Systems and methods for capturing motion in three-dimensional space
View Patent ↗Methods and systems for capturing motion and/or determining the shapes and positions of one or more objects in 3D space utilize cross-sections thereof. In various embodiments, images of the cross-sections are captured using a camera based on reflections therefrom or shadows cast thereby.
1. A method of locating a control object appendage in three dimensional (3D) space, including:
recording images of a control object appendage in 3D space using at least two geometrically distinct predetermined vantages;
calculating by a processor four co-planar tangents to observed edges of the control object appendage from the recorded images;
fitting an ellipse by a processor to the cross-section of the control object appendage by selecting the ellipse from a family of ellipses that fit the four co-planar tangents using an assumed parameter;
repeatedly fitting contiguous cross-sections to the control object appendage; and
constructing the control object appendage in 3D space from the contiguous cross-sections.
2. The method of claim 1 , further including substituting one or more fitted parameters of a first fitted ellipse for one or more of the four co-planar tangents and the assumed parameter when fitting an adjacent second ellipse.
3. A method of locating a complex control object in 3D space, including:
for a complex control object model that includes a palm and multiple fingers, applying the method of claim 2 to construct the multiple fingers of control object appendages; and
fitting cross sections of a palm to observed edges from the images in positions correlated with the multiple fingers.
4. The method of claim 1 , further including using a first fitted ellipse to filter fits of additional ellipses to the contiguous cross-sections.
5. A method of tracking motion of a complex control object in 3D space, including:
repeatedly applying the method of claim 4 over time; and
calculating motion of the complex control object over time based on differences between modeled locations of the complex control object over time.
6. A method of tracking motion of a control object appendage in 3D space, including:
repeatedly applying the method of claim 1 over time; and
calculating motion of the control object appendage over time based on differences between modeled locations of the control object appendage over time.
7. The method of claim 1 , further including:
determining that only three co-planar tangents are available in portions of the recorded images and fitting a circle instead of an ellipse for the portions of the recorded images, including:
calculating by a processor the three co-planar tangents to observed edges of the control object appendage from the recorded images; and
fitting a circle by a processor to the cross-section of the control object appendage using at least the three co planar tangents.
8. A method of locating a complex control object in 3D space, including:
for a complex control object model that includes a palm and multiple fingers, applying the method of claim 7 to construct the multiple fingers of control object appendages; and
fitting cross sections of a palm to observed edges from the images in positions correlated with the multiple fingers.
9. A method of tracking motion of a complex control object in 3D space, including:
repeatedly applying the method of claim 8 over time; and
calculating motion of the complex control object over time based on differences between modeled locations of the complex control object over time.
10. A method of tracking motion of a control object appendage in 3D space, including:
repeatedly applying the method of claim 7 over time; and
calculating motion of the control object appendage over time based on differences between modeled locations of the control object appendage over time.