When working in 3D modeling and texturing, bump maps help your 3D software to better understand the way light plays across the surface of an object. Bump maps are grayscale copies of original textures that are analyzed by your renderer specifically for the differences in height the shades of gray imply; white represents raised areas and black represents recessed areas. Converting an image into a bump map helps to make the texture more realistic.
Import the original texture image into your photo editor of choice. Adobe Photoshop, GIMP and Paint.net are excellent choices for creating bump maps.
Remove all color from the texture. You can do this by using your image editor’s desaturate function or by manually reducing the saturation with the saturation tool. Your 3D application needs a grayscale image to interpret as a bump map.
Enhance the contrast of the image with your image editor’s contrast tool. Bump maps are most easily read when there is a clear delineation between the light and dark elements of the image.
Save the bump map as a high-quality image in whatever format works best for your 3D application. It’s best to use a suffix such as “b” so you can keep your project image files sorted; for example, “treebark-N” for the normal (original) map and “treebark-B” for the bump map.
Apply the bump map to your 3D object to see how it looks. Remember, the bump map and the texture map must be identical in size for them to line up properly.
Tips & Warnings
- It’s also possible to turn images you’ve created into a bump map by following the same steps. A bump map is simply a high contrast grayscale copy of the original texture image.
- You can draw your own bump maps by starting with a black image and manually painting gray and white tones on top of it. This image will be read in the same way as any other bump map by your 3D modeling software.
- You may need to invert your bump map’s colors to create the appearance you want. If the dark areas of your normal map actually represent protrusions (dark tile with white grout, for example), inverting the colors will give the proper bump results.
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