Abstract:
An animation wireframe is modified with three-dimensional (3D) range data having a corresponding shape surface. The animation wireframe is scaled in a first direction based on distances between feature pair within the 3D range data and corresponding distances within the generic animation wireframe. The location of a first animation wireframe point is adjusted in a second direction to coincide with a point on the shape surface.

Description:
This is a continuation of application Ser. No. 08/867,727, filed on Jun. 3, 1997, now U.S. Pat. No. 5,969,721. 
    
    
     FIELD OF THE INVENTION 
     The present invention is generally directed to computer animation. Specifically, the present invention is directed to customizing a computer animation wireframe with three-dimensional range and color data. 
     BACKGROUND 
     Known systems can provide generic computer animations that integrate audio and visual information. For example, these generic computer animations typically display a talking head of a human or of a cartoon animal. These generic computer animations can be used for a number of applications. For example, some known systems display the computer animation on a computer video monitor to interface with a human user. Other known systems can convert ASCII (American Standard Code for Information Interchange) text into synthetic speech and synchronized talking-head video with realistic lip and jaw movements. 
     These known computer animations are based on a generic animation wireframe models. Although these generic animation wireframe models are generic in the sense that the animations do not represent a specific person; these generic models can be deformed according to a predefined set of parameters to vary the presentation from the one generic version. Deforming a generic animation wireframe model can be used to more closely resemble realistic and natural interactions, for example, human-to-human interactions. Deforming the generic model using a predefined set of parameters, however, cannot sufficiently modify the generic model to present actual people recognized by the viewer. 
     To produce more realistic and natural displays for human interactions, animation wireframe models should incorporate real measurements of the structure of the desired face, as well as color, shape and size. Such information can be obtained by a three-dimensional laser scanner system that scan a person&#39;s head to produce very dense range data and color data of the head. 
     Some known systems that incorporate measured three- dimensional information into generic animation wireframe models, however, suffer from several shortcomings. In general, accurately modifying generic animation wireframe models with measured three-dimensional range data requires extensive and expensive manual adjustments or automated computer-based adjustments. Manual adjustments of generic animation wireframe models can be time consuming and/or can require expensive human personal with specialized training. Automated adjustments of generic animation wireframe models can require expensive computer equipment that is generally cost-prohibitive for mass distribution and may require extensive maintenance performed by human personnel with specialized training. 
     SUMMARY OF THE INVENTION 
     The present invention modifies a generic animation wireframe model with measured three-dimensional range data to produce a customized animated wireframe. The present invention produces the customized animated wireframe without requiring extensive manual adjustments or elaborate computer equipment. 
     The present invention modifies an animation wireframe having multiple points with three-dimensional (3D) range data. The 3D range data has a corresponding shape surface. The animation wireframe is vertically scaled based on the distances between consecutive features within the 3D range data. For each animation wireframe point, the location of the animation-wireframe point is horizontally adjusted to correspond to a point on the shape surface within a horizontal plane. 
     The vertical scaling factors can be calculated based on the distances between certain points within the 3D range data. A primary point within the 3D range data corresponding to a first feature within the plurality of features can be obtained. A vertical alignment line based on the primary point can be obtained. Secondary points within the 3D range data corresponding to features that lie along the vertical alignment line can be obtained. Consequently, vertical scaling factors based on the distances between consecutive features can be calculated. 
     A tertiary point within the 3D range data can be selected to define a vertical cut-off plane. For each animation wireframe point, the origin point within the horizontal plane can also be defined. The primary point, the secondary points and the tertiary point can be obtained manually or automatically. 
     In one embodiment of the present invention, horizontal scaling can be performed by defining a scaling line within the horizontal plane. The scaling line can be defined as containing the animation-wireframe point and an origin point. A shape-surface point is determined as the intersection of the scaling line and the shape surface. The location of the animation-wireframe point can be adjusted to correspond to the shape-surface point. This process can be repeated for each wireframe-animation point. 
