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OBJConverter manual

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Version History

Version 3.0b1 3/11/08
	- Compatibility with X-Grinder
	- VRML support dropped
Version 2.0b2 9/27/05
	- Bug fix for animation
Version 2.0b1 9/20/05
	- Support for OBJ8

OBJConverter is a utility that converts 3-D models from various file formats to X-Plane object version 7 or 8 files. An X-Plane object file (.obj) contains geometry and texture information describing one 'object' for X-Plane scenery. An X-Plane object can be one building or many nearby buildings, contain only a few polygons, or be a detailed model. Typically you create an object in a 3-D modeling program like AutoCad, 3D Studio Max, LightWave, SketchUp, OBJectMaker, etc., and then convert it to an X-Plane object version 7/8 file for use in scenery.

OBJConverter can also convert files to 3DS or DXF format. This can be useful in case you need to do additional editing, but converting the objects sometimes removes information from the object files.

Warning: the OBJ format described here is X-Plane's OBJ format, which is totally different from the Alias/Wavefront OBJ format. This program does not work with WaveFront files!


System Requirements and Installation

OBJConverter requires OS X 10.2 (10.3 recommended) or Windows 98 SP2 or newer. Generally it will run on any machine that can run X-Plane.

Simply decompress the .zip file; to use OBJConverter with X-Grinder, make sure that both applications are in the same folder!

Using OBJConverter

To use OBJConverter with X-Grinder, simply start X-Grinder, then drag OBJ files Into the X-Grinder window.

To use OBJConverter from the command-line, the syntax is:

./OBJConverter <flags> <conversion> <input file> <output file>


Conversions can be "lossy", meaning not all data can be converted from one format to another. In particular, OBJ7 files will lose OBJ8-only features and OBJ8 files will lose OBJ7only features. Try to do the minimum number of conversions, and try to avoid round-trip conversions (e.g. 3DS to OBJ and back.)

Conversion Formats

OBJConverter can convert from the following formats:

3DS, DXF, OBJ (versions 2, 7 and 8)

It can export to:

OBJ versions 7 and 8, 3DS and DXF.

Here are some conversion limitations:

DXF: This format does not support textures or texture coordinate information.
3DS: This format does not support lines or lights.
OBJ7/8: These formats do not support multiple textures or hierarchical structure.

When a format does not support a feature, the information will be stripped. So for example if you convert an object from OBJ7 to DXF you will lose your texture coordinates and information. If you convert from OBJ8 to 3DS you will lose your lines. If you convert from DXF to OBJ8 you will lose your layers.

Generally you should avoid converting from OBJ to another format when possible. Use OBJ as your final destination format for shipping, but use your modeler's native format for editing. (Think of this like using Photoshop: when you save as a PNG you lose your layers. If you edit the PNG you won't get them back. The same problem happens with modeler structures and groups when converting to OBJ.)

Usually 3DS is the best format to convert from for textured objects.

The command-line conversion flags are:


Conversion Settings

Here is a list of the conversion settings from the menu bar. Please note that the conversion options only apply to conversions from DXF, or 3DS; for OBJ files the settings are always defaulted to the correct settings for OBJs.


You may choose either inches, feet or meters for the conversion. This is the distance that 1 "unit" length in your source object will hold in the X-Plane world. OBJConverter cannot read any kind of unit hints from your source files. Usually a 3d program will always export a file with the same units. The default is meters.

Command line: --inches, --meters, --feet

Center Object Horizontally

When this object is checked, the object will be moved horizontally so that an approximate center of the object is used as the anchor point in X-Plane. (The object will rotate around this point in World Editor too.) Use this option if your object appears far away from the placement point in World Editor.

Command line: --center

Flip X, Y or Z Axis

OBJConverter can flip the orientation of any of the axes in the object. However this may cause polygons to face in the wrong direction and become invisible. This is provided as an advanced option only.

Command line: --flip_x, --flip_y, --flip_z

Polygons Are Clockwise/Counterclockwise

This defines the orientation of a polygon's vertices when facing it from the outside of the object. Most 3-d programs use counterclockwise polygons. (X-Plane uses clockwise polygons; OBJConverter will swap as necessary.)

Y Axis Is Up/Z Axis Is Up

This defines which axis faces up in the model. Most 3-d programs use the Z axis to indicate up. However, others use the Y axis for up. X-Plane always uses the Y axis; OBJConverter will rotate your model as needed.

Command line: --axis_y, --axis_z

Saves as OBJ7

This is OBJConverter's default setting and causes OBJConverter to save all output as X-Plane 7 .obj files.

Command line: --obj7

Saves as OBJ8

This causes OBJConverter to save all output as X-Plane 8 .obj files.

Command line: --obj8