Compute camera locaitons and euler rotations on spehere of center C and radius R

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1

Hello,

I would like to compute a list of random camera positions and corresponding euler rotations on the sphere where at each locations, the camera should be pointing to the object in the center.

I would like to do it blender-python script.

Any help is appreaciated?

Thanks

2

Welcome to the board. Do note that these sorts of general math utility questions are better served at Blender Stack Exchange. Higher traffic, more eyeballs, oriented more toward general questions - and many developers here answer there as well. This is a site about specifics of the Blender API. I see that you did post at BSE (how to get camera locations and euler rotations for 3d points hemisphere surface?). I suggest that you consider it your main go-to site for broad-topic Blender python questions.

That said, the approach I fancy is based on Vector.to_track_quat('track', 'up') (See: to_track_quat()) Use it to orient an object to an arbitrary axis. See also: Align Object to Vector using python.

# Create a camera and Empty by whatever means that suits.
# Choose a radius to suit
RADIUS = 15 
# Translate matrix along +Z
xlate = Matrix()
xlate[2][3] = RADIUS
# Camera to position on the hemisphere.
cam   = D.objects['Camera']
# Not needed for solution - Just visualizes target
empty = D.objects['Empty']
# randomly choose some orientation; scale to radius
v0 = RADIUS * noise.random_unit_vector()
# Fetch tracking quaternion to align camera to orientation
quat0 = v0.to_track_quat('Z', 'Y')
# Translate camera length of radius, orient camera with tracking quad
cam.matrix_world = quat0.to_matrix().to_4x4() @ xlate

v0 is an arbitrarily oriented sphere radius. By ‘sphere radius’, I mean an axis where I arbitrarily choose one endpoint on the surface of the sphere (RADIUS * noise.random_unit_vector()) and the other endpoint is assumed to be at the center of the sphere ((0, 0, 0)). Generate as many as these to suit; the example just illustrates one sample. For each radius, invoke its to_track_quat() to get a quaternion to align the camera to the radius. The 'Z', 'Y' parameters are so chosen to point the camera in the +Z axis direction, toward the center, and orient the top of the camera in the +Y direction. Compose with a translation matrix to move the camera from the center of the sphere to the surface of the sphere. See screenshots.
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or_01

Have fun!

3

Thank you! This helps!