The traditional graphics--surface graphics only can display the surface of the 3D objects.It can not display interior properties of the 3D objects

such as texture

density field and temperature field.So many fields such as computer graphics

CAD and finite element analysis

need a new visualization technology for displaying the interior of 3D objects. The visualization technology of 3D object is an important part of a new graphics--volume graphics. Lots of information of solids

such as texture and density

are often hidden in the interior of 3D Objects. Based on the volume graphic theory and the characteristic of octree

this paper proposes a technology for interior visualization of the 3D objects for the demand of CAD system.The octree arithmetic is applied for voxlization which converts geometric objects into a set of voxels that best approximates the continuous object.As a result of uneven changes of interior properties

the technology uses the unequal voxels to best represent the details of interior properties.According to many practices

the technology not only can represent interior properties sufficiently

but also has some modeling functions.