Simulate Depth Maps for 3D Textures in GIMP

Simulating depth maps in GIMP allows you to generate grayscale heightmaps that define the elevation and extrusion of 3D models and textures. This article explains how to create, layer, and refine grayscale values—where pure white represents maximum height, pure black represents the base level, and gray shades define mid-level elevations—to produce accurate extrusion textures for 3D rendering engines and displacement shaders.

1. Set Up the Document in Grayscale

Depth maps rely strictly on luminance values to dictate displacement height.

  1. Open GIMP and create a new project with dimensions suited to your texture (e.g., 2048x2048 or 4096x4096 pixels for standard 3D textures).
  2. Set the color space to grayscale by navigating to Image > Mode > Grayscale.
  3. Set the precision to at least 16-bit float or 32-bit float by going to Image > Precision > 16-bit floating point. Higher bit depths prevent color banding, which causes stepping artifacts during 3D extrusion.

2. Isolate Elements and Establish Height Layers

Create individual layers for each depth plane in your extrusion map.

  1. Create a background layer filled with pure black (#000000) to represent the flat, unextruded base surface.
  2. For each elevated feature (such as text, mechanical paneling, or architectural details), create a dedicated layer.
  3. Assign a specific gray tone to each layer based on its intended height:
    • Low extrusion: Dark gray (e.g., #333333 to #666666)
    • Medium extrusion: Mid-gray (e.g., #808080)
    • Maximum extrusion: Pure white (#FFFFFF)

3. Create Slopes, Chamfers, and Rounded Edges

Flat grayscale values create sharp, vertical 90-degree extrusions. To simulate angled bevels, chamfers, or curved surfaces, you must introduce gradients.

Method A: Using Distance Map (For Bevels and Insets)

  1. Select the layer containing your isolated shape.
  2. Go to Filters > Map > Distance Map.
  3. Set the Metric to Euclidean and adjust the Threshold to control how the gradient fades from the edges inward. This generates smooth, mathematically linear slopes toward the center of your shapes.

Method B: Using Gaussian Blur (For Rounded Soft Edges)

  1. Duplicate your shape layer.
  2. Go to Filters > Blur > Gaussian Blur.
  3. Increase the Size X and Size Y sliders to soften the boundary. The resulting blur creates a rounded transition between the top face and the base surface.

4. Add Surface Micro-Details

Secondary depth variations (such as grain, scratches, or wear) add realism to the overall extrusion.

  1. Create a new transparent layer at the top of the layer stack.
  2. Generate base noise via Filters > Noise > Simplex Noise or Perlin Noise.
  3. Lower the opacity of this layer to between 5% and 15% so it does not overpower the primary extrusion shapes.
  4. Set the layer mode to Overlay or Linear Light to blend the micro-texture seamlessly across both high and low surfaces.

5. Normalize Dynamic Range with Levels and Curves

To maximize the extrusion fidelity in your 3D application, balance the tonal range across the entire image.

  1. Create a new layer from visible by selecting Layer > New from Visible.
  2. Navigate to Colors > Levels.
  3. Adjust the input black and white sliders to ensure the lowest recessed point hits absolute black and the highest extruded point hits absolute white.
  4. Use Colors > Curves to adjust the falloff curve. An "S-curve" sharpens slope transitions, while a parabolic curve rounds out the extruded shapes.

6. Export the Heightmap

  1. Go to File > Export As...
  2. Choose PNG or TIFF format to preserve lossless data.
  3. In the export dialog, ensure that the compression does not discard bit depth, and save the file with an 8-bit, 16-bit, or 32-bit grayscale color profile for direct use in displacement, bump, or normal map baking workflows.