The Visible Differences Predictor: applications to global illumination problems

The Visible Differences Predictor: applications to global illumination problems
Karol Myszkowski The main goal of this Web page is to provide with more experimental results which are partially described in a manuscript entitled "The Visible Differences Predictor: applications to global illumination problems" by Karol Myszkowski (EGWR 1998). Also, the full-resolution stimuli images used in our experiments can be downloaded in a non-lossy image format. This makes possible repetition of our experiments using some different Visible Difference Predictors, or designing different experiments using our stimuli images. The organization of the experimental material presented at this Web page mostly follows that of the manuscript.

Abstract. In this study of global illumination computations, we investigate the applications of the perceptually-based Visual Difference Predictor (VDP) developed by Daly. First, we validate the performance of this predictor in shadow masking by texture and luminance contrast experiments. We also experiment with Contrast Sensitivity Functions (CSFs) derived from the results of various psychophysical experiments, various spatial frequency and orientation channel decomposition schemes, and contrast definitions, in order to check predictor integrity and sensitivity to differing models of visual mechanisms. We show applications of the VDP to monitor the perceived quality of the progressive radiosity and Monte Carlo solutions, and decide upon their stopping conditions. Also, based on the local error metric provided by the predictor we show some initial attempts to drive adaptive mesh subdivision in radiosity computations.

(A postscript version of this paper is available. Also, color figures can be downloaded.)

Daly's VDP model

Cortex transform. Visualization of the spatial frequency and orientation channels decomposition of an image processed by the amplitude-nonlinearity and CSF.
Visualization of the detection threshold elevation resulting from masking
HTML forms for experimental validation of the VDP. (A postscript version of the report on selected experiments is available. The report was published in the proceedings of Late Breaking Hot Topics at the IEEE Visualization 1998 conference.)

VDP validation experiments

Perceived shadows quality vs. masking by texture
- Texture pattern size: Tiles, Carpet1, Carpet2.
- Texture orientation
Perceived shadows quality vs. observation distance
Perceived shadows quality vs. solution convergence

VDP integrity

VDP applications

ACM TOG paper

Vladimir Volevich, Karol Myszkowski, Andrei Khodulev and Edward Kopylov; Using the Visual Differences Predictor to Improve Performance of Progressive Global Illumination Computations. ACM Transactions on Graphics 19, 2, 122-161, 2000.