X3DOM is able to use several kinds of geometry formats. Besides the common X3D geometry nodes, there is a non-standardized, optimized BinaryGeometry node available in X3DOM. Instead of including a text-based description of the geometry data (for instance, vertex positions), it uses external binary files. This is very useful for several purposes: First of all, binary data is usually more compact, which means that you can save bandwidth. Second, your HTML page will look much less cluttered, since it does not contain the large sets of vertex and index data any more. Finally, a third advantage is that you

The InstantReality platform provides its users tools to help them better understand and optimize their (possibly large) 3D data sets. One such tool is AOPT that (among other things) can help you in various ways to optimize 3D models with a special focus on scene-graph data. You can get it here. Please note that AOPT is free for non-commercial use. If you want to use it in commercial projects, please obtain a license first.

While on Windows and Linux the aopt tool is simply located in Instant Reality’s bin folder, on Mac it is sort of hidden here:

        
    /Applications/Instant Player.app/Contents/MacOS/aopt  
        

AOPT is a powerful command line tool that comes bundled with InstantReality. If you have InstantReality installed, opening your command line and entering “aopt” will provide you with a list of all available command line arguments and some examples of its usage. A very basic procedure, for example, would be to convert a file that InstantReality can open (e.g. in obj, ply or wrl format) into an X3D file:

        
    aopt –i myFile.foo -x myResult.x3d
        

You can also directly convert any input to an X3DOM HTML page:

        
    aopt –i myFile.foo -N myResult.html
        

To create optimized BinaryGeometry nodes, you can, for instance, use the following command with this example file:

        
    aopt –i myModel.x3d -F Scene:"cacheopt(true)" -G binGeo/:c -N example.html
        

Here, two new commands have been used to process the model data. The "-F" command merges all parts with the same material together. It then performs a cache optimization by re-arranging geometry data for faster rendering, and finally splits the resulting parts again in order to fulfill a 16 bit index limit, as it is present with WebGL 1.0. The second command, "-G", performs the actual conversion to X3DOM BinaryGeometry. It exports a compressed ("c" = "compact") version of the model, referring to binary files in the folder "binGeo". The resulting X3DOM nodes are contained in the "example.html" file.

You can, of course, also export to BinaryGeometry without previous optimization. By specifing and additional "a" flag (e.g., "-G binGeo/:ac"), the exporter will use a non-indexed version of the mesh automatically, in case the index limit of WebGL can not be met by the model data ("a" = "autoindex").

In the example file below, you can find an optimized model, created by the above AOPT example line, using the BinaryGeometry node.

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