     In an alternative embodiment, horizontally scaling can be performed by selecting a pair of animation-wireframe points within the same horizontal plane and then defining two individual scaling lines. Two shape-surface points can be determined as the two scaling lines and the shape surface. The location of the two animation-wireframe points are then horizontally adjusted to correspond to the two shape-surface points. 
     Two animation-wireframe points can be adjusted so that L W ′/L W  substantially equals L R ′/L R′  where L W ′ is the length of a first line connecting the first animation wireframe point and the second animation wireframe point along the animation wireframe within the horizontal plane, L W  is the length of a second line along the animation wireframe within the horizontal plane, the second line being between the limit of the horizontal plane and a first intersection point where the animation wireframe within the horizontal plane intersects a perpendicular line containing the origin point and being perpendicular from the limit of the horizontal plane, L R ′ is the length of a third line connecting the first shape-surface point and the second shape-surface point along the shape surface within the horizontal plane, and L R  is the length of a fourth line along the shape surface within the horizontal plane, the fourth line being between the limit of the horizontal plane and a second intersection point where the shape surface within the horizontal plane intersects the perpendicular line. 
     Texture mapping can be provided to the animation wireframe based on color data corresponding to the 3D range data. In an alternative embodiment, an alignment point within the 3D range data can be obtained corresponding to an object within the animation wireframe that substantially moves during animation. The alignment point can be matched with the corresponding point within the animation wireframe. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 illustrates a system for customizing a computer animation wireframe according to an embodiment of the present invention. 
     FIGS. 2A and 2B illustrate an example of a generic animation wireframe that can be produced from generic animation wireframe data. 
     FIG. 3 illustrates an example of the generic animated wireframe with smooth shading. 
     FIGS. 4A and 4B illustrate an example of a display of based on measured three-dimensional range data. 
     FIGS. 5A and 5B illustrate a method for modifying the generic animation wireframe with the three-dimensional range and color data according to an embodiment of the present invention. 
     FIGS. 6A and 6B show an example of a display of the three-dimensional range data with the vertical profile line and with lines showing the primary point and the secondary points. 
     FIG. 7 illustrates the horizontal plane within which a selected animation-wireframe point is horizontally scaled according to an embodiment of the present invention. 
     FIG. 8 illustrates the horizontal plane within which a selected animation-wireframe point is horizontally scaled according to another embodiment of the present invention. 
     FIGS. 9A and 9B illustrate the fitted animation wireframe resulting from the modification of the generic animation wireframe using the three-dimensional range data. 
     FIG. 10 illustrates a resulting fitted animation wireframe with smooth shading in a front-view perspective. 
     FIG. 11 shows the resulting fitted animation wireframe with texture shading provided by the color information in the measured three-dimensional range and color data. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 illustrates a system for customizing a computer animation wireframe according to an embodiment of the present invention. Three-dimensional (3D) scanner system  100  is connected to wireframe processor station  110 . 
     3D scanner system  100  can be any type of range sensor system that produces 3D range and color data of an object, such as a human head. 3D scanner system  100  can include, for example, a low intensity laser source, a mirror assembly, an imaging optics subsystem, a CCD (charge coupled device) video range and color sensor, and supporting electronics. The supporting electronics can include a processor, a computer-readable memory and input port to be coupled to the CCD sensor and output port to be coupled to wireframe processor station  110  and a databus that connects the processor, the computer readable memory, the input port and the output port. An example of 3D scanner system  100  is the Cyberware 3030 by Cyberware of Monterey, Calif. Other 3D scanner systems exist that scan only the face portion of the head and then construct the entire head based on the 3D data of the face. 
