Overview
VRayTexBitmap allows you to load texture maps in a native to V-Ray manner. Most of the Nuke nodes will not affect it (color corrections for example), still, it will be faster than the regular Read node. Additionally, this is the only node you can use to load a texture if you wish to export your scene to a .vrscene and render it with V-Ray Standalone.
UI Path: ||Toolbar|| > V-Ray menu icon > Textures > VRayTexBitmap
Parameters
File – Sets the path to the texture file.
Filter type – Specifies the V-Ray internal texture filter.
No filter – No filtering is performed.
Mip-map – Uses pyramidal MIP map filtering to compute the texture color.
Summed-area – Uses a summed-area table (SAT) to compute the texture color.
Elliptical filtering – Uses high-quality anisotropic MIP map texture filtering that reduces blurring and aliasing artifacts.
Pre Filter Radius – Specifies the size of the filtering radius.
Format – Sets the size of the file. Typically it is guessed correctly from the file header, but you can change it to set a different pixel aspect ratio if required.
UV Tiling Mode – Specifies the type of UV tiling used by the texture. See the Tags for Multi-Tiles section for additional information.
Auto-detect – V-Ray will detect the type of tiling automatically.
Off – Disables UV tiling.
UDIM – Uses UDIM tiling for the texture.
UVTILE – Uses UVTILE tiling for the texture.
Explicit – U and V values are entered explicitly.
zero-based – Specifies if the UV tiling method is zero-based where the UV coordinates start at 0.
Color space – Sets the lookup table (LUT) used to convert from this file to the internal values used by Nuke.
default (autodetects the color space based on file extension)
Linear
Gamma corrected – Uses the value from the Gamma slider.
sRGB
Gamma – Sets the gamma multiplier for the node.
No UVW Color – The color when there are no UV coordinates.
VRay Sequence – The VRayTexBitmap can also be used to load a sequence of images in order to use an animation as a texture. To do that load the first frame of the animation in the File field and enable this checkbox.
Frame offset –Shifts the start frame.
Tiled OpenEXR and TIFF Files
This texture can also be used to efficiently load tiled OpenEXR and tiled TIFF files (tiled TIFF files usually have a .tx or .tex extension). Tiled OpenEXR and TIFF files allow only portions of the textures to be loaded at various resolutions. This allows V-Ray to load only the parts of the textures that are needed for the rendering.
You can convert many common image file formats to tiled OpenEXR files using the img2tiledexr tool. Conversion to tiled TIFF can be done using the maketx tool from the OpenImageIO library.
Tiled TIFF files have the advantage that they can store 8-bit color components, whereas OpenEXR stores at least 16 bits. This means that tiled 8-bit TIFF textures are smaller on the disk and take up less RAM while rendering.
Tags and Environment Variables in Bitmap Names
VRayTexBitmap allows the use of named tags enclosed with the characters < and >, which are replaced at render time with other strings.
Tags for Multi-Tiles
Some modeling applications allow specifying a different bitmap file for different portions of a model based on the UV coordinates of that model. For example, one file may be used for UVs in the range [0,0] x (1,1), another file may be used for UVs in [1,0] x (2,1) and so on. There are several ways to specify the correct file for each tile, and in each case, a different format for the file name is used in the File node. This is done by using special tags in the file name, which are replaced at render time with a particular string based on the UVs of the current shading point.
In the following section, we assume that each UV tile has unique integer coordinates (u,v) based on the integer part of the UVs inside it. For example, the UV tile [0,0] x (1,1) has coordinates (0,0), the UV tile [1,0] x (2,1) has coordinates (1,0) and so on.
Uppercase tags usually assume the tile coordinates start from 1, whereas lower-case tags assume the tiles start from 0.
Mari Tiles and the <UDIM> Tag
Mari forms the file name of textures using a four-digit number equal to 1000+(u+1+v*10). So the UV tile [0,0] x (1,1) is assigned the number 1001, UV tile [0,1] x (1,2) is assigned 1011 and so on. To specify a Mari-style tiled texture, use the <UDIM> tag in the file name, which is then replaced with the respective four digits, for example, my_texture_<UDIM>.exr becomes my_texture_1001.exr and so on during rendering.
Mudbox Tiles and the <UVTILE> Tag
Mudbox can form the file name in many ways, but the default format is to use _uU_vV in the file name where U=u+1 and V=v+1 are the tile coordinates plus one. So the UV tile [0,0] x (1,1) is marked with _u1_v1, UV tile [0,1] x (1,2) is marked with _u1_v2 and so on. To specify this format, use the <UVTILE> tag in the file name. If you use lower case letters <uvtile>, then the tile coordinates will start from 0, instead of one, so tile [0,0] x (1,1) will be resolved to _u0_v0 and so on. For example, my_texture<UVTILE>.exr becomes my_texture_u1_v1.exr and so on during rendering.
The $U and $V Tags
You can also specify the u and v coordinates of the tiles separately by using the $U and $V tags. Each of them is expanded to the respective 1-based coordinate of the tile. For example, if the file name is specified as my_texture_$U_$V.exr, this becomes my_texture_1_1.exr and so on. You can use lower-case tags to make the tile coordinates start from zero, instead of 1, for example, my_texture_$u_$v.exr becomes my_texture_0_0.exr and so on.
You can put a number right after the $ sign to specify how many digits you want in the resulting tile coordinates, for example, my_texture_$2U_$2V.exr is expanded to my_texture_01_01.exr and so on.
Environment Variables
You can include environment variables in the form ${VAR_NAME} which are replaced with the value of the respective environment variable during rendering. For example, if the file name is specified as ${TEX_PATH}\${PROJ_FOLDER}\mytexture.exr, then V-Ray will look up the environment variables TEX_PATH and PROJ_FOLDER and replace the tags with their values. Suppose that TEX_PATH is set to c:\textures and PROJ_FOLDER is set to proj1, then the final bitmap file name will be expanded as c:\textures\proj1\mytexture.exr
User Attributes in the VRayObjProp
You can use the VRayObjProp node to specify User Attributes (between the < and > brackets) for objects in the scene. At render time, V-Ray takes the tag name and looks it up in the node's User Attribute for the shaded object to determine the value of the tag. This allows a single VRayTexBitmap texture to use different files on different scene nodes. For example, you could specify the file name in VRayTexBitmap as c:\path\to\texture\<objtag>_diffuse.png and then for the objects that use the material add a VRayObjProp node and then add a User Attribute string with values like objtag=head or objtag=body, etc. Then during rendering, V-Ray will attempt to load and use the texture file c:\path\to\texture\head_diffuse.png for the first object and c:\path\to\texture\body_diffuse.png on the second.
Notes
- The texture file can be previewed in the postage stamp of the node itself as well as in the 3D viewport.