How can I get the word position of a point I'm seeing through a camera and on the camera's screen plane. Let's say the camera resolution is 1280x720 pixels ( 0,0 at top left and 1280,720 at bottom right), I want to know the world position of a point which will be at the pixel position of 300,200 at render output. Will this differ if I have Orthographic or Perspective camera? I think fromNDC / ptransform functions are the saviors here but I can't quite figure out how exactly. In general I'd appreciate if anyone can explain the world space, object space and camera space in Houdini in comparison which conventions that OpenGL has for instance. I read here and there that in H world space is actually camera space (or is it only in Mantra and not SOPs?). Also in OpenGL NDC is [-1,1] in all three dimensions, how is this in H? Cheers