Scene Unit Conversions for Other 3D Tools

When importing or exporting objects or scenes between Shade3D and other 3D tools, the scene units and coordinate system must be considered. Conversions for each 3D tool and file format are described below.

3D Tool Scene Information

Scene units and coordinate systems are different for each 3D tool.
Some conversions can be done using the default units for the scene.
Coordinate systems describe 3D space using either a right-handed coordinate system or a left-handed coordinate system. In a right-handed coordinate system, with the Y axis pointing up, the Z axis stretches towards the user. In a left-handed coordinate system, with the Y axis pointing up, the Z axis stretches away from the user.
The vertical axis measure values in the vertical direction of 3D space.
Negative values in the scaling elements of individual Shade3D parts or joints may cause backward faces after exporting to another 3D tool. Shade3D tries to prevent these problems by explicitly reversing the faces before export as necessary. The conditions under which this is done are indicated by "Faces reversed with negative scaling" in the tables below.

3D Tool	Scene Units	Coordinate System	Vertical Axis	Uses Negative Scaling To Flip The Face
Shade3D	mm	Right-handed	+Y	---
Unity	m	Left-handed	+Y	O
Maya	cm	Right-handed	+Y	O
3ds Max	inches	Right-handed	+Z	O
iClone (3DXChange)	cm	Right-handed	+Z	x
modo	Automatic conversion	Right-handed	+Y	O
Rhinoceros	mm	Right-handed	+Z	x

modo's scene units are converted automatically. When importing objects from Shade3D they are passed in mm.

Exporting to DXF from Shade3D

The DXF format does not contain scene unit information. It is necessary to do a unit conversion that matches the units of the destination 3D tool.
3D tools in which the scene units can be changed are listed with the default scene units in parentheses, such as "(cm)."

3D Tool	Scene Unit Conversion	Description
Maya (cm)	1.0/10.0x	3DFACE must be enabled for import. Because the coordinates are rotated 90 degrees about the X axis, coordinate conversion is necessary.
3ds Max (inches)	1.0/25.4x	3DFACE must be enabled for import. When importing the file in 3ds Max, a size conversion is not necessary if the imported file units are set to millimeters.
modo	1.0x	Faces are flipped.
Rhinoceros (mm)	1.0x	---

Exporting to OBJ from Shade3D

The OBJ format does not contain scene unit information. Surface attribute information is exported.

3D Tool	Scene Unit Conversion	Description
Maya (cm)	1000.0/10.0x	---
3ds Max (inches)	1000.0/25.4x	When importing the file in 3ds Max, a scene unit conversion is not neccessary if the model units are set to meters.
modo	1.0x	---
Rhinoceros (mm)	1000.0/1.0x	Because the coordinates are rotated 90 degrees about the X axis, coordinate conversion is necessary.

Exporting to 3DS from Shade3D

The 3DS format does not contain scene unit information. Surface attribute information is exported.

3D Tool	Scene Unit Conversion	Description
Maya (cm)	---	No 3DS import in Maya
3ds Max (inches)	1.0/25.4x	---
modo	1.0/25.4x	---
Rhinoceros (mm)	1.0x	---

Exporting to COLLADA from Shade3D

The COLLADA format contains scene unit and vertical axis information. Exporting to COLLADA from Shade3D sets the scene units to cm and the vertical axis to +Y.

3D Tool	Scene Unit Conversion	Description
Maya (cm)	1.0x	---
3ds Max (inches)	1.0x	---
modo	0.01x	The default units for COLLADA import/export under modo's System Preferences are meters. Wireframes exist, but no faces.
Rhinoceros (mm)	---	No COLLADA import in Rhinoceros

Exporting to FBX from Shade3D

The FBX format contains scene units and vertical axis information.
Export options are specified under "Description." If unspecified, the default values are used.

3D Tool	Scene Unit Conversion	Description
Unity	1.0x	Vertical axis: Y Scale: 1.0 FBX units: cm Faces reversed with negative scaling: On Embed image in FBX file: On
iClone (3DXChange)	1.0x	Vertical axis: Z Scale: 1.0 FBX units: cm Faces reversed with negative scaling: Off Export normals of face vertices: On Embed image in FBX file: On
Maya (cm)	1.0x	Vertical axis: Y Scale: 1.0 FBX units: cm Faces reversed with negative scaling: On
3ds Max (inches)	1.0x	Vertical axis: Z Scale: 1.0 FBX units: cm Faces reversed with negative scaling: On
modo	1.0x	Vertical axis: Y Scale: 1.0 FBX units: cm Faces reversed with negative scaling: On
Rhinoceros (mm)	1.0x	Vertical axis: Z Scale: 1.0 FBX units: mm Faces reversed with negative scaling: Off Export normals of face vertices: Off If vertex normals are exported the file will not load properly in Rhinoceros.

Exporting to STL from Shade3D

The STL format does not contain units or surface attribute information.
Export options are specified under "Description." If unspecified, the default values are used.

3D Tool	Scene Unit Conversion	Description
Maya (cm)	1.0/10.0x	Vertical axis: Y Scale: 0.1
3ds Max (inches)	1.0/25.4x	Vertical axis: Z Scale: 0.03937
modo	---	No STL import in modo
Rhinoceros (mm)	1.0x	Vertical axis: Z Scale: 1.0

Importing DXF in Shade3D