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..::pearlescant spray paint::..

Spray paint is adhered to car surfaces in a two stage operation. The base coat consists of the paint colour or effect and the second the lacquer or wax surface to protect the paint and make it. By looking at real world examples, such as various car surfaces we can note how the surface reacts to it’s environment and to light. The light produces two hilights – a large faint hilight where the light hits the paint layer, and a small intense hilight where it hits the lacquered surface.

Creating this effect in 3ds max is quite simple; it comes with a Multi-Layer material to generate such effects, so creating simple coloured spray-paint effects is quite easy; a colour choice, the amendment of both hilights to emulate the two hilights for the paint and lacquer layers, and the addition of a Raytrace map in the reflection slot. By observing real world examples again, you should note that the reflection in a car is slight when viewed full on, but more intense at the perpendicular.

Therefore, the Raytrace map should be masked (or mixed) with a Falloff map set to Perpendicular / Parallel, with the Raytrace map being located in the Side slot.

If we observe a pearlescent-painted car, or other object with similar properties, such as a shell or ornament, we can observe that the pearlescent effect only appears on the perpendicular and when light is shining on it. Also, if the object is rotated, we will note that any colours that appear are normally distortions of the reflected image and will stay in the same place when the object is rotated back to the same place. Breaking this down, we need to re-design our spray paint material in such a fashion.

Now the base coat is metallic, it should be created as such. A metal material should be created to emulate this, with the base colour chosen in the Diffuse colour slot as before. As the base coat to these types of paints is slightly rough, a noise bump map should be created. The falloff colours can be whatever your choosing; from greens to purples, reds to yellows, it all depends on your preference. To create these, create a Falloff map set to Perpendicular / Parallel with another Falloff map in the Side slot, set to Shadow/Light. This will prevent any reflections being emitted from non-lit areas. Create a Gradient Ramp material in the Light slot and set the Gradient Type to Normal to change colour on the object’s perpendicular. Composite this material with a copy of the original spray paint material that has been set to 0% opacity and the Falloff & Raytrace map reflections remaining intact.

This gives us our lacquer reflections and base coat reflections also. You may wish to amend the position of the Gradient Ramp material to the Specular Color of a single Multi-Layer material and play with the settings. Also, don’t forget to have a go at amending the Falloff and Anti-Aliasing parameters (after turning Global Anti-Aliasing on) to create blur effects depending on distance to add more realism to the lacquer’s reflections.

Enlarge ScreenshotThe core components of the pearlescent material. These are composited together using either a Composite or Shellac materials
Enlarge ScreenshotA simple scene displaying the material reacting to light. Note the reflections fall off to the center as with the pearlescent effect yet still reflect in the other spray painted objects
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Due to the amount of anti-aliasing in the Raytrace maps (and the composite material), the resulting render may take a long time to complete. To rectify this problem, turn off anti-aliasing in the Raytrace map's anti-aliasing parameters, and turn on supersampling. Supersampling will smooth out any jagged aliased reflections but will sacrifice any blurring of reflections. To speed up the render further, turn supersampling off.

Initially published: 3D World magazine, Issue 23, March 2002.

Copyright © Pete Draper, March 2002. Reproduction without permission prohibited.

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