This page provides information on the V-Ray Bitmap Texture.
Overview
The VRayBitmap map can be used to load high dynamic range images (HDRI) and map them onto the environment. V-Ray supports most of the standard HDRI-environment mapping methods. This texture can also be used to load other file formats.
UI Path: Texture > V-Ray > VRayBitmap
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. You can also convert all files in a scene using the V-Ray Bitmap to VRayBitmap converter script. 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
VRayBitmap 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 to specify 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.
Upper-case 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.
The <frameNum> tag
The frameNum tag can be used to specify an image sequence. V-Ray loads a sequence from the same path. To use the frameNum tag, just add <frameNum> to your texture filename.
For example, if the first image in the sequence is located at C:\textures\myImage.0001.png, change the string to C:\textures\myImage.<frameNum>.png and V-Ray will look for an image that corresponds to each frame within the animation range.
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
Bitmap Properties
Bitmap – Specifies the file name from which the bitmap is loaded. Currently supported formats are HDR, EXR, PNG, BMP, TGA, SGI, JPG, PIC, TIF, PSD, VRIMG. Image file lists in the form of IFL files are also supported.
Common
Alpha from Intensity –
Invert –
Invert Alpha –
Color Mult –
Texture –
Mix Strength –
Color Offset –
Texture –
Mix Strength –
Alpha Mult –
Alpha Offset –
No UVs Color –
Texture –
Mix Strength –
Mapped
Tile –
Placement Type –
U/V – Adjusts the texture location - specifies the location of the top left corner of the image.
Width/Height – Adjusts the width and height of the texture or crop area.
Jitter –
Tile U/V –
Processing
Filter Type – Specifies the V-Ray internal texture filtering method. Possible values are:
No filtering – Disables filtering for the texture.
Mip-map filtering –
Summed are table filtering – Pyramidal MIP map filtering is used to compute the texture color. Can be blurry for textures seen at grazing angles.
Elliptical – High quality anisotropic MIP map texture filtering that reduces blurring and aliasing artifacts. Can be slower compared to the Summed are table filtering.
Sharp Mip-Map filtering – Sharper and more accurate version of the Summed are table filtering. Produces results that are closer to the results with disabled filtering but with less AA samples required.
Filter Blur – Additional multiplier which controls filter blurring, especially useful with the mapping source feature. The higher the value, the more blurred the texture renders and the less render time it takes, and vice versa. A value of 0.01 means no filtering, but leads to increased render times. If a Bitmap is connected to the VRayBitmap as a mapping source, the Filter multiplier option serves as a multiplier for the Blur parameter of the Bitmap. For example, if the Bitmap Blur parameter is set to 10, and the VRayBitmap Filter multiplier is set to 0.1, the texture blur amount is effectively, 1.
Interpolation – Determines how the image is interpolated from the pixel values. Possible values are:
Bilinear – 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 – 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 – 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.
Allow Negative Colors –
Transfer Function –
Gamma –
Time
These options allow you to control animated textures.
Start Frame – Specifies the beginning of the texture animation. The frame number specified here will be played at the first frame of the scene animation
Playback Rate – Controls the animation speed of the texture as fraction of the actual animation speed. A value of 1 means that the texture animation will run at regular speed. A value of 2 means that the texture animation will run twice as fast as the scene animation.
End Condition – Allows you to control what happens when the last frame of the animated texture is reached. The available options are:
Loop – The animation will start again from the frame specified in the Start Frame option
Ping-pong – The animation will be played backwards until it reaches the the frame specified in the Start Frame option and then play forward again
Hold – The animation will stop at the last frame and it will be displayed until the end of the scene animation.
Noise
UV Noise On –
Animate UV Noise –
UV Noise Amount –
UV Noise Levels –
UV Noise Size –
UV Noise Phase –