About quaternion to euler rotation

[milkcat0904]

hello, thx for your code, i'm doing something just similar with your project. I have encountered some problems that need your help.

I have each joint quaternion and location data and i need to get the CHANNEL of BVH file. I found that the HIERARCHY of BVH file i download from website are all the same,so i just copy HIERARCHY part and write MOTION data.

I did the following things with Pyrhon: 1.calculate relative quaternion between current joint and parent joint q_relative = q_current inverse(q_parent) 2.calculate euler rotation ZXY(my BVH file all the CHANNEL is Z-X-Y rotation) ''' y1 = 2(orientationXorientationY - orientationWorientationZ) y2 = orientationWorientationW - orientationXorientationX + orientationY+orientationY - orientationZ*orientationZ

x = 2*(orientationY*orientationZ + orientationW*orientationX)
x = +1 if x > +1 else x
x = -1 if x < -1 else x

z1 = 2*(orientationX*orientationZ - orientationW*orientationY)
z2 = orientationW*orientationW - orientationX*orientationX - orientationY+orientationY + orientationZ*orientationZ

rotationZ = math.degrees(math.atan2(z1, z2))
rotationX = math.degrees(math.asin(x))
rotationY = math.degrees(math.atan2(y1, y2))

euler_rotation = [rotationZ, rotationX, rotationY]

'''

After the visualization, the movement is wrong. This problem has been bothering me for a long time, I need your help.

[meshonline]

Hi,

I’m not familiar with Python, so I can not help with your question.

Art

在 2018年8月13日，下午3:51，catidog notifications@github.com 写道：

hello, thx for your code, i'm doing something just similar with your project. I have encountered some problems that need your help.

I have each joint quaternion and location data and i need to get the CHANNEL of BVH file. I found that the HIERARCHY of BVH file i download from website are all the same,so i just copy HIERARCHY part and write MOTION data.

I did the following things with Pyrhon: 1.calculate relative quaternion between current joint and parent joint q_relative = q_current inverse(q_parent) 2.calculate euler rotation ZXY(my BVH file all the CHANNEL is Z-X-Y rotation) ''' y1 = 2(orientationXorientationY - orientationWorientationZ) y2 = orientationWorientationW - orientationXorientationX + orientationY+orientationY - orientationZ*orientationZ

x = 2(orientationYorientationZ + orientationW*orientationX) x = +1 if x > +1 else x x = -1 if x < -1 else x

z1 = 2(orientationXorientationZ - orientationWorientationY) z2 = orientationWorientationW - orientationXorientationX - orientationY+orientationY + orientationZorientationZ

rotationZ = math.degrees(math.atan2(z1, z2)) rotationX = math.degrees(math.asin(x)) rotationY = math.degrees(math.atan2(y1, y2))

euler_rotation = [rotationZ, rotationX, rotationY] '''

After the visualization, the movement is wrong. This problem has been bothering me for a long time, I need your help.

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[c4b4d4]

Hi, did you manage to solve this?

[meshonline]

I just realized that you can read the source code of the BVH importer of Blender, if you have confirmed that your code is right, there is another thing you may forget to setup, you need to setup the rotation mode for each joint from 'Quaternion(WXYZ)' to 'ZXY Euler’ in pose mode.

在 2019年1月23日，上午12:44，Carlos Cabada notifications@github.com 写道：

Hi, did you manage to solve this?

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[c4b4d4]

I need to do everything in real-time, not over recorded files. I'm doing a virtual character control but the rotations seem to be so wrongly done.

This is what I'm facing: Stack Overflow Question