All textures in Shockwave 3D must be power of 2 (e.g. 32, 64, 128, 256, 512, 1024) in dimension. This is in common with many graphics cards.
If you use non-power-of-2 textures, Director has to resize them before they can be displayed.
I suspect the resize method is nearest neighbor, which is probably why your texture appears slightly blurred.