I'm trying to figure out the size of an object in screenspace. A simple sphere at the origin using a perspective lens for the camera. I thought the following should give me the radius of the sphere in screen space (i.e. pixels):
camera.lens.getPerspective(
camera.position.distance( new Number3D())) * sphere.radius
The value is close and clearly correlates with the actual object size
but it's off by about 5%. What am I missing?
best regards,
Sören
