MANAGING LEVEL OF DETAIL IN VIRTUAL ENVIRONMENTS - A PERCEPTUAL FRAMEWORK

In the companion paper, Watson et al. (1997), we demonstrated the effe ctiveness of using perceptual criteria to select the amount of detail that is displayed in an immersive virtual reality (VR) system. Based u pon this determination, we will now attempt to develop a principled, p erceptually oriented framework to automatically select the appropriate level of detail !LOD for each object in a scene, taking into consider ation the limitations of the human visual system. We apply knowledge a nd theories from the domain of visual perception to the field of VR th us optimizing the visual information presented to the user based upon solid metrics of human vision. Through a series of contrast grating ex periments, a user's visual acuity may be assessed in terms of spatial frequency (c/deg) and contrast. The results of these tests can be mode led mathematically using a contrast sensitivity function (CSF). Theref ore, we can use the CSF results to estimate how much visual detail the user can perceive in an object at any instant Then, if we could descr ibe this object in terms of its spatial frequencies, this would enable us to select the lowest LOD available without the user being able to perceive any visual change.