Abstract: Non-photorealistic rendering (NPR) methods allow us to emphasize or omit detail in order to communicate information more effectively. An important issue to consider is how can we evaluate and validate the communication adequacy of these techniques? In this paper we present a methodology for quantitatively evaluating spatial perception in a functional, NPR, stereo, immersive environment. The methods described in this paper borrow from both the art and perceptual psychology communities and will provide NPR researchers with a methodology for conducting user studies to perceptually validate new rendering approaches within immersive environments.