Dimensions and Models of Viewing Space for Computing Aspect Graph

The establishment of dimensions and models of viewing space is quite important for computing aspect graph in computer vision.On the basis of the equivalent structure of the line drawing for computing aspect graph,it is shown that the dimension of viewing space is two dimensional space under orthographic projection and three dimensional space under perspective projection.Mean while,the method for establishing the model of viewing space is given,which makes the problem for computing aspect graph of objects simple.