This geometry import converter reads in FBX files. This import converter allows support for all major features in FBX files including support for polygon meshes, trimmed NURBS surfaces, NURBS curves, bicubic or linear patches, geometry hierarchy, lights, cameras, animation and mesh skinning.

The following is an example whereby an animated and skinned set of Samurai warriors were imported from a FBX file and rendered + animated in Okino's NuGraf software.

FBX 'Samurai' model (courtesy of Kaydara/Alias/Autodesk) imported, animated & rendered in Okino's NuGraf.
Click on any image to view a Windows Media 640x480 animation (2.3MB download).

Major Features of FBX importer

1. Reading of all FBX supported geometry including polygons, trimmed NURBS surfaces, NURBS curves and patches. Geometric and vertex normals will be computed for geometry without such information.
   
   
2. Import of materials, textures, texture mapping, lights and cameras.
   
   
3. Full object hierarchy import into NuGraf/PolyTrans with user selected hierarchy optimization algorithms.
   
   
4. Import of character skinning information.
   
   
5. Import of camera animation, lights animation, object animation and fully skinned character animation. Import of all animation FCurve interpolation types (constant, linear or cubic) as well as all tangent modes (auto, TCB, user, break).

Current Limitations of the FBX File Format

During the development of the FBX importer the following entities were found to not be supported by the FBX file format and/or related SDK which otherwise can be supported by the Okino core database and Okino .bdf cross package transfer file format. Support from Autodesk for these missing capabilities may be added by them in the future:

1. Unique mesh index arrays are not available for vertex texture uv's and vertex normals. This means, for example, 3 polygons which share one common vertex must be specified using 3 vertices, 3 uv's and 3 normals instead of one vertex, 1 to 3 uv's and 3 normals. Fundamentally this means that vertices, uv's and normals have to be duplicated even though some may be shared between adjacent polygons. This can lead to "smoothing group" problems in export file formats unless all redundant coordinates are removed prior to export.
   
   
2. No strict use of pivot information. Okino's policy is to convert explicit rotation pivot information (orientation and translation of the pivot axis) for each object. The standard FBX converters embed the pivot point data into the mesh data and thus are not converted in explicit form (although there are mechanisms in FBX to change pivot contexts).
   
   
3. No support for Inverse Kinematics IK chain and joint information. An IK chain is typically defined by a pointer to a root IK node in a skeleton and an IK end effector node (the bottom of the IK chain). Each bone/joint between the root node and end effector node form the "IK Chain", and each joint has various parameters such as joint rotation limits, damping effects, etc.
   
   
4. No support for object-to-object constraint data.
   
   
5. No support for material and texture parameter animation.

Some of these missing components of the FBX file format may be added over time by Autodesk, but since they are not core parts of the original file specification there is no guarantee that the current FBX plug-in for your 3D application will also be able to support such updated entities; it would be up to each FBX partner company to augment their FBX plug-ins to handle such extended entities in the future.

Current Limitations of the Okino FBX File Importer

1. "Cluster deformations" are not supported. Clusters are typically found in XSI and Maya. This is termed "Additive" deformations in the FBX SDK. Okino's SDK and .bdf file format supports "mesh deformations via skeleton joints and bones (mesh skinning)".

Import Translation Explanations

The following sections provide a cursory overview about how many of the elements of a FBX file are imported and converted to the internal Okino scene graph database:

Geometry Import Translations

In FBX format, geometry can be represented as polygon meshes, trimmed NURBS surfaces or bicubic patches. Patches can be Bezier, Bezier Quadratic, Cardinal, BSpline or Linear. The FBX importer will convert all patches to NURBS surfaces during import. If you deselect the NURBS import checkbox, you will also be implicitly deselecting the import of any patches into NuGraf/PolyTrans. If you select to import NURBS and to convert them to polygon meshes by enabling the "Convert NURBS to Meshes" checkbox, then any imported patches will also be converted to polygon meshes.

NURBS Import Translations

NuGraf/PolyTrans imports all types of trimmed NURBS surfaces (open, closed or periodic) currently implemented in the FBX format. All closed and periodic NURBS patches will be converted to open NURBS during import.

NURBS Limitations:

Textures on NURBS may not have accurate UV co-ordinates. Even if NURBS are converted to Polygons on import the UV co-ordinates on the resulting polygons may still not be accurate (in this case, the UV co-ordinates will be determined by using a spherical projection onto the geometry in question).

FBX Geometry	NuGraf/PolyTrans Geometry
N - sided Polygons	N - sided Polygons
Open NURBS	Open NURBS
Closed NURBS	Open NURBS
Periodic NURBS	Open NURBS
Patches	NURBS

Materials Import Translations

The FBX importer supports ambient, diffuse, specular and emissive colors as well as opacity, shininess and reflectivity. Phong, Blinn and Lambert FBX shading models are all supported.

