Geometry file formats

See also: Tile block formats

Extensions	Type	Read	Write	Notes
.geo	Internal	✓	✓	Houdini ASCII geometry format.
.bgeo	Internal	✓	✓	Houdini binary geometry format
`.poly`	Internal	✓	✓	Prisms ASCII format (polygons only) This format only supports polygonal geometry types. It is included in the Geometry Editor to maintain compatibility with other, older, systems. Tip In a `.poly` file, the first point referred to by the polygons is point number 0.
`.bpoly`	Internal	✓	✓	PRISMS binary format (polygons only)
.d	Internal	✓	✓	PRISMS move/draw format (polygons only)
`.rib`	Internal		✓	RenderMan geometry
`.dxf`	External	✓	✓	Uses gdxf - polygons only, no attributes `.dxf` was invented by Autodesk for use with AutoCAD. It is a common geometry exchange format. `.dxf` format only supports polygonal geometry types. `.dxf` layers are mapped to groups when read into the SOP Editor. Texture and color information is lost if you save to a `.dxf` file.
`.obj`	External	✓	✓	Uses gwavefront - polygons only. Only `texture` and `pointnormal` attributes (groups are kept on read). `.obj` was invented by Wavefront. It is a very common geometry exchange format. `.obj` supports polygons, textures, normals, and groups.
`.pc`	Internal	✓	✓	Point cloud tile-based format, as written by pcwrite.
`.iv`	External/Internal	✓	✓	Uses ginventor. Does not support Bezier or metaball primitives. Only some attributes. Inventor format was invented by SGI for use with their 3D libraries. It supports polygons, spheres, cylinders, and NURBS.
`.wrl`	External		✓	VRML. Uses ginventor. VRML was invented for viewing and exchanging 3D data on the Web. It is descended from the Inventor (`.iv`) format.
`.sdl`	External	✓		Uses gsdl command. `.sdl` was invented by Alias/Wavefront. It was traditionally used as input to a renderer. Houdini can read `.sdl` files but cannot write them. Houdini only imports spline surface geometry (and instances of spline surfaces), and the name of each patch and shader is imported. It does not import colors and texture coordinates.
`.eps`	External	✓		Uses geps command. Houdini reads `.eps` files from Illustrator 5.5 as planar geometry. It does not import fills, patterns, or colors.
`.med`	External	✓		Uses gmed command. Houdini will read Meta Editor metaball files, although eccentric information is lost upon loading.
`.lw`	External	✓		Uses glightwave command. .lw was invented by NewTek for use with LightWave. Houdini supports objects from version 3.5 and earlier. Houdini only handles the following LightWave features: points polygons surface names (as primitive groups) surface color as primitive colors) surface transparency as primitive alpha) surface smoothing (as internal cusp operations) Houdini will ignore all other features. It cannot load files saved with layer information. The file to be loaded must contain points. However, it need not contain any polygons. Note By default, LightWave objects are rendered as faceted (no smoothing) whereas in Houdini you must explicitly cusp polygons in order to achieve this. As a result, if you load an object that has no smoothing values set (all faceted) you will end up with all points in the resulting object being “unique-ed” - giving you a much larger data set. To get around this, manually convert the file using the glightwave utility with the `-s` option.
`.ply`	External	✓	✓	Uses gply command .ply was designed at Stanford University and UNC Chapel Hill, and is mostly used for academic research and with Cyberware scanners. The `.ply` format is a polygonal format. It can handle very large data sets, and supports vertex normals and colors. Houdini can read and write `.ply` files using the gply standalone program.