What is the Difference Between Image Space and Object Space?

The difference between image space and object space lies in their representation and application in computer graphics and optics.

Object Space:

• Object space refers to the 3-dimensional space in which a graphic object is defined.
• In optics, object space is the space between the source and the optical system.
• Object space contains the rays coming from the object, not affected by the lens.
• Object-space methods are generally used in line-display algorithms.

Image Space:

• Image space is the projection of the object defined in 3D to two-dimensional screen space.
• In optics, image space refers to the space between the optical system and the observer.
• Image space can contain real image points behind the system and virtual image points before it.
• Image-space methods are implemented in the screen coordinate system, and visibility is decided point by point at each pixel position on the view plane.

In summary, object space represents the 3D definition of a graphic object, while image space is the 2D projection of that object on a screen. Object-space methods are more line-based, whereas image-space methods are more surface-based.

Comparative Table: Image Space vs Object Space

The main difference between image space and object space lies in their representation of geometric properties in computer graphics. Here is a table comparing the two:

In summary, object space deals with the 3D geometric properties of an object before any transformations, while image space deals with the 2D representation of objects after transformations and focuses on the geometric relations among objects in the scene. Image space methods are more computationally intensive, as they determine the visibility of each object surface.