The UV Remap operator allows you to map video or images onto 3D surfaces using UV maps exported from 3D software. This technique is commonly used for virtual product placement, mapping content onto screens in 3D scenes, or applying textures to pre-rendered 3D objects.
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Overview
UV mapping is a technique where a 2D image (the UV map) contains coordinates that tell the filter where to sample from the input texture. The Red channel contains the horizontal (U) coordinate and the Green channel contains the vertical (V) coordinate.
When you render a UV pass from your 3D software, each pixel in the UV map stores the texture coordinates for that position. The UV Remap operator reads these coordinates and samples your input video/image accordingly, effectively "projecting" your content onto the 3D surface.
Quick Start
- Add the UV Remap operator to your composition (found in Special Effects)
- Click on UV Map Image and select your UV map file
- Your input will now be mapped according to the UV coordinates
Settings
UV Map
| Setting | Description |
|---|---|
| UV Map Image | Select the UV map image file. Supports PNG, JPG, BMP, TGA, TIFF, and EXR formats. For best quality, use 16-bit PNG files. |
| Reload UV Map | Button to reload the UV map from disk if the file has changed. |
UV Transform
| Setting | Description |
|---|---|
| Scale U (%) | Horizontal texture scale. 100% = normal size, 200% = texture repeats twice horizontally. Range: 10-500% |
| Scale V (%) | Vertical texture scale. 100% = normal size, 200% = texture repeats twice vertically. Range: 10-500% |
| Offset U (%) | Shifts the texture horizontally. Useful for positioning or animating the texture. Range: -100% to 100% |
| Offset V (%) | Shifts the texture vertically. Range: -100% to 100% |
| Reset to defaults | Button to reset all transform settings to their default values. |
Sampling
| Setting | Description |
|---|---|
| Tile mode | Controls how the texture behaves when UV coordinates go outside the 0-1 range. See Tile Modes below. |
| Filter mode | Controls the quality of texture sampling. See Filter Modes below. |
Tile Modes
| Mode | Description |
|---|---|
| Clamp | UV coordinates are clamped to the edge pixels. Areas outside the texture show the edge color. |
| Repeat | The texture repeats/tiles infinitely in all directions. |
| Mirror | The texture mirrors at each edge, creating a seamless repeating pattern. |
Filter Modes
| Mode | Description |
|---|---|
| Nearest | No interpolation - sharp pixels. Fastest but can look blocky. |
| Bilinear | Smooth interpolation using 4 neighboring pixels. Good balance of quality and speed. |
| Bicubic | Highest quality interpolation using 16 neighboring pixels (Catmull-Rom). Recommended for best results. |
Background (Advanced)
These settings control what appears in areas where the UV map is invalid (typically black areas in the UV map).
| Setting | Description |
|---|---|
| Background mode | What to show in invalid UV areas. |
| UV threshold (%) | Minimum UV brightness to consider valid. Increase if you see artifacts at UV boundaries. |
| Background Red/Green/Blue/Alpha | Color components when using "Color" background mode. |
Background Modes
| Mode | Description |
|---|---|
| Transparent | Invalid areas become fully transparent (alpha = 0). |
| Original | Invalid areas show the original input texture. |
| Color | Invalid areas are filled with the specified background color. |
UV Options (Advanced)
| Setting | Description |
|---|---|
| Swap U/V | Exchanges the U and V channels. Use if your UV map has the axes swapped. |
| Flip U | Mirrors the texture horizontally. |
| Flip V | Mirrors the texture vertically. |
| Use alpha for validity | Uses the UV map's alpha channel to determine valid areas instead of checking if UV values are non-zero. |
Debug
| Setting | Description |
|---|---|
| Show UV map | Displays the UV map itself instead of the remapped result. Useful for verifying your UV map is loaded correctly. |
| Show texture | Displays the input texture without any UV remapping applied. |
| Show original | Bypasses the effect entirely and shows the original input. |
Keyboard Shortcuts
| Key | Function |
|---|---|
| F1 | Cycle through tile modes (Clamp → Repeat → Mirror) |
| F2 | Cycle through filter modes (Nearest → Bilinear → Bicubic) |
| F3 | Toggle Flip U |
| F4 | Toggle Flip V |
| F5 | Toggle Swap UV |
| F6 | Toggle Show UV map |
| F7 | Toggle Show texture |
| F8 | Reset transform to defaults |
Creating UV Maps
What is a UV Map?
A UV map is an image where each pixel's color encodes texture coordinates:
- Red channel = U coordinate (horizontal position, 0-1)
- Green channel = V coordinate (vertical position, 0-1)
- Blue channel = Usually 0 (unused)
- Alpha channel = Can be used for masking valid areas
Recommended Settings for Exporting UV Maps
For best quality:
- Resolution: Match or exceed your output resolution
- Bit depth: 16-bit PNG (65,536 levels) for smooth results. 8-bit (256 levels) will show visible stepping/jagginess.
- Anti-aliasing: Disable anti-aliasing on UV render passes
- Format: PNG (lossless). Avoid JPEG as compression artifacts will cause sampling errors.
Blender
- In the Shader Editor, add a UV Map node
- Connect UV outputs to an Emission shader:
- U → Emission Color Red
- V → Emission Color Green
- Set up a render pass or use Compositor to output the UV data
- Render Settings → Output → Color Depth: 16-bit
- Save as PNG
Alternatively, use the Bake feature:
- Create a new image (16-bit, RGB)
- Select your object and go to Render Properties → Bake
- Set Bake Type to UV
- Click Bake
3DS Max / V-Ray
- Add a VRayUVWMap render element
- Render Settings → Output → 16-bit
- Render and save as PNG or EXR
Cinema 4D
- Create a new material with only a UV Mapping shader in the Color channel
- Render Settings → Save → Format: PNG, Depth: 16-bit
- Render
After Effects (for 2D UV maps)
You can create simple UV maps using gradients:
- Create a composition matching your desired resolution
- Add a horizontal gradient (black to red) as the U channel
- Add a vertical gradient (black to green) as the V channel
- Combine using blending modes or channel effects
- Export as 16-bit PNG
Tips for Best Results
Quality
-
Use 16-bit UV maps - The difference is significant. 8-bit only provides 256 discrete positions, causing visible stepping. 16-bit provides 65,536 positions for smooth results.
-
Use Bicubic filtering - This is the default and provides the smoothest results, especially important for curved surfaces.
-
Match resolutions - Your UV map should be at least as large as your output resolution.
Performance
-
Bilinear is faster - If performance is critical and quality is acceptable, Bilinear filtering is faster than Bicubic.
-
UV map size - Larger UV maps use more GPU memory. Use the smallest size that provides acceptable quality.
Troubleshooting
| Problem | Solution |
|---|---|
| Image looks jaggy/stepped | Use a 16-bit UV map instead of 8-bit |
| Image is mirrored or rotated | Try Flip U, Flip V, or Swap UV options |
| Black areas in output | Adjust UV threshold or change Background mode |
| Texture appears stretched | Check that your UV map was rendered with the correct aspect ratio |
| Colors look wrong | Ensure your UV map uses Red=U, Green=V convention. Try Swap UV if needed. |
Example Use Cases
Virtual Product Placement
Map video content onto screens, billboards, or product surfaces in pre-rendered 3D scenes.
Motion Graphics
Apply animated textures to 3D text or shapes rendered from 3D software.
Projection Mapping Preview
Preview how content will look when projected onto physical surfaces.
Texture Animation
Animate the Scale and Offset parameters to create scrolling or zooming effects on 3D surfaces.