This attribute tells V-Ray that the texture may contain negative colors. Normally V-Ray clips negative texture values as they are invalid for most shading operations. However in some cases (e.g. for displacement), negative values are useful. Note that you can also control negative shader colors globally from the Materials section of the Overrides tab in the V-Ray settings. It can be added to File and Substance textures.
Allow negative colors – When enabled, V-Ray does not clip the texture values.
and Substance textures to control their filtering.
Column
width
62%
Override Texture Filter – Override the default texture filter that V-Ray chooses based on the Maya attributes of the particular texture node. For more details, please see the V-Ray Filter Interpretationtable below.
Texture Filter – The V-Ray internal texture filter.
Nearest – The nearest texel from the map is taken, without any interpolation. Smooth – The colors are computed with bilinear interpolation from the texels. Smooth with mipmaps – Pyramidal MIP map filtering is used to compute the texture color. SAT – A summed area table is used to compute the texture color. Elliptical – High quality anisotropic MIP map texture filtering that reduces blurring and aliasing artifacts.
Smooth Method – The V-Ray internal texture smooth method.
Bilinear – The image values are interpolated from four pixels in the bitmap. This is the fastest interpolation method, but the result is not continuous (non-smooth) and may produce artifacts when the map is used for displacement or bump mapping. Bicubic – The image values are interpolated from sixteen pixels in the bitmap. This is the slowest method, but the results are smooth without too much blur. Biquadratic – The image values are interpolated from nine pixels in the bitmap. This method is faster than the Bicubic interpolation, but may smooth the image too much.
For example, if a File node is used and Override Texture Filter is off or not added, V-Ray looks at the Maya Filter Type attribute. Here's how V-Ray translates the Maya filters to V-Ray filters:
Maya Filter Type
V-Ray Filter
Support for tiled images
Off
Smooth
Uses tiles only from the largest mipmap level
Mipmap, Box, Quadratic
Smooth with mipmaps
Supports tiled mipmapped images
Quartic, Gaussian
SAT
Loads the whole image in memory like a normal scanline image
