Found what I was looking for in the Renderman documentation (all rights reserved), though it applies to Poser only peripherally since it doesn't have mip-map capabilities: "Textures are indexed using (s,t) coordinates ranging from 0 to 1. Note that the coordinates of a texture map are like the coordinates of a raster image: the pixel with texture coordinates (0,0) is at the upper left corner of the image. The s coordinate increases to the right and the t coordinate increases from top to bottom. For reasons internal to the texture mapping software, texture files must be an even power of two in width and height. Any input image which is not already a power of two in both dimensions will be resized, as described below. For shadow textures, the resolution of the texture file is derived from the height and width of the image file, each rounded up to the next larger power of two. For example, a 256×512 image file will generate a 256×512 texture, while a 250×84 image file will generate a 256×128 texture. Additional black (zero) pixels are added to the picture data as necessary to fill the texture file. The shadow operation may be incorrect for input images that are not sized to powers of two. For simple textures or environment textures the resolution of the texture file is determined from the height and width of the image file and the operation specified by the -resize option. If either the width or the height of the image is an exact power of two, that dimension is left unchanged. Any dimension that is not an exact power of two will be adjusted according to the -resize operation. The resize operation may be one of: [the following options, which I have omitted] The default resize operation is up. When texture access corrects for the resize operation, as in up, down and round, the texture coordinates are 0 to 1 across the longest dimension and adjusted by the image aspect ratio across the shorter dimension so that image pixels will remain square if texture mapped onto a square patch." I believe this excerpt supports the power of two link that I quoted in post #22.