     Wireframe processor station  110  receives 3D range and color data  120  from 3D scanner system  100 . Wireframe processor station  110  also receives generic animation wireframe data  130 . Wireframe data  130  can be provided by any type of device, such as another processor station or a storage device, where wireframe data  130  can be stored for later retrieval. Wireframe processor station  110  can include a processor, a computer-readable memory, a first input port coupled to 3D scanner system  100 , a second input port which receives the generic animation wireframe, an output port which sends the fitted animation wireframe and a databus connecting the processor, the computer-readable memory, the first input port, the second input port and the output port. Wireframe processor station  110  can be, for example, an O 2 ™ Desktop Workstation manufactured by Silicon Graphics Computer Systems. Wireframe processor station  110  operates specialized software, including software that performs the method of the present invention whereby wireframe processor station  110  modifies generic animation wireframe data  130  with 3D range and color data  120  to produce fitted animation wireframe  140 . 
     Once wireframe processor station  110  has produced fitted animation wireframe  140 , fitted animation wireframe  140  can be used for any of the applications that otherwise support the generic animation wireframe models. Fitted animation wireframe  140  can be sent to another processor (not shown) where such applications can be executed or can be sent to storage device (not shown) for later use. 
     For convenience of notation, the Cartesian coordinate system can be used to describe the orientation of the wireframes, wireframe data, and 3D range and color data. For a front perspective of wireframe, the vertical axis can be referred to as the y-axis and the horizontal axis can be referred to as the x-axis. For a profile perspective of the wireframe where the head is facing to the left, the vertical axis again can be referred to as the y-axis and the horizontal axis can be referred to as the z-axis. Although the Cartesian coordinate system is used herein to discuss the wireframes, wireframe data and 3D range and color data, any other coordinate system, such as spherical or cylindrical coordinate systems, is also applicable. 
     Wireframe processor station  110  can include a processor, a computer readable memory, a first input port to be coupled to 3D scanner system  100  and receiving 3D range and color data  120 , a second input port receiving generic animation wireframe data  130 , an output port sending fitted animation wireframe  140  and a databus connecting the processor, the computer readable memory, the first input port, the second input port and the output port. 
     FIGS. 2A and 2B illustrate an example of generic animation wireframe  200  that can be produced from generic animation wireframe data  130 . FIG. 2A shows a front perspective of the generic animation wireframe  200 ; FIG. 2B shows a profile perspective of generic animation wireframe  200 . Generic animation wireframe  200  comprises a number of 3D data points connected to form segments of the wireframe. For example, point  210  illustrates one 3D data point connected within the wireframe; point  210  is connected to four other points and is part of four different rectangular wireframe plates. The term “plate” is used herein to refer to the area of a wireframe outlined by the segments that connect the points on the wireframe. The plates can be of any size, orientation and shape, including planar and non-planar shapes. 
     FIG. 3 illustrates an example of the generic animated wireframe with smooth shading. Smooth-shaded generic animated wireframe  300  comprises generic animated wireframe  200  where each wireframe segment is filled in with an appropriate shading color that provides a 3D perspective for the animation wireframe data. 
     FIGS. 4A and 4B illustrate an example of a display of based on measured 3D range data. FIG. 4A shows a front perspective of display  400  based on the 3D range data from 3D range and color data  120 . FIG. 4B shows a profile perspective of display  400  based on the 3D range data from 3D range and color data  120 . 
     FIGS. 5A and 5B illustrate a method for modifying the generic animation wireframe with the 3D range data according to an embodiment of the present invention. The method begins at step  500  where wireframe processor station  110  receives 3D range and color data  120  from 3D scanner system  100 . The method described in FIGS. 5A and 5B assumes that the 3D range and color data  120  provided by 3D scanner system  100  is vertically aligned with generic animation wireframe  200 . This vertical alignment can be obtained by keeping the subject to be scanned vertically aligned. 
     In step  502 , a primary point within 3D range and color data  120  is obtained. The primary point is the point within 3D range and color data  120  that can be most easily recognized automatically by wireframe processor station  110 . For example, the primary point can be the point in 3D range and color data  120  that corresponds to the nose tip of the subject. This primary point can be easily obtained automatically by wireframe processor station  110  because the tip of the subject&#39;s nose generally extends the furthest in the direction corresponding to the object&#39;s view. This primary point can also be obtained manually by an operator using an input device (not shown) connected to wireframe processor station  110 . 