FBX Shading Model	NuGraf/PolyTrans Shading Model
Blinn	Blinn
Lambert	Blinn
Phong	Phong
* any other shading model	Blinn

FBX Material Parameter	NuGraf/PolyTrans Material Parameter
Opacity	Opacity
Shininess	Shininess (100x bigger than FBX Value)
Reflectivity	Reflectivity
Ambient	Ambient
Diffuse	Diffuse
Specular	Specular
Emissive	Luminous

Texture Import Translations

Imports per-polygon texture mapping, texture scaling and texture modulation.

Texture Import Limitations:

Currently any texture rotations are not imported into NuGraf/PolyTrans.

Lights Import Translations

Point, directional and spot lights are imported. Since FBX spotlights have a position and an orientation, whereas NuGraf/PolyTrans spotlights have a position and a shine-at location, any spotlights will be converted have equivalent position and shine-at settings.

These FBX items will not be imported:

1. Global Light Settings
2. All Fog related setting are not imported:
   1. Fog Color
   2. Fog Density
   3. Fog Start and End
   4. All Shadow related settings are not imported:
   5. Shadow Intensity
   6. Shadow Planes

The only parameter imported from the Global ambient light in FBX is the color of that light.

Since lights are imported into their own hierarchy list in NuGraf/PolyTrans, they may need to reparented in the destination application to their original position in the object hierarchy in order to maintain their correct settings.

FBX Gobos are not imported.

Cameras Import Translations

There are 2 types of camera's in FBX - Global cameras and User Defined cameras.

Note: if a user defined camera is the default camera in an FBX scene, then all camera specific parameters and animation is lost on this camera during import.

Since cameras are imported into their own hierarchy list in NuGraf/PolyTrans, they may need to reparented in the destination application to their original position in the object hierarchy in order to maintain their correct settings.

A camera has a Look-At Node in the FBX format. If this Look-At Node for a particular camera is set to any node that doesn’t have the FBX root node as its direct parent, then animation data for this Camera may not be converted properly.

Skinning Import Translations

The FBX format supports what are referred to as the "Normal, Total1 and Additive" skinning modes. This importer and the Okino scene graph supports the Normal and Total1 modes completely but not the Additive mode. The Additive mode is equivalent to what is referred to as "point clusters" in other applications such as Maya.

Limitations & Problems of Importing "Bind Poses" from FBX File Format

In order to import skinning correctly it is essential to import the unique global bone and mesh Bind Pose. Due to known issues with the FBX SDK, it is sometimes not possible to get these critical Global Bind Poses, as sometimes only the relative "bone to mesh" transformations are known during import. The FBX importer applies a certain algorithm to attempt to determine these global bind poses.

If it is known that the correct Bind Poses were imported, then no warning messages with respect to this are output to the importer's message window. If however, the importer is unsure of whether or not the correct Bind Poses were detected, then a warning message is sent to the console.

FBX Skinning Mode	NuGraf/PolyTrans Skinning Mode
NORMALIZE	Mesh Skinning
TOTAL1	Mesh Skinning - extra bone added at mesh centre
ADDITIVE	Not Supported

Animation Import Translations

FBX format includes support for multiple animation "Takes" within a single file. When there is more than a single animation take available within an FBX file, the drop down listbox labelled "Take" in the FBX import dialog box will be populated with all available takes in the FBX file in question. Select the desired take to import.

During animation import, you can choose to maintain animation data in it's native representation where possible or to resample the animation keyframe data.

Animation Import Limitations:

Quaternion animation is usually the preferred method for animations of rotational quantities, but these are not currently supported in the FBX format.

F-Curve translations

Although Okino software does support many different kinds of F-Curve representations, there are minor differences in the internal representations of animation F-Curves. The table below illustrates these differences.

FBX FCurve Interpolation	NuGraf/PolyTrans FCurve Interpolation
All Constant	Constant
All Linear	Linear
All Cubic with TCB tangeant mode.	TCB
All Cubic with mixed auto, user, break or TCB tangeant modes.	Bezier
Mixed Interpolation types.	FCurve is resampled at 15fps and the interpolation type set to Linear.

FBX FCurve Extrapolation	NuGraf/PolyTrans FCurve Extrapolation
Constant	Constant
Slope	Gradient*
Repetition	Cycle*
Mirror Repetition	Cycle (not true mirror repetition)

* - Different terminology used between FBX and NuGraf/PolyTrans, but these modes are exactly equivalent i.e. 'Slope' is equivalent to 'Gradient' and 'Repetition' is equivalent to 'Cycle'.

Dialog Box Options

Report Statistics about the geometry file

If you enable this checkbox, statistics about the imported FBX file will be displayed in the console. Statistics will be displayed for the following:

1. Version of the imported file
   
   
2. Currently used FBX SDK Internal Version

Note: that the above version numbers are those returned from the Autodesk SDK. This seems to have different version numbers to the external version numbers of the FBX SDK. The external FBX SDK version number that is in use in this importer is FBX SDK v3.6.1. It is a known issue that files created with FBX SDK v3.6.0 and v3.6.1 are both currently reported with the same internal version number (the numbers reported by the FBX SDK v3.6.1) of 5.0.0. This is unfortunate as some known errors mentioned in this importer document apply only to v3.6.0 FBX files and not to FBX v3.6.1 files but the reported file versions are currently both 5.0.0. If you are experiencing any issues with FBX files and you have recently installed newer software that can re-create these FBX files, then it would be worth your while to do this as certain issues have been resolved in moving from v3.6.0 to v3.6.1. Hopefully, this will be addressed in future FBX SDK releases.

Statistics will also be displayed for the number of:

1. Polygons imported
   
   
2. NURBS surfaces imported
   
   
3. NURBS curves imported
   
   
4. Cameras imported
   
   
5. Lights imported
   
   
6. Surfaces imported
   
   
7. Textures imported
   
   
8. Animation F-Curves imported
   
   
9. Animation Keyframes imported
   
   
10. Joints imported

Print Warning Messages

This will print all warning messages to the importer's console. When there is any doubt that the import of data is less than ideal, this will result in a warning message being printed to the console. A warning does not necessarily mean that any degradation of data has occurred or that an error has occurred.

Note that deselecting this option will only cause warnings to be suppressed, not statistics or errors. If there is an error that would cause the importer to abort, then this is printed to the console when the process is aborted regardless of whether or not the "Print Warning Messages" option has been checkmarked.

Selective Loading

This group box allows the user to selectively import specific objects.

Polygon Import

If checkmarked then all polygonal meshes will be imported.

NURBS

If checkmarked then all NURBS surfaces will be imported.

Note: If you checkmark this option, the option to "Convert NURBS to Polygons" will become available in the "NURBS Import" group box.

NURBS Curves

If checkmarked, then NURBS curves will be imported.

Materials

If checkmarked, then of the material definitions will be imported.

Textures

If checkmarked, then all of the texture definitions will be imported.

Skinning

If checkmarked, then all of Skinning information will be imported.

Lights

If checkmarked, then all lights will be imported.

Cameras

If checkmarked, then all cameras will be imported.

NURBS Import

Convert NURBS to Meshes

If checkmarked all NURBS surfaces will be converted to polygons on import. Note that if checkmarked, all patches will also be converted to polygons.

Geometry Processing Options

These options provide methods to remove redundant hierarchy nodes from the imported FBX file.

Hierarchy Optimzier # 1

Removes runs of empty folders, as well as folders with no children.

Hierarchy Optimizer # 2

Is simpler, deleting empty folders which only have 1 geometry object in them.

Optimize Number of Objects

This compresses all objects of yellow folders into single objects and then cleans up the hierarchy to reduce the number of nodes.

Animation Import

If this checkbox is enabled, the animation import controls determine the animation import options. A FBX file can contain zero or more "Takes" of animation. The Animation "Take" listbox selects the particular animation take to import (or is grayed out if the FBX file does not contain any animation takes).

Object Animation Enable
Camera Animation Enable
Lights Animation Enable

These checkboxes control whether object, camera and/or light animation data is imported.

Resample All Imported Animation

If this checkbox is enabled then all FBX animation data will be passed through the Okino animation resampler.

NOTE: camera and light animation is ALWAYS resampled when being imported into the Okino scene graph. To avoid excess number of light and/or camera animation keys we recommend that you enable the "Perform keyframe reduction" using the default options; if you do not want the object animation to be keyframe reduced then set the reduction threshold to 0.0 or 0.00001.

Perform keyframe reduction

If this option is enabled then an algorithm will be applied to the imported keyframe lists to reduce the number of redundant keys. The type-in values determine the threshold criteria for keeping or removing a key from a list.

Distance Threshold

This numeric value indirectly controls how many redundant keyframes are to be removed from the re-sampled keyframe list. Higher values will cause more keyframes to be removed. This value is the maximum ‘distance’ the new keyframe list is allowed to deviate from the original re-sampled keyframe list. Take for example a sphere that is animated along a path; if this threshold value is set to 0.01 distance units (which is the default) then redundant keyframes of the animated path will be removed until such point that the sphere begins to deviate by more than 0.01 units from its ‘ideal’ location. In other words, if the value is set to 0.01 then you are guaranteed that the new reduced keyframe list will move the sphere along the same path in space, except that the sphere is allowed to deviate by 0.01 units from its original path. Smaller numbers will make the sphere adhere closer to its original path, but at the expense of retaining more keyframes.

Angular Threshold (degrees)

This is the same as the previous numeric value except that it applies to reduction of quaternion and Angle/axis rotation keyframe lists. The value is measured in degrees. For example, if set to 0.01 (the default) then redundant keyframes will be removed from a keyframe list until such point that a rotation angle begins to deviate from its ideal angle by more than 0.01 degrees. Small numbers will cause less deviation and more precise rotation conversions, but at the added expense of retaining more keyframes.

Specify Password

FBX files can be password protected. In order to import a password protected FBX file, you need to check this box and specify the correct password.

Password

Checkmark this box if the FBX file is password protected.