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..::chalk line material::..

Enlarge Screenshot The trick to this effect is to get the chalk lines to break up as illustrated in this image. Note how they are fractured based on several properties: firstly the width and/or curvature of the chalk itself, secondly dust effect creating a diffused particular effect, and thirdly the raised brush lines of the board itself. Each of these elements must be created in turn for the effect to be believable…
Enlarge Screenshot … Thankfully, the Ink n Paint material allows you to do this. You don’t need the interior of the object to be shaded (unless you want a kind of smudged chalk effect which you could set up later with a blurred version of the line map setup) so this can be disabled. The chalk dust effect is set up with a simple black & white Splat map assigned to the Ink section of the material, instanced in its Width, Outline, Underlap & SMGroup slots.
Enlarge Screenshot This helps vary the line width depending on map intensity coupled with a low Ink quality adds some natural variation. The brush line removal is produced with a desaturated Gradient Ramp map (using an RGB Tint map as you only want it to be black & white) with a bitmap loaded into its gradient for a random result as a sub-map within the Splat map. The end result is effective yet should be tweaked (eg line Width parameters) depending on the scale of your own scene.
Download the max file! Zip file to accompany.

..::quick tip::..

To add to the effect, try using an instanced version of the Brushstrokes gradient to drive a Mix map, assigned to the environment background as illustrated in the finished 3ds max scene.

Initially published: 3D World magazine, Issue 94, September 2007.

Copyright Pete Draper, September 2007. Reproduction without permission prohibited.