Materials and textures#

JT conversions can preserve external and embedded image textures using the existing Material Type setting. No separate texture option is required. None omits image textures and uses display-color and opacity primvars with the default display-color material. That default material also exposes roughness and metallic controls.

Supported textures and UVs#

  • Base-color textures using Replace blending.

  • Tangent-space normal maps.

  • Opacity textures using Replace blending.

  • Two-dimensional mesh UV sets named st, st1, through st7.

Textures must use Repeat wrapping and an identity texture transform. Preview Surface and MaterialX OpenPBR textures can select their source UV channel. OmniPBR supports only st; textures selecting another channel are skipped with a warning. Materials with different images or UV selections remain distinct.

RGB color images retain scalar opacity. RGBA color images replace scalar opacity with image alpha; alpha is not multiplied by scalar opacity. A separate opacity image is generated when needed. Alpha extraction supports eight-bit pixel data.

Source UVs are separate from Generate Projection UVs, which remains disabled by default. Leave projection generation off to retain source mapping; explicitly requested optimizer operations can change the output.

Image files and portable output#

For local output, images are copied into Textures/ beside each USD file and referenced with relative paths. Keep the images and referenced USD files with the output when moving it. Identical image filenames and contents can be reused; different contents receive a numeric suffix instead of overwriting an existing image.

For Nucleus output, the extension transfers generated images and USD dependencies into a separate asset folder beside the requested USD file. Keep that folder with the root USD. A transfer failure is reported as a conversion failure. Assets from an earlier export are not automatically removed when overwriting its root USD.

External images retain their format; the renderer must support it. The converter looks relative to the source JT file, then for the image basename beside that file, then through the USD asset resolver. Keep externally referenced images accessible on the conversion machine. Downloading a JT file from Nucleus does not automatically download its external image library; stage the JT and external images locally with their expected paths when necessary. Embedded images travel inside the JT file.

Supported embedded eight-bit formats are RGB, RGBA, BGR, BGRA, luminance, luminance with alpha, and alpha; these are written as TGA images. If an external image cannot be inspected, a warning is reported and it is used as RGB without extracted opacity.

Source image paths can be absolute or refer to parent directories. Services accepting untrusted JT files should restrict the converter process to the intended input files; referenced paths are not limited to the JT folder and are not validated as image files before copying.

Unsupported settings and diagnostics#

The converter warns and skips unsupported settings, including:

  • Decal or Modulate blending, height bump maps, and environment maps.

  • Non-Repeat wrapping and texture transforms.

  • Multiple textures targeting one material input.

  • Instance-specific texture overrides.

  • OmniPBR textures selecting a UV channel other than st.

A missing image or UV set leaves the corresponding scalar material input in place. Inspect conversion logs and the resulting materials: a successful conversion does not guarantee every texture was supported. These warnings do not introduce an incomplete-output status for JT.

In-memory output#

For direct converter API calls using an anonymous USD layer, external images use resolved source paths. Embedded image export and alpha extraction require a file-backed output destination. Without one, the converter warns: external RGBA images still supply color while scalar opacity remains unchanged; opacity-only textures requiring alpha extraction are skipped.