Verification of computer vision theories is facilitated by the development and implementation of computer simulation systems. Computer simulation avoids the necessity of building actual camera systems; they are fast, flexible, and can be easily duplicated for use by others. In our previous work, we proposed a useful computational model to explore the image sensing process. This model decouples the photometric information and the geometric information of objects in the scene. In this paper, we further extend the proposed image sensing model to simulate the image formation of moving objects (motion) and stereo vision system. The simulation algorithms for curved objects, moving objects, and stereo imaging are presented. Based on the proposed model and algorithms, a computer simulation system called Active Vision Simulator (AVS) has been implemented. AVS can be used to simulate image formation process in a monocular (MONO mode) or binocular (STEREO mode) camera system to synthesize the images. It is useful for research on image restoration, motion analysis, depth from defocus, and algorithms for solving the correspondence problem in stereo vision. The implementation of AVS is efficient, modular, extensible, and user-friendly.