Coordinate transformation or spatial transformation, essentially a change in relative coordinates, absolute coordinates unchanged.
There are two world-space objects A, B. A conversion to the B coordinate space means: A transformed from the local coordinate space to world space B, i.e. A repositioning coordinates in the local coordinate system B (A is determined in the coordinate system B relative coordinates)
Approach is very simple:
1, BA obtain a vector V,
2, decomposed into the V of the respective local coordinate axes B
The result is the coordinates in the local coordinate system A in B, the object A will transform the local coordinate system to the object B, referred to as A conversion to the space B.
In the most commonly used game engine developed several transformation:
1, the rendering pipeline for rendering an object, the object is transformed to camera space
2, rendering a shadow map shadow map, the camera will be transformed into light space