Vray Overbright Error: One specific cause verified

[Tim Fairbanks]

I'm just posting this as a technote for anyone who might be doing a forum search on the pervasive Vray "overbright or invalid color" error.

 

The attached screencaps show the 3dsmax material Editor settings that relate to this problem.

 

One specific, verified cause of the error is Standard 3dsmax materials with bitmaps that have had the RGB Offest in the Output section of the bitmap parameters adjusted to anything less than 1 (e.g. -0.1 see attached image #1)

 

Vray does not return an error with Standard Materials when the "Enable Color Map" function curve is used instead of RGB Offset to reduce the brightness of a bitmap (see attached image #2). Note that the value of the image brightness using this method is 0.9 rather than -0.1 using the RGB Offset. It appears that using a negative number in the RGB Offset is an integer operation, which creates a conflict with Vray's floating point mathematics.

 

CORRECTION: Using any negative value in the Function Curve will also return an error (e.g. by reducing the value of either of the function curve handles below zero).

 

This error also does not ocurr with Vray Materials, which substantiates the common wisdom that Vray Materials should always (if possible) be used with Vray.

 

 

 

TimF

Edited February 23, 2009 by TimF
Corrected/added info re: Function Curve