May 7, 2009

World Building With 3D Paint and Projected Paint

Exploring methods of world building for computer animation has been my primary focus this semester. As a group, we decided that some goals for a successful world included evidence of a past and history. The created world must also be cohesive within itself. Each world has its own set of guidelines to follow, whether it is color scheme, physics of motion, or something else. All of these components help to make a world believable.

Our intentions as a class were to find a way to create this world quickly and easily but still with a high quality result. We decided that painting was the best way to do this. Skilled painters can create compelling and detailed scenes very quickly, so we began be exploring how to integrate traditional painting with a computerized 3D world.

Using Maya's 3D paint proved to be a good way to paint a layout on a character or object, but did not allow for much detail when painting, as the paint tool was fairly simple. Issues arose when areas of the mesh met, and painting straight lines accurately was extremely challenging. 3D paint offered a lot of exciting options such as painting transparency, luminance, or even displacement, but since each property needed to painted over again from scratch is was a difficult process and not as intuitive as "real" painting.

After a suggestion from Jeremy, we began to explore camera projections as a source of paint. I worked on creating a shader that would project a painting drawn in photoshop onto objects within the scene. The painting would be based off of a rendered frame and then taken back into Maya.

At first I was creating shaders that preserved the original 3D paint, which also allowed for a method in which the painter could use both 3D paint and then a projection for more detail. This involved a layered shader, and after some trial and error we successfully created a shader the preserved both paint layers as well as the transparencies between them so that they overlapped correctly.

An early problem with projected paint that caught light was that paint did not translate well between objects. Our example was that grass painted on the ground that overlapped a booth received light at different angles and the scene instantly revealed that the grass was painted on. To avoid this problem we began painting light and shading into the painting and having 3D lights not affect the object's texture. Another issue with projected paint was that paint did not stick to moving objects. This was easily solved by using texture reference objects, which "glues" the paint on at a specific frame.

As the semester advanced, there was a clear continual shift towards "true" painting with shading, lighting, color, texture, and even shape information all within the painting itself. We moved from 3D painting to projected paint that was lit with lights in Maya, to painting the light on surface shaders which would catch no light at all from Maya. I think this is a result of painting traditionally being easy, intuitive, and fast - especially for a professional painter.

For a short while I explored the use of a quad shading switch. Since each object needed a separate shader with only slight differences from each other (different layers within the same PSD file) it seemed logical to use a quad switch so that all of the objects utilizing the same PSD file could use the same texture. This seemed to be a brilliant plan until it was discovered that linking objects to PSD layers with the switch was time-consuming and confusing at times, especially with texture references were being used. Perhaps using individual shader materials for each object or one material with a shader switch is a decision the individual painter should make, as everyone works differently, and some might find one way easier than the other.

I think projecting a complete painting is a great way to make a computer generated world look believable. With a talented painter, I think there are endless possibilities to making a scene detailed and compelling in a short amount of time. Based on my own skills at painting, I think I preferred when Maya took my painting and handled the perspective and lighting for me. However, this method has some obvious weaknesses, including not knowing how your paint will look once in Maya, and the issue with the grass. I imagine that in a professional setting a painter would feel more comfortable painting the light in, in which case they can use the latter method of surface shaders which proved to be successful. All new techniques and methods take time to get used to, but I feel that projecting paint from photoshop in this way could speed up the entire process once it becomes familiar.

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