multipatches

Multipatches are a 3D geometry construct used in geographic information systems and 3D modeling to represent complex shapes as a collection of individual surface patches. Each patch defines a portion of the surface, typically with a defined patch type and an ordered list of vertices in a common coordinate system. A multipatch stores multiple patches together, allowing the overall object to be built from simpler, sometimes non-contiguous surfaces. Patch types may include triangles, quadrilaterals, or more complex arrangements, and patches can carry attributes such as normals, texture coordinates, and material properties.

In use, multipatches enable efficient storage and rendering of detailed 3D features such as buildings, terrain features, and architectural models. They are especially common in GIS workflows for city-scale 3D visualization and analysis, where a single feature may be composed of many patches to represent facades, roofs, and volumes with sharp edges and textures.

Data and formats: Multipatches are supported in Esri's ArcGIS and related 3D GIS tools, typically stored in a 3D geodatabase or similar container. They can be created from 3D scans, BIM models, or photogrammetric outputs, and can be exported or converted to triangle meshes for use in game engines, rendering tools, or 3D viewers.

Advantages and limitations: The patch-based structure allows precise control over surface boundaries and textures, and can simplify editing of complex geometry. However, topology across patches is not always guaranteed, editing is patch-local, and performance depends on the number and size of patches. Software support for full multipatch semantics varies between platforms.