Autodesk 12812-051462-9011 User Guide 3 - Page 2079

GIF Files GIF is an 8-bit (256-color) format developed by Informix for the CompuServe® information service. It was originally designed to minimize file transfer times over telephone lines. GIF is supported only as an input file format. You can use GIF files as general-purpose bitmaps, but you can't render to a GIF file. HDRI Files HDRI is a file format used for high-dynamic-range images. Most cameras don't have the capability to capture the dynamic range (the gamut of luminances between dark and bright regions) that is present in the real world. However, the range can be recovered by taking a series of pictures of the same subject with different exposure settings, and combining them into one image file. This type of image is called a high dynamic range image (HDRI) or radiance map. HDRI files have an .hdr extension and radiance maps have a .pic extension. The file actually contains all the data from all the pictures, so a wide luminance range is present, from bright, white highlights to the darkest black. HDR files are particularly useful as backgrounds for compositing, and as reflection maps on composited objects. When using a HDR image as a skylight, use the parameters in the Exposure group to control the brightness of the scene. Procedures To use a HDR image as a background, or as a diffuse or reflection map: 1 In the Material Editor, choose Bitmap as the map type. 2 On the Select Bitmap Image File dialog, under Files Of Type, choose Radiance Image File (HDRI). Open the HDR file you would want to use. The HDRI Load Settings dialog appears, with the image displayed in its preview window. 3 On the HDRI Load Settings dialog, look at the Measured Min/Max values to see the luminance range for the image. 4 Turn on Black Point. 7334 | Chapter 23 Managing Scenes and Projects