Color and texture

Artists use color, intensity, and texture to draw attention to specific areas of an image. Texture use is particularly interesting because it is common for texture to be elided (or simplified) depending upon the viewpoint, projected size, and the importance of the object.

I have developed two systems for allowing the user to paint view-dependent texture directly on the model. Both of these systems allow the user to pick particular viewpoints and projection image-sizes, then paint onto the model. When the object is rendered, the system blends between the appropriate texture maps. Sort of Mip-mapping on steroids.

The primary difference between the two systems is how the texture maps are created. In the first, the object is already parameterized. In the second, the projected object itself serves as a texture map parameterization. This involves some cleverness with the depth map in areas of occlusion.

We have also automated this process, to some extent, by letting the user choose both a texture and color for lighting the object. This is a generalization of the Gooch warm-cool rendering, extended to textures. The challenge here is how to smoothly change between textures, both from shadowed to lit areas and as the object moves. This paper presents both object-based (a-la the previous papers) and image-based approaches.

Artists often combine abstraction with realism when rendering objects with a lot of detail, such as trees. They outline the basic shape of the tree with a shaded blob, then introduce detail where needed to create the illusion of detail everywhere. This paper is a semi-automated approach of this flavor - the user still has a great deal of control over the degree of abstraction versus realism, and other rendering attributes.

Photographers spend a great deal of time and effort creating good lighting, especially for objects that have concavities and various material types. In this paper, we capture the object under many different lights, then employ a painting approach to re-light the object the way we want. Joint work with Jack Tumblin and Bobby Bodenheimer.

We are continuing to look into the questions of image-editing based on the human visual system.

Papers

• Lighting real-world objects using a painting interface.
• Composition. Each object in the scene has its own camera, color and light control.
• Shading using both texture and color.
• View-independent texture maps. This is the first draft of the following paper, which operated on manifold surfaces. Essentially, each "texture" map was actually a set of texture maps parameterized by both view direction and object distance. (unpublished)
• A longer version of the above paper. (unpublished)
• Painting view-dependent texture maps. The painted images themselves are used as texture maps, with the camera projection creating the texture coordinates. (unpublished)
• Painting view-dependent textures, combines the above papers.
• Combining abstraction with realism, in this case, to render trees.
• View-dependent graftel textures. (unpublished)
• Color study to determine the effects of warm/cool colors on depth.
• Perceptually meaningful depth editing. Combines the color depth study with using spatial imprecision to give an illusion of motion.

Movies

• Sequence with no non-linear effects (OpenGL)
• Sequence with no non-linear effects (Radiance)
• Sequence with non-linear and color effects (OpenGL)
• Sequence with non-linear and color effects (Radiance)
• Rendering trees in a combination of abstraction and realism.
• Rendering trees with transparency.
• Rendering trees with slightly less transparency.
• Dark red texture applied to a model (3D texture painting).
• Dark red texture applied to a model (synthesized texture).
• Dark red texture applied to a model (view-dependent painting).
• Dark red texture applied to a model (Object-based).

Students

• Reynold Bailey (PhD)
• Ankit Mohan (PhD, Northwestern University)
• James Tucek (BS/MS)
• Nathan Dudley (MS)
• Ashish Khatri (undergrad)
• Michael Kowalski
• Christopher Kulla (undergraduate, Sunflow)