how to understand Camera's properties like Position, Look Direction, Up Direction?

Question

I downloaded some sample from internet. but the sharp always disappear when i changed any value of Position, or Look Direction, or Up Direction. I can't understand these properties, can anyone help me?

what's relationship between these properties? is there any sample to show these relationship?

Answer 1

Position is a vector from the scene root(origin) to the camera.

Look direction is a unary vector positioned at the camera that points in the direction the camera is looking.

Up direction is a unary vector that points to "the sky", I mean, points in the direction the camera considers as "up". Normally you use a (0,1,0) vector here.

Look here for more info.

Hope that helps.

Answer 2

Look at http://blogs.msdn.com/b/ebooth/archive/2005/12/07/500796.aspx