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glTF – Runtime 3D Asset Delivery
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KTX2 for non-color data #1815

Open lilleyse opened 4 years ago

lilleyse commented 4 years ago

First of all, I'm very excited to see the development on KHR_texture_basisu.

We're looking at using KTX2 as an image format for storing non-color data, specifically uint16 and floating point data. We're working on a glTF extension for adding generic per-vertex and per-texel metadata to models and KTX2 seems like a good alternative to png/jpeg since data types are more clearly defined.

One example might be a per-texel "accuracy" that describes the the error in meters along a photogrammetry model compared to the ground truth. This can be stored in a KTX2 image using the VK_FORMAT_R32_SFLOAT format.

With this use case in mind there's still rationale to support baseline KTX2 in glTF. Maybe there's a chance of reviving https://github.com/KhronosGroup/glTF/pull/1612 or creating a new extension for this use case.

Also see https://github.com/CesiumGS/glTF/pull/1 for more details on the feature metadata extension.

pjcozzi commented 4 years ago

Maybe there's a chance of reviving #1612 or creating a new extension for this use case.

One approach is to create an extension for this per-texel accuracy use case that uses KTX2 to store the texels in VK_FORMAT_R32_SFLOAT and then see if we gain any insights on how a more generic KTX2 extension for glTF could work. The concern is that today the data types have well-defined semantics such as color and normals; KTX2 has several data types and the runtime would not know what to do with them without additional semantics.