Khronos 3D Commerce glTF Asset Validation Guide

The Khronos 3D Commerce Asset Checklist establishes standardized criteria to ensure 3D models display predictably, render consistently, and perform efficiently across various e-commerce platforms and augmented reality (AR) viewers. This article details how the checklist validates real-world scale, pivot point placement, and PBR texture configurations within glTF (GL Transmission Format) assets to streamline 3D commerce deployment.

Scale Validation

In the glTF specification, one unit is defined strictly as one physical meter. The 3D Commerce checklist verifies scale by evaluating the asset's bounding box and transform hierarchies:

  • Real-World Proportions: Automated tools calculate the minimum and maximum boundaries along the X, Y, and Z axes to generate the object’s physical bounding box. These dimensions are checked against real-world product specifications to ensure a 1:1 match.
  • Transform Normalization: The checklist ensures that the root node and any child mesh nodes do not have non-uniform or unapplied scale values. Scale transformations should ideally be baked directly into the vertex data or defined uniformly as [1, 1, 1] at the node level. Negative scale values are flagged as errors because they invert face normals and disrupt lighting calculations.

Pivot Point and Origin Validation

The placement of the origin point (0, 0, 0) dictates how the 3D model spawns, aligns, and interacts within WebGL viewers and mobile AR environments:

  • Floor and Tabletop Assets: For free-standing products like furniture, shoes, or appliances, the checklist validates that the origin is situated at the bottom-center of the asset. The lowest vertices must align precisely with the ground plane (\(Y = 0\)), with the horizontal centroid aligned to \(X = 0\) and \(Z = 0\). This prevents models from hovering above surfaces or clipping through the floor in AR tracking.
  • Wall and Ceiling Assets: For wall-mounted objects (e.g., mirrors or artwork), the pivot must be aligned with the rear contact surface at \(Z = 0\). For ceiling-mounted fixtures (e.g., lamps), the origin must sit at the top contact point.
  • Transform Hygiene: The asset is validated to ensure that rotations and translations are applied cleanