NUM> are positioned so as to cover one side (the front) of the body. Typically, during modelling of the body B, i.e. during the obtaining of the distances and during the acquiring of the images, each camera module <NUM> is arranged a suitable distance from the body, e.g. a distance within the range of <NUM>-<NUM>, such as within the range of <NUM>-<NUM>. The module, or modules, <NUM> may be mounted on the frame <NUM> of the modelling system <NUM>, in a fixed spatial relationship to both the body B and to each other (i.e. to other modules <NUM> in the modelling system <NUM>).

<FIG> illustrates an embodiment of a camera module <NUM> for model acquisition. In the example of <FIG>, the structured light scanner <NUM> is positioned behind the visible-light camera <NUM> to minimize the parallax errors between the structured light scanner <NUM> and the visible-light camera <NUM>. The light emitters <NUM> may be high-intensity LED light emitters. The thermal camera <NUM> may be positioned next to the visible-light camera <NUM>. The structured light scanner <NUM>, or other 3D modelling device, as well as the visible-light and/or thermal cameras <NUM> and <NUM> are enclosed in a housing <NUM> of the camera module <NUM>.

<FIG> schematically illustrates an embodiment of a camera module <NUM> of the present disclosure. The camera module <NUM> comprises processing circuitry <NUM> e.g. a central processing unit (CPU). The processing circuitry <NUM> may comprise one or a plurality of processing units in the form of microprocessor(s). However, other suitable devices with computing capabilities could be comprised in the processing circuitry <NUM>, e.g. an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or a complex programmable logic device (CPLD). The processing circuitry <NUM> is configured to run one or several computer program(s) or software (SW) <NUM> stored in a storage <NUM> of one or several storage unit(s) e.g. a memory. The storage unit is regarded as a computer readable means <NUM>, forming a computer program product together with the SW <NUM> stored thereon as computer-executable components and may e.g. be in the form of a Random Access Memory (RAM), a Flash memory or other solid state memory, or a hard disk, or be a combination thereof. The processing circuitry <NUM> may also be configured to store data in the storage <NUM>, as needed. The camera module <NUM> may also comprise a communication interface for communicating with entities external to the module <NUM>, e.g. with a computer functioning as a controller of the modelling system <NUM>.

<FIG> illustrates a visible-light camera <NUM>, e.g. a high-resolution colour camera. Such a camera can comprise a movable mirror <NUM>, the movement of which may be controlled and actuated by means of electromagnetic force, e.g. my means of an actuator comprising a coil similar to a voice coil in a speaker. The mirror is used for selecting the part of the surface of the body B which should be imaged by allowing light from that part of the surface to be reflected on the mirror <NUM> and pass through the focusing lens <NUM> to the camera sensor <NUM>. The electronic camera sensor <NUM> is arranged to produce a digital image of the surface part as focused thereon by the focusing lens <NUM> via the mirror <NUM>.

The focusing lens <NUM>, e.g. an actuated lens, can be controlled by a computer e.g. using the model previously obtained by means of the 3D modelling device. In an embodiment, a scanning plan has been created to cover the whole body B of the subject, using multiple high-resolution cameras <NUM> of respective multiple camera modules <NUM>. This scanning plan may schedule the field of view (set by using and moving the mirror <NUM>) and the focus (set by using the lens <NUM>) in part based on the model (which may include individual features of the specific body) but also in part based on positions of the available cameras and the desired overlap to stitch the images. For each camera <NUM>, focusing can be speeded up by setting a new focus while the mirror <NUM> is still moving.

When the 3D structure of the surface part to be imaged is known, e.g. by means of the 3D modelling device <NUM>, for instance if the 3D modelling device provides a plurality of distances to each surface part to enable modelling of the topography of the surface part, the number of focus steps, and the distance therebetween (density), needed to cover the depth of focus desired may be calculated. For example, a skin segment with a higher variation of topography may require more focus steps (e.g. in combination with smaller pitches), and thus more stacked images, to resolve specific features. The topographic model may also be used to define the different, typically adjacent, surface parts. For example, if the field of view (FOV) of a camera in one of the camera modules <NUM> in the system <NUM> is occluded, as determined from the topographic model, then another one of the camera module(s) <NUM> in the system <NUM>, with an overlapping FOV but with a different angle to the surface part of interest may be used instead, to avoid the occlusion.

The first focus can be set at the same time as the mirror is moved to cover the surface part to minimize total scan time. The first focus may be set to slightly above the surface. When the mirror has been positioned, a series of consecutive stacked images may be taken, one (or more than one e.g. for super-resolution) per focus step, moving the focus further into the surface/skin, to capture a stack of images. The stack may then be merged by using a focal plane merging algorithm. Focal plane merging combines multiple images taken at different focus distances to give a resulting image with a depth of field greater than the depth of field available from the camera itself. The focal plane merging algorithm may use image features and their sharpness but also the 3D information of the surface part, e.g. from the 3D modelling device <NUM>, to improve quality of the merged image. High-speed focusing by the focusing lens <NUM> may be possible for the visible-light camera <NUM>, especially if it uses a liquid lens, which can change shape quickly. A liquid lens incorporates optical grade liquid in the middle of a cell structure and works more like the lens of an eye when able to change shape. Additionally or alternatively, a liquid lens can change focus by being moved to change its distance to the sensor, just like a regular solid lens. The liquid allows the lens itself to move and change shape, either mechanically or electronically, benefitting both focusing speed and the focal length that can be achieved.

The schedule based on the model can then be used to select the next field of view for the visible-light camera <NUM> to cover the next surface part of the test subjects body B. The known parallax between the structured light scanner <NUM> and the visible-light camera <NUM> may be used to stitch the image stacks into a full visible-light image of the surface/skin of the body. Any base overlap is known from the mirror position selected based on the model. The stitching may then be finetuned using the overlap between two image stacks, using for example optical flow, template matching or feature matching.

<FIG> illustrates a thermal camera <NUM>. Such a camera may comprise a movable mirror <NUM>, e.g. a metal mirror suitable for infrared light, the movement of which mirror may be controlled and actuated by means of electromagnetic force, e.g. my means of an actuator comprising a coil similar to a voice coil in a speaker. As for the visible-light camera <NUM>, the mirror may be used for selecting the part of the body surface which should be imaged and infrared light from that part of the surface is reflected on the mirror <NUM> to pass through the focusing lens <NUM> to the thermal camera sensor <NUM>. Alternatively, the thermal camera may have a wider field of view not requiring a movable mirror.

In contrast to the visible-light camera, infrared light cannot be focused using liquid lenses. Thus, the focusing lens <NUM> of the thermal camera typically comprises movable solid, e.g. glass, lenses and the focusing time is longer. This makes it even more advantageous to use the obtained distances to the surface parts to set the desired focus depth before a thermal image is taken. The thermal images are not stacked and it speeds up the acquisition time if a thermal image is being correctly focused while the mirror <NUM> is moved. The discussion above for a visible-light camera <NUM> relating to stacked images may also be relevant to some embodiments the thermal camera <NUM>.

<FIG> illustrates a 3D modelling device <NUM>, e.g. a 3D or depth camera such as comprising a structured-light scanner and/or time-of-flight camera and/or a stereo camera e.g. with a structured light or random dot projector. Herein, the 3D modelling device <NUM> is exemplified with a structured-light scanner. The structured light scanner <NUM> comprises a camera <NUM> and structured light projector <NUM>. The structured light scanner <NUM> may be mounted on the fixture <NUM> of the camera module <NUM>. High-intensity light-emitters <NUM> may be mounted on the same fixture. The fixture may be mounted on a structural support beam <NUM>.

In some embodiments, the 3D modelling device <NUM> of each, or at least one of, the camera modules <NUM> in the modelling system <NUM>, or an additional imaging system in the modelling system <NUM> but external to the camera modules <NUM>, may comprise a low-resolution, and thus higher FOV, 3D imaging system, e.g. operating in a non-visible light spectrum, which system may operate during the acquiring of images of the surface of the body B. By means of the low-resolution 3D imaging system, body movements between image acquisition of different surface parts (with any camera <NUM> and/or <NUM> in the camera module <NUM>) may be compensated for. Also stitching together of the sequentially acquired images may be facilitated. Such an additional imaging system may comprise several 3D cameras, typically less than the number of camera modules <NUM> in the modelling system <NUM>.

<FIG> is a flow chart illustrating a method of the present invention. The method is performed by a camera module <NUM> of the present disclosure. Prior to the performing of the method, the body B may be positioned S1 in relation to the camera module <NUM>, e.g. by moving the body and/or the camera module. The method comprises, by the 3D modelling device <NUM>, obtaining S2 the respective distances to the adjacent parts of the surface of the body B positioned S1 in relation to the camera module <NUM>. The method then further comprises sequentially S3, for each of the surface parts: automatically moving S31 the mirror <NUM> and/or <NUM> to direct light from the surface part into the focusing lens <NUM> and/or <NUM>; by the focusing lens <NUM> and/or <NUM>, during the moving S31 of the mirror <NUM> and/or <NUM>, automatically setting S32 the focus on the surface part based on the obtained S2 distance to said surface part; and, by the camera sensor <NUM> and/or <NUM>, acquiring S33 the image of the surface part. Preferably, each of the acquired S33 images extends some distance around the surface part, resulting in an overlap between the images which may facilitate stitching S4 to obtain a sectional image of the section of the body surface covered by the camera <NUM> and/or <NUM>. In some embodiments, the method further comprises stitching S4 the sequentially S3 acquired S33 images to acquire a sectional image of the surface of the body B.

In some embodiments of the present invention, the obtaining S2 of the distances comprises, for each of the surface parts, obtaining a plurality of distances to the surface part and obtaining the spatial model, at least in part, by modelling a topography of the surface part based on said plurality of distances. Then, in some embodiments, the setting S32 of the focus comprises setting the focus based on said topographic model. In some embodiments, the setting S32 of the focus comprises calculating the number of distances of said plurality of distances to which the focus is set, and/or the focus pitch(es) therebetween, based on the topographic model of the surface part. Additionally or alternatively, in some embodiments, the obtaining S2 of the respective distances comprises defining the surface parts based on the topographic model.

Regarding the system <NUM> comprising a plurality of camera modules <NUM>, each module <NUM> may be arranged for acquiring S33 the images of the different parts of a respective section of the surface of the body B. The respective sections of the modules may be overlapping, and as with the different parts of each section, also the sectional images may be stitched together to form a system-wide image, typically overlayed on a similarly stitched together spatial model of the surface of the body.

The system <NUM> may be arranged with modules <NUM> with respective overlapping sections covering at least <NUM>° of the body B, typically a front or back side of the body. To obtain a full body image covering the whole surface of the body, the body B, or the system <NUM>, may then have to be turned <NUM>° once and the two system-wide images may be stitched together. Any suitable number of modules <NUM> may be comprised in the system <NUM>, e.g. to cover a front or back side of the body B, such as a number of modules <NUM> within the range of <NUM>-<NUM> modules <NUM>. In a currently preferred embodiment, nine modules <NUM> are comprised in the system <NUM>, e.g. arranged in a 3x3 matrix.

As mentioned above, a topographic model may be obtained for each module <NUM> by means of the 3D modelling device <NUM> of said module <NUM>. Similarly to the stitching together of different sectional images to form a system-wide image, also the topographic model for each section (i.e. obtained S2 by each module <NUM>) may additionally or alternatively be stitched together to form a system-wide topographic model, e.g. covering a front or back side of the body B. In some examples, this system-wide topographic model may be used to define the respective sections of the camera(s) <NUM> and/or <NUM> of each of the modules <NUM>, i.e. defining the borders of the section divided into the adjacent parts of which images are acquired S33. This enables accounting for individual differences of each body B to which the system <NUM> is applied, specifically differently shaped bodies B. Due to different shapes of bodies B, the field of view of a camera <NUM> or <NUM> may differ from one body to another, e.g. due to occlusion as mentioned above, and the respective sections covered by the different modules <NUM> may be adjusted accordingly for each body B.

Additionally or alternatively, a low-resolution 3D imaging system (as mentioned above) may be used for obtaining the system-wide topographic model. The low-resolution 3D imaging system typically has a larger field of view (FOV) than the 3D modelling devices <NUM> which typically have a higher resolution. For instance, the low-resolution 3D imaging system may be used for defining respective surface sections of the body for the 3D modelling device <NUM> of each module <NUM>, and the stitched-together system-wide topographic model obtained from the 3D modelling devices <NUM> may be used for adjusting said sections to sections for the camera(s) <NUM> and/or <NUM> of each of the modules <NUM>. The sections are preferably overlapping to facilitate stitching. Additionally or alternatively, the lower resolution 3D information obtained by means of the low-resolution 3D imaging system, which covers a larger part of the body surface than the 3D modelling devices <NUM> by virtue of its larger FOV, may be used to facilitate the stitching-together of the respective spatial or topographic models of the 3D modelling devices <NUM> to obtain the system-wide spatial or topographic model. Thus, the low-resolution 3D imaging system may provide a general map for stitching-together the sectional but higher-resolution spatial or topographic models of the 3D modelling devices <NUM>.

<FIG> illustrates some examples of a method performed by the system <NUM>. The method comprises, by the 3D modelling devices <NUM> of the camera modules <NUM>, obtaining S11 a system-wide topographic model of the surface of the body B positioned in relation to the modelling system <NUM>. Typically, respective topographic models of the 3D modelling devices <NUM> of all the camera modules <NUM> in the system <NUM> are stitched together to the system-wide topographic model. Based on the obtained S11 system-wide topographic model, a respective surface section for the at least one camera <NUM> and/or <NUM> of each of the camera modules <NUM> is defined S12. Thus, depending on the individual shape of the body B, the different sections of the body surface to be covered by the camera(s) of each module <NUM> may be defined. Then, information about the defined S12 sections are sent to the camera modules for use thereby, e.g. in accordance with the method discussed in relation to <FIG>, where the surface section assigned to a camera module is divided into the adjacent parts discussed therein. The obtaining S2 of the distances to the adjacent surface parts may typically be done as part of the obtaining S11 of the system-wide topographical model. Alternatively, the obtaining S2 of the distances to the adjacent surface parts may be done after the defining S12 of the sections and sending S13 of information thereof to the modules <NUM>.

In some examples, the obtaining S11 of the system-wide topographic model comprises obtaining the system-wide topographic model by means of a low-resolution 3D imaging system comprised in the modelling system <NUM>. Thus, a low-resolution 3D imaging system may be used in addition to the 3D modelling devices <NUM> of the camera modules <NUM>, e.g. as discussed above, to obtain the system-wide topographic model. The low-resolution 3D imaging system has a lower resolution and a larger field of view than each of the 3D modelling devices <NUM>.

Claim 1:
A camera module (<NUM>) comprising:
a 3D modelling device (<NUM>) for obtaining respective distances to a plurality of adjacent parts of a surface of a body (B);
a camera arrangement for acquiring images of the parts of the surface, wherein the camera arrangement comprises at least one camera (<NUM>; <NUM>) comprising:
a camera sensor (<NUM>; <NUM>) for producing said images,
a focusing lens (<NUM>; <NUM>) for focusing light reflected on the surface of the body (B) onto the camera sensor, and
a movable mirror (<NUM>; <NUM>) for sequentially directing light from each of said parts of the surface into the focusing lens; and
a housing (<NUM>) enclosing both the 3D modelling device and the camera arrangement;
wherein the focusing lens is adapted to automatically set the focus of the camera during the moving of the mirror based on the obtained distances, and
wherein the camera module (<NUM>) is mounted on a frame (<NUM>) for being in a fixed spatial relationship to the body (B).