     In step  504 , a vertical profile line is obtained. From the front perspective of the display of 3D range and color data  120 , the vertical profile line is drawn parallel to the y-axis through the primary point. Because 3D range and color data  120  was presumably obtained vertically aligned, the vertical profile line will run vertically along the middle of the subject&#39;s head. See for example FIGS. 6A and 6B. FIG. 6A shows a front view of display  600  of the 3D range data from 3D range and color data  120 ; FIG. 6B shows a profile view of display  600  of the 3D range data from 3D range and color data  120 . The vertical profile line is shown as line  610  and runs vertically across display  600  of 3D range and color data  120  intersecting the primary point (i.e., the tip of the nose). 
     In step  506 , secondary points corresponding to other facial features are obtained. Secondary points are points within 3D range and color data  120 , other than the primary point, that can be most easily recognized automatically by wireframe processor station  110 . Returning to FIGS. 6A and 6B, the secondary points are the points which lie along the vertical profile line  610  and are shown as lines  630 - 680 . A horizontal line  620  is also shown perpendicular to the vertical line  610  and includes the primary point or the tip of the nose. 
     Line  640  indicates the secondary point above the primary point (shown as line  620 ) which is a relative minimum with respect to the z-axis; this secondary point can be described as the location of the bridge of the nose. Line  630  indicates the secondary point above line  640  which is a relative maximum with respect to the z-axis; this secondary point can be described as the lower edge of the forehead. Line  650  indicates the secondary point which is a relative minimum with respect to the z-axis that is immediately below the primary point (shown as line  620 ); this secondary point can be described as the bottom of the nose and the upper section of the upper lip. Line  660  indicates the secondary point which is the first relative maximum with respect to the z-axis that is below the primary point (shown as line  620 ); this secondary point can be described as the furthest point of the upper lip. Line  680  indicates the secondary point which is the second relative maximum with respect to the z-axis that is below the primary point (shown as line  620 ; this secondary point can be described as the furthest point of the lower lip. Line  670  indicates the secondary point that is a relative minimum with respect to the z-axis between lines  660  and  680 ; this secondary point can be described as the mouth opening. 
     In step  508 , vertical scaling factors are determined based on the ratio of the distances between the consecutive secondary points (including the primary point) within generic animation wireframe  200  and within the 3D range data from 3D range and color data  120 . In other words, one vertical scaling factor is based on the vertical distance between lines  630  which represents the lower edge of the forehead and line  640  which represents the bridge of the nose and based on the corresponding vertical distance for generic wireframe  200 . Another vertical scaling factor is determined based on the distance between line  640 , the bridge of the nose, and line  620 , the tip of the nose, and based on the corresponding distance for generic animation wireframe  200 . The remaining vertical scaling factors are based on the distances between lines  620  and  650 , lines  650  and  660 , lines  660  and  670 , and lines  670  and  680 , and based on, respectively, the corresponding distances for generic animation wireframe  200 . 
     In step  510 , generic animation wireframe  200  is vertically scaled based on the vertical scaling factors that were calculated using 3D range and color data  120 . The points on generic animation wireframe  200  that correspond to the secondary points of 3D range and color data  120  can be previously predetermined. In other words, the tip of the nose, the bridge of the nose and the other facial features are previously determined for generic animation wireframe  200 . Alternatively, points on generic wireframe that correspond to the secondary points of 3D range and color data can be determined automatically by wireframe processor station  110  using, for example, a method similar to that described above with respect to steps  500  to  510 . 
     A horizontal slice of generic animation wireframe  200  is then vertically scaled using the vertical scaling factor that corresponds to the appropriate pair of facial features. In other words, a horizontal slice of generic animation wireframe  200  between the tip of the nose and the bridge of the nose is vertically scaled using the vertical scaling factor that is based upon the distance between lines  620  which indicates the tip of the nose in 3D range and color data  120  and line  640  which indicates the bridge of the nose in 3D range and color data  120 . Similarly, the remaining horizontal slices of generic animation wireframe  200  are vertically scaled using the appropriate vertical scaling factor. 
