Scene Graph Traversal, Child Nodes First

FBX Node Types and How they are translated into Viz Scene Tree Items

Avoid Transformations Being Baked

If unsupported features are detected the transformations of those nodes are Baked, which means that individual transformations are not retained in a Viz Scene. The transformed vertices are in the Viz Scene, but with all transformation parameters reset to their default values.

To avoid this make sure that unsupported features are not used in a Scene and, ideally, that the FBX properties which import into the same transformation in a Viz Scene are not used at the same time:

• Do not use a scaling offset: An extra offset applied after rotation and before scaling. It depends on the modeling application if it is available and under which name. To be on the safe side try to limit this to the regular translation and the rotation pivot.

• Do not use a separate scaling pivot: This can be tricky, depending on the 3D modeling application. In Maya the two pivots move together by default, which keeps the possibility to map them both to a single axis center in Viz Engine. If the modeling application moves the rotation pivot separately by default, and objects are scaled afterwards, there are two transformations based on different pivots. Viz Engine has to bake the results to reflect them correctly.

FBX Import: Avoid Separate Scaling Pivot

Avoid Transformations Being Combined

If, during import, two FBX properties have to be combined into a single property in Viz, they cannot be animated separately anymore. Limitations are not fully specified yet, since animation import is still under development, but to keep 100% the same control over transformations as in the original scene it is a good idea to consider these tips:

• Do not use a rotation offset.

• Do not use geometric translation/rotation/scaling in 3ds Max.

• Do not use unit conversion (see Export FBX Files from 3ds Max and Maya).

• Do not use axis conversion.

  • FBX uses a Y-up axis system, this is also the default setting for the FBX export. If the modeling application uses a different axis system it applies pre-rotation of ± 90° to all objects to change the orientation of the Scene to match the FBX axis system. This can interfere with animation.

  • Maya uses a Y-up axis system by default so all pre- and post-rotations are set to zero, which is perfect. If the modeling application uses another axis system (for example, 3ds Max uses Z-up) and problems occur it is possible to select a different option in the ‘Axis Conversion’ section in the FBX export settings, so that no corrective rotation has to be applied.

To Export FBX Files from 3ds or Maya

1. From the File menu in Maya 2013, select Export (All)… or Export Selection….

2. Select a directory and enter a filename.

Units

It depends on each modeling application how units in virtual 3D space correspond to real world units. The default working unit is centimeters. When a Scene is exported choose a scale factor in the FBX export dialog, the option is named File units converted to and can be found in section Advanced Options > Units.

The table below shows how units import from Maya into Viz Artist when different settings are used:

Maya Units Imported into Viz Artist

Materials

Viz Engine supports one material per mesh node. The first material found on a FBX node is imported into a Material object, which is then applied to the Viz Container.

Materials with Viz Classic Render Pipeline

Supported FBX material classes are Lambert Shading and Phong Shading. Both types of shading have there own set of parameters which are described in more detail in the tables below:

Lambert Shading

Phong Shading

Other Materials

Other kinds of material which the modeling application supports may be mapped to a FBX Lambert or Phong material by the exporter, at least the parameters which are compatible to those material types.

Materials with Viz Engine Render Pipeline

The main material used in the Viz Engine Render Pipeline is the PBR Material. The importer either imports "Stingray PBS" materials from Maya or tries to derive some basic values from any other Material available in the .fbx file.

Stingray PBS

This is the preferred material to be used when using Maya in combination with Viz Engine, because the channels directly map from Maya to Viz Engine.

Other Materials

For all materials where .fbx is able to create a so called Surface Material (usually Lambert and Phong), a PBR Material is created, where a few basic parameters are imported.

Textures with Viz Classic Render Pipeline

FBX can associate a texture with each color channel on a material.

Textures are referenced by the FBX file through their path and filename by default. This feature is broken in the current FBX SDK provided by Autodesk (the exported file may contain an absolute path and in some cases this path is not correct, even on the machine where the file was created). Texture images can be embedded into the FBX file which is a lot more robust. Tick the check-box Embed Media in the export dialog to enable this.

Camera

Currently up to 16 cameras are imported. The import is limited and can give little more than the correct camera position and direction. Dependent on the transformations that have been applied to a camera, and additional parameters unique to the modeling application, the camera position and viewing parameters can deviate a lot after import.

Lights with Viz Classic Render Pipeline

The lights detailed below are supported, but not all their parameters are imported:

Supported Lights

The only animation properties imported for Lights are:

• Translation

• Cutoff / Cone Angle (because hardware accelerated OpenGL lights are limited, this is unlikely to produce the exact same effect produced in the modeling software)
  Color animation is not imported because it requires separate channels for red, green and blue components.

Spotlights

For performance reasons Viz Engine only supports the standard OpenGL light parameters.

OpenGL Spotlight Parameters and Corresponding Light Parameters in Viz

FBX translates a modeling application’s spotlight parameters to an inner and outer cone angle. During import into Viz the exponent is approximated based on the inner angle of the spotlight. Results can be different from what is seen in Maya or 3ds.

Exponent in Maya

Maya has an alternative spotlight parameter, Dropoff, which corresponds directly to the OpenGL parameter Exponent. With the Viz Artist VizFbxExtension plug-in, this parameter can be exported. This allows work with real GL-spotlight parameters in Maya and gives a viewport lighting much more faithful to the actual rendering results in Viz. Without the VizFbxExtension plug-in, Maya does not export that parameter, because no other Autodesk product supports importing it.

Lights with Viz Engine Render Pipeline

In contrast to the Viz Classic Render Pipeline, lights are now directly imported in the Viz Engine Render Pipeline as container plug-in. The following light types are supported:

VizUUID Plug-in Installation

• When Installing Viz, make sure you have the Maya FBX Export component selected.

• This installs all necessary files into the Viz Engine subfolder export/FBX. Standard installation path is C:\Program Files\vizrt\VizEngine\export\FBX.

• Adjust your MAYA_PLUGIN_PATH so that it points to the folder above. Please refer to your Maya documentation on how to do this.

See Also

• Import of Files and Archives

• Export FBX Files from 3ds Max and Maya