Heightmap vs lithophane: same input, different print goal

Heightmaps and lithophanes both convert image brightness into geometry, but they are not the same workflow. A heightmap is meant to be viewed directly as a relief surface. A lithophane is meant to be viewed with light passing through it. That difference changes the default thickness, smoothing, contrast and even how the image should be inverted.

What a heightmap does

A heightmap turns brightness into visible surface height. Bright areas can become raised or low depending on the invert setting. The resulting print is read by shadows, touch and surface contour. It works well for embossed photos, terrain-like surfaces, plaques, decorative panels and relief artwork that will be seen under normal light.

What a lithophane does

A lithophane turns brightness into thickness for backlighting. Dark image areas are usually thicker so they transmit less light, while bright areas are thinner so they glow. The front surface may look subtle or strange without a light source, but the image appears when light passes through the printed material.

Smoothing matters differently

Heightmaps can tolerate stronger surface texture because the texture is the point. Lithophanes usually need smoother transitions, especially for photographs, because harsh height steps become visible bands when backlit. Too much smoothing can remove detail, but too little can create a noisy print that looks rough under light.

Choosing resolution

Use mm per pixel based on final physical size. A small lithophane does not need the same mesh resolution as a large wall panel. For most browser-generated STL or 3MF reliefs, 0.2 to 0.3 mm/pixel is practical. Smaller values create heavier files and slower slicer operations, and they only help if the printer can physically reproduce the detail.

Print orientation

Flat heightmaps are usually printed face-up. Lithophanes are often printed vertically because vertical printing can improve tonal detail and reduce visible layer stepping across the image. The best orientation depends on the model, filament, printer and desired surface finish, so always check preview and test a small crop if the print is large.