     In step  512 , a tertiary point is selected to define a vertical cutoff plane for the resulting vertically-scaled wireframe. This tertiary point can be selected manually by a human operator or automatically by wireframe processor station  110 . The tertiary point can be selected at approximately halfway between the profile view of the vertically-scaled wireframe along the z-axis, i.e., around the ear. Step  512  need only be performed where the application requires the front view of the fitted wireframe animation. The method illustrated in FIGS. 5A and 5B, however, can be extended to fit 3D range and color data  120  to the entire animation wireframe, including the back of animation wireframe. 
     Each point in the vertically-scaled animation wireframe is then horizontally scaled to more closely match 3D range and color data  120 . This process of horizontally scaling every point in the vertically-scaled animation wireframe is performed for each point individually until all the points in the wireframe are horizontally scaled. 
     Steps  514  to  522  illustrate a method, according to an embodiment of the present invention, by which each individual point in the wireframe can be horizontally scaled. In step  514 , a point in the vertically-scaled animation wireframe that has not already been selected for horizontal scaling is selected. In step  516 , a center point within a horizontal plane that includes the selected animation wireframe point is defined. This horizontal plane is orthogonal to the vertical cut-off plane. 
     FIG. 7 illustrates the horizontal plane within which the selected animation-wireframe point is horizontally scaled, according to an embodiment of the present invention. As shown in FIG. 7, the vertical axis corresponds to the z-axis, the horizontal axis corresponds to the x-axis, and the y-axis corresponds to an axis coming out of the page. Line  700  indicates the shape of a portion of the vertically-scaled animation wireframe. Line  710  indicates the shape of a portion of a line constructed from 3D range and color data  120 . The selected animation wireframe point is shown as point  720 . The defined center point within the horizontal plane is shown as point  730 . 
     In step  518 , a scaling line within the horizontal plane can be defined by connecting center point  730  with selected animation wireframe point  720 . The scaling line also intersects the 3D range and color data  120  represented by line  710  at point  740 . The scaling line may not intercept a 3D range and color data point represented by line  710  at exactly one measured range data point; in such a case, the coordinates of the nearest four 3D range and color data points can be averaged to give a new coordinate for point  740  which is the intersection of the scaling line with line  710 , the representation of the 3D range and color data  120 . 
     In step  520 , the animation wireframe is horizontally scaled along the scaling line. In other words, the location or coordinates of selected animation wireframe point  720  is redefined to correspond to the location or coordinates of point  740 . 
     In conditional step  522 , the animation wireframe is checked to determine whether all of the animation wireframe points have been horizontally scaled. If all the animation wireframe points have been horizontally scaled, then the method proceeds to step  524 . If all of the animation wireframe points have not been horizontally scaled, then the method continues back to step  514  where steps  514  through  522  are repeated to horizontally scale all the animation wireframe points. 
     FIG. 8 illustrates the horizontal plane within which the selected animation-wireframe point is horizontally scaled according to another embodiment of the present invention. This embodiment of the present invention can be substituted for steps  514  through  522  shown in FIG.  5 B. In this alternative embodiment, the animation wireframe is scaled proportionally to match 3D range and color data  120 . In other words, each segment of the animation wireframe between the animation wireframe points is scaled proportionally based on 3D range and color data  120 . 
     In FIG. 8, a portion of the animation wireframe is shown by line  800 . Line  810  indicates the shape of a portion of a line constructed from 3D range and color data  120 . A first scaling line connects the center point  830  with a first selected animation wireframe point  820  and an intersection point on the 3D range data at point  840  on the 3D range data line  810 . A second scaling line connects center point  830  with a second selected animation wireframe point  850  and another point  860  on the 3D range data line  810 . The point  870  indicates where animation wireframe line  800  and the 3D range data line  810  intersects the z-axis. Note that animation wireframe line  800  and the 3D range data line  810  need not intersect the z-axis at same point. Points  880  and  890  indicate where animation wireframe line  800  and the 3D range data line  810 , respectively, intersect the x-axis. 
     L W  is the length of animation wireframe line  800  between points  870  and  880 . L R  is the length of 3D range data line  810  between points  870  and  890 . L W ′ is the length of the line between points  820  and  850  along line  800 . L R ′ is the length of the line between points  840  and  860  along line  810 . The animation wireframe segment between points  820  and  850  is horizontally scaled so that L W ′/L W =L R ′/L R . This process is repeated for each segment of the animation wireframe line  800 . In this manner, the entire animation wireframe is scaled in proportion to the 3D range data; any distortions that otherwise would be present due to varying lengths of the animation wireframe segments between animation wireframe points is avoided. 
     Returning to the method described in FIGS. 5A and 5B at step  524 , once the animation wireframe has been completely scaled to match the 3D range and color data, the textural shading can be added to the fitted wireframe. Textural shading is the projection of the color imagery from the measured 3D range and color data  120  onto each plate of the fitted animation wireframe. In other words, each plate of the fitted animation wireframe is defined by the collection of fitted wireframe points and the line segments that connect these points. The color contained in the original 3D imagery for a particular group of 3D range data points is projected onto a corresponding plate on the wireframe defined by the same points. Although each plate in the fitted wireframe likely has a different shape, location and orientation than a corresponding plate that can be described by the 3D range and color data, the texture from the original image can easily be pasted onto the fitted animation wireframe because each plate in the fitted animation wireframe is defined by the points of the fitted animation wireframe. 
     Because the eyes and mouth of the fitted animation wireframe are facial objects that likely move during animation, texture shading of these facial objects should be particularly accurate. To ensure that the color imagery of 3D range and color data  120  is accurately aligned to the fitted animation wireframe, the corners of the eyes and the mouth can be aligned manually by an operator using an input device (not shown) connected to wireframe processor station  110 . An operator can manually identify alignments points corresponding to the left and right corners of each eye and the mouth within the color imagery of 3D range and color data  120 . Because the points within the fitted animation wireframe corresponding to the selected alignment points are known beforehand, wireframe processor station  110  can align the selected alignment points within the color imagery of 3D range and color data  120  with the corresponding points within the fitted animation wireframe; consequently, the color imagery of 3D range and color data  120  will be accurately aligned to the fitted animation wireframe at least in the vicinity of the eyes and the mouth. 
     FIGS. 9A and 9B illustrate the fitted animation wireframe resulting from the modification of the generic animation wireframe using the 3D range data; the fitted animation wireframe shown in FIGS. 9A and 9B does not yet have the texture added from the 3D color data. FIG. 9A shows a front perspective of fitted animation wireframe  900 . FIG. 9B shows a profile perspective of fitted animation wireframe  900 . 
     FIG. 10 illustrates an example of a fitted animation wireframe with smooth shading, in a front perspective view. The fitted animation wireframe with smooth shading is fitted animation wireframe  900 . The fitted animation wireframe with smooth shading is provide here for illustrative purposes. A fitted animation wireframe with texture shading provides a more representative animation of the subject scanned by 3D scanner system  100 . 
     FIG. 11 shows the same fitted animation wireframe with texture shading provided by the color information in measured 3D range and color data  120 , rather than with smooth shading. The resulting fitted animation wireframe with texture shading is a customized version of the generic animation wireframe based on the measured 3D range and color data  120 . Now, this fitted animation wireframe with texture shading can be used for any of the applications that support the generic animation wireframe models. 
     It should, of course, be understood that while the present invention has been described in reference to a particular system configuration and process, other systems and processes should be apparent to those of ordinary skill in the art. For example, although the present invention was described in reference to a human head, the application would be equally applicable to any sort of head such as an animal&#39;s head which possess a definable set of facial features for which a set of rules defining the secondary points can be used.