Conversion of units in 3DS format

Written by László Nagy

When saving a perspective from the 3D Window as 3D Studio format (*.3DS), one has to specify in millimeters or inches the unit to which dimensions of the model should be converted to in the resulting 3DS file. Originally, the DOS version of 3D Studio was always expecting dimension data in inches. That was its default dimension unit. In 3D Studio MAX, however, there is a setting in Preferences called 'Default Units'. Because of these added options the conversion can go wrong if not the correct procedure is followed.

There is a checkbox in 3D Studio MAX called 'Convert Units'. Here is an extract from the 3DS MAX Reference Guide:
"Convert units: when selected, 3DS MAX assumes units in the imported file to be in inches, and converts them to the current system of units. When unselected, 3DS MAX assumes the units in the imported file match the current system unit and doesn't convert the units..."

There are possible two cases:

1. ArchiCAD saves dimension in inches in the 3DS file, but the default unit in 3D Studio MAX is not inches (it is meters, for example). In this case, the 'Convert Units' checkbox should be activated for correct conversion of sizes.
2. ArchiCAD saves dimension data in millimeters (for example, sets drawing unit in the 3DS file to '1000 mm'). In this case one must not check the 'Convert Units' checkbox in 3D Studio MAX, and he needs to set 1 meter (1000 mm) for default unit.

   Page last updated: Thursday, September 16, 2004