October 2nd, 2013 at 5:00pm PDT, Agenda and Minutes
Attendees: Myeong Won Lee, Don Brutzman, Dick Puk, Joe Williams, William Glascoe
1. LOA 1, 2, 3 and H-Anim version management
- LOA 1, 2, 3 of H-Anim 1.0 :2006 should not be changed. - Enhancement should be done for future H-Anim versions.
2. BVH and X3D interpolators
Myeong Won Lee explain the difficultly of converting BVH files to X3D interpolator. Don Brutzman offered to exam the difficultly of this task. Joe thinks there is something deep (see last meeting minutes) here to discuss. Don knows little progress will come with only a BVH example. Joe explains how the task is to import Euler angles into
Intermediate conversion file X3D file BVH file
MWL tried extracting ten or so frames from BVH data but ... don't know how to translate Euler angles into 4-tuple used in X3D scene graph. Don provided references for understanding how to begin mapping BVH to H-Anim X3D encoding.
From the last agenda:
It means that X3D includes all the frames with the interpolators. It is similar to including all the BVH values per frame, but this means complex conversion to interpolators,
is very wordy, and means duplicate expressions for interpolators. In addition, in this case, interpolators becomes inappropriate terminology
because including all frames is not keyframe animation. As you know, keyframe animation means to specify only keyframes (not including all the frames).
From the keyframes, inbetweening frames should be generated automatically in a viewer, without specifying it in X3D. So, conversion from BVH to h-anim X3D using interpolators is considered inappropriate, although the conversion is possible.
Other problems: - An X3D interpolator uses one key (for example, 0.5 time during 0 to 1 time duration and one key value (for example, 1 0 0 2.5) per time, per joint, but - bvh values include three rotation values (for example, -1.249 -4.859 -3.582, z-rot, x-rot, y-rot) per joint for all frames.
This means at least three X3D interpolators are needed for one bvh rotation value at a joint, and keys and key values must be calculated for all the bvh frames depending on the frame rate of the bvh file. In addition, we do not know how to assign key time during 0 to 1 time duration for each frame.
The next two H-Anim meetings will be the 9th and 16th at the normal times.