placementmaps

Placement maps are raster images used in computer graphics to guide the distribution and placement of objects, decals, or effects on a surface. They function as a form of weight or density map, rather than a height or color map, and are sampled at surface coordinates to decide where instances should appear and how they should vary.

A placement map encodes placement data in its channels. Common practice assigns density to one channel (often the red channel), while additional channels can carry attributes such as scale, rotation, or tilt. This allows a single image to control multiple aspects of instancing, enabling more complex and varied distributions. Artists typically combine placement maps with random seeds or procedural noise to avoid uniform repetition and to add natural variation.

Applications of placement maps span several areas. In terrain work, they guide the distribution of vegetation, rocks, and debris. In architectural or environment scenes, they can place decals, clutter, or props in a controlled yet varied manner. In procedural pipelines, placement maps work alongside density, orientation, and size controls to produce repeatable but non-uniform results.

Creation and workflow consider a few practical points. Placement maps are often painted by hand for artistic control or generated procedurally from noise and feature masks. It is important to ensure consistent tiling, alignment with surface features like slope or curvature, and compatibility with the engine’s instancing system. When used thoughtfully, placement maps offer repeatable control over scene density while maintaining natural variation.

See also: density map, weight map, foliage system, procedural texturing, instance-based rendering.