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meshonline / kinect-openni-bvh-saver

This project is based on OpenNI2, NITE2, and OpenCV2, it will automatically save many skeleton animation clips to bvh files.
MIT License
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Stereo Camera application #9

Open Jack-No1 opened 2 years ago

Jack-No1 commented 2 years ago

Hi, i'm implementing this code in my project where i need to obtain the quaternion value for each joint, i 'm using stereo vision to obtaining the 3d points of each joints. so my question, is this also working for camera sensor or is there could be a difference of kinect although i got the reconstructed coordonates. sorry for the question cause i don't have a deep knowledge about the quaterneon so i'm still learning.

meshonline commented 2 years ago

'kinectbvh.h' use the functions in 'vet_math.h' to build quaternion from scratch.

m = mat3_from_axis(vx, vy, vz); q = quat_from_mat3(m);

The first line build a matrix from two major axis(vx, vy, vz), where vz is a zero vector. The second line build quaternion from the matrix.

Jack-No1 commented 2 years ago

in function GetEulers in kinectbvh.h , why inverting the quaternion parent Joint and what is the function "quat_left_multiply( ...)" ; i am stuck here.

meshonline commented 2 years ago

In vector multiply operation, left multiply means that you multiply the left vector with the right vector. For example: left_multiply(a, b) = b * a We invert the parent and multiply the child to get the relative value (local value).

xorespesp commented 1 year ago

The first line build a matrix from two major axis(vx, vy, vz), where vz is a zero vector. The second line build quaternion from the matrix.

Does "matrix" in the sentence above mean a rotation matrix?

I'm currently struggling to understand the part that creates these "matrices" for each joint.. (in function CreateQuaternionInformation in kinectbvh.h)

Thanks

meshonline commented 1 year ago

Yes, "matrix" mean a rotation matrix.