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Input Files

SpeedTree Engine works primarily with a new file type called STE (SpeedTree Engine), introduced in SpeedTree Cinema 8.2. STE is a special variant of SPM, designed specifically for use with SpeedTree Engine. When STE files are exported, all possible textures the tree model might use are included, which is a different set than the SPM file uses. This different (and often much larger) texture set adds:

  • Seasons: Every possible season configuration (e.g. summer, winter, and fall versions of the leaf textures), not just the textures visible at the time of export, as is done with traditional mesh exports like OBJ or FBX. This makes it possible to randomly access seasons from within the Engine API.
  • Artistic Tuning: The effects of individual texture adjustments in Cinema (e.g. brightness, contrast, saturation) are baked into a new set of textures so they'll work in multiple rendering environments.
  • Variations: When enabled upon export, the color variations of each material, as defined in Cinema, are also baked into a new set of textures – one new texture per variation.

All of these can result in a good number of additional textures, but it’s necessary in order to capture the Cinema material definitions accurately. It ensures Cinema will work correctly with external applications and renderers.

Exporting STE Files From Cinema

Exporting is accessed from the “File” pulldown menu in Cinema, specifically “File → Export mesh…”. There are several different mesh types supported. Be sure to select (*.ste) from the options. Once selected, you'll have several options in the popup dialog, including:

  • Format: The format the textures will be written in. All formats will preserve the sRGB color space of the original models from the official SpeedTree library except EXR, which will export as linear.
  • Max Size: The official SpeedTree models use high resolution textures (often up to 8k), which can be really slow to import. Cap the texture sizes with this option, especially if you're not rendering at production quality yet.
  • Skip Texture Save: It's common during modeling iterations to change the geometry of a tree model but not the materials/textures. Use this option to speed subsequent STE exports by bypassing exporting the textures, which accounts for the bulk of time for most exports.

Using SPM Files

SpeedTree Engine will read standard SPM files as well; however, there will be several issues with the materials:

  • Artistic Tuning Will Not Apply: Standard SpeedTree models from the library may appear overly bright when loaded via SPM. This is because adjustments like saturation and brightness from Cinema are not applied. The textures are accessed as is.
  • No Seasonal Changes: As the season parameter is adjusted, some materials will be missing.
  • No Variations: Material variations, as defined in Cinema, will be ignored.

SPMs are best used for rapid prototyping or when only geometry is needed.

Always prefer STE files to SPM when materials matter.