Bump Texture Tools
Frequently Asked Questions

1. What are Bump Texture Tools?
2. What is Shape from Shading?
3. What is a height map?
4. What is Bump Removal?
5. What are the requirements?
6. What are the tool's limitations?
7. What is bump mapping?
8. Why not paint a bumpy look into the texture?
9. Who would use bump mapping?
10. What objects make good candidates?
11. Why remove shading?
12. Are there other uses for height maps?


 

What are Bump Texture Tools?

Bump Texture Tools allows users to add bump and displacement textures to imagery, making it more realistic. Bump Texture Tools consists of two software plug-ins for Adobe Photoshop™, Shape from Shading and Bump Removal.

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What is Shape from Shading?

Shape from Shading facilitates making bump textures (maps) from at least one, two or three image sources. If more than one image is used, only the light angle can change. The user then indicates the angle of the light for each image, and the Shape from Shading plug-in will calculate a bump texture (height map) for the image.

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What is a height map?

A height map is a typically 8 bit bitmap that indicates the height of a surface above plane. In the case of Shape from Shading, the plug-in stores the Height Map in the fourth bitmap channel of a 24 bit color image. The height map is presented as a gray scale image where luminance represents height. A byte value of 0 is the lowest point, while 255 is the highest.

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What is Bump removal?

The Bump Removal plug-in does the opposite of Shape from Shading. A 24 bit image that has shading to do height variations is brought into the Bump removal plug-in. From the corresponding height map, the algorithm removes shaded areas, rendering the image with a flat look with just color information.

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What are the requirements?

Windows 95, 98, ME, Windows NT 4.0 or Windows 2000 - Adobe Photoshop™ 4.0 or higher for the PC.

 

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What are the tool's limitations?

The Shape from Shading plug-in works best if there aren't any shadows and the color of the surface is uniform in the source images. The same is true for Bump removal. If colors vary, Shape from Shading will be unable to accurately calculate the height map. But if 3 images are available, Shape from Shading can handle varying colors. The plug-ins often work well with source images that are less than ideal, but not always.

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What is bump mapping?

Bump mapping is an additional channel (height map) provided to an image generator or rendering engine which gives the object an appearance of a bumpy surface as the shading changes with illumination changes. Higher luminance variation will increase the effect. However, bump maps have no effect on the shape of the geometry. Some 3D rendering applications, such as 3D Studio Max, can change geometry with displacement maps, and our tools support displacement mapping as well.

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Why not paint a bumpy look into the Texture Map?

That can be done if you're creating a still photo that will always be viewed from the same angle. However, as the viewpoint and light source positions change, it will become evident that the object is merely painted, similar to a mural. In the real world, the appearance of a bumpy surface changes relative to the light and viewing position.

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Who would use bump mapping?

Bump mapping has a variety of uses, from rendering engines to real-time applications. In real-time and gaming, it's always been necessary to keep polygon budgets at a minimum, while achieving a rich detailed look. With graphic card technologies improving, it's becoming possible for game developers to implement bump mapping for more realistic environments. Military VR applications can include bumps on water or terrain in low flying scenarios to give the viewer an increased sense of depth.

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What objects make good candidates?

Just about any real world surface object contains some degree of bumps. Usually natural objects, such as wood, rock or water make good bumpy surfaces.

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Why remove shading?

To make the Bump Texture Tools work best, the Diffuse or color map should only provide color information. As the light and viewing angle changes, so will the appearance of shaded areas. Bump Removal will strip shading from the color map, allowing the image generator/rendering engine to provide colors needed to give the appearance of a bumpy surface relative to the light source.

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Are there other uses for height maps?

Height maps that define bumps are a good start to achieve realism. But most commercial 3D applications today have many attributes that allow artists more control of material properties. These may include the levels of glossiness, specular light, displacement, etc. Most real surfaces are not even in appearance. For example, some metals have spotted areas of high gloss, depending on corrosion and exposure to oil and environment. Fortunately, these attributes can be defined with 8 bit maps which determine the amount of effect that will occur. These subtle differences can help a material appear more photo-realistic when rendered. When preparing a bump map, one must keep in mind that a luminance value of 0 has no effect, while a value of 255 is 100%. It's also a good idea to get into the habit of observing different objects within your surroundings. You want to study their imperfections, color variation and how the surfaces react to the light. Ask yourself how you can achieve the same effect with the tools provided in the material editor of your 3D application.

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Copyright CGSD Corp. 2001