What are multipatch features?
A multipatch feature is a GIS object that stores a collection of patches to represent the boundary of a 3D object as a single row in a database. Patches store texture, color, transparency, and geometric information representing parts of a feature. The geometric information stored in a patch may be triangles, triangle fans, triangle strips, or rings as illustrated below.
All multipatches store z-values as part of the coordinates used to construct patches. While it is possible to model the base z-value of a multipatch using a numeric feature attribute, this option may not support all the same analysis and interaction options that are available when using embedded z-values.
Some multipatch features are considered closed, meaning they properly define a volume. Closed multipatches may be used in additional analysis tools, such as Union 3D and Intersect 3D. For a multipatch to be considered closed, it must be constructed in the correct fashion. The feature must represent one distinct volume. The patches it is composed of must all have the same counterclockwise orientation of their coordinates and participate in defining the shell of the volume. The patches must not intersect each other, and there must be no gaps or empty spaces in the shell. You can use the Is Closed geoprocessing tool to verify that a multipatch is properly closed.
Examples of multipatch features include textured buildings, lamp posts, trees, subsurface geologic formations, underground structures, or certain types of analytic surfaces.
How do I create a multipatch feature class?
To create a new multipatch feature class, simply choose Multipatch Features from the Type drop-down menu when defining the feature class's geometry.
What do the z-values represent?
Z-values are used for representing the shape and elevation of your multipatch features. The values can represent absolute heights or relative-to-ground heights. Both methods are fully supported in the display and analysis of the resulting 3D feature class.
The units and datum for a feature class's z-values should be defined on the containing feature dataset (if one exists) or on the feature class itself (if there is no feature dataset). If no units are defined, ArcGIS will assume that the z-units match the x,y units. This assumption can be problematic, particularly if x,y units are geographic (latitude-longitude).
How do I create multipatch features?
Multipatch features can be created by importing existing 3D models into ArcGIS using geoprocessing tools. The Layer 3D To Feature Class geoprocessing tool will convert points symbolized by a variety of model formats (such as SketchUp, OpenFlight, 3ds, or COLLADA) to a multipatch feature class. The Import 3D Files geoprocessing tool will do the same but provides more import format options such as VRML. In addition, multipatch features can be constructed programmatically using ArcObjects.