Ernest Burden III Posted November 18, 2006 Share Posted November 18, 2006 Something I've often used in my CG rendering is the classic watercolor technique called underpainting, where you paint a color wash on your paper before putting on any other paint. The tones read through transparent WC washes and provide a nice sense of unity to the rendering. The same can be done in CG by putting a colorfade OVER your picture in linearburn mode, set to a very low strength, like 5% - 20% depending on taste. This has the effect of darkening the picture which is both desirable and a bad side-effect. By using a copy of the colorwash layer set to 'color' mode and a very small strength, you can pull the tones without darkening. It is a technique based on the picture being a 2D image. Remember--renderings are not 3D environments anymore. They are pictures, and must work as pictures. Here's a color wash I used on an aerial exterior, but seen by itself at 100%: You can do something similar in 3D, and that's what I'm writing about. When you have a scene, either interior or exterior, and you know how you want to show it, you have the opportunity to think about what areas will be darker, bluer, warmer. This should be part of your overall planning. Sure CG software can do near-perfect photorealism with everything everywhere the perfect tone. But that's so boring. Colors change with distance and color carries emotional cues. Use them to your artistic advantage. Color is fun. Putting an underpainting in 3D is done by using lights that don't cast shadows. Put a color gradient in the falloff of a light, set it to not cast shadows and you're on your way. You will want to experiment with both diffuse and ambient-only lights to see what you like. Start with high-strength to see the effect, then tone it way down to just add that bit of extra life. If you want to push back the far corner of a room, shine some deep blue-purple on it, while the center of the room gets a near-white (no added color) fading into some yellows to warm up near-ground. I will put a light above a scene, often another shining up from beneath. One set to ambient (adds color without any gourand-like shading--like a flat wash) and the other to diffuse to begin to define some shapes within the colors. Both set to low strength. Here's a project I just handed in, its a bar in Florida. These first images show preliminaries with no lighting but the color washes. I kept them to the end, but once the actual lighting is in, its not so noticeable. The client wanted to show a 'low-light' setting, and I was determined to not lose color in the darkness. The whole place was black and dark materials, with brown-glass mirrors and panels of shiny metals arranged in random rectangles. Another advantage to this was having even my early images to the client have the 'feel' I wanted rather than a bland gourand screengrab. Another idea for bringing in color in 3D is to use an ambient occlusion shader set to a gradient and a very wide effect so that tight corners are dark cools, then ramps to light warms. It looks great, even for a simple, early model before you have ANY actual lighting in place. Link to comment Share on other sites More sharing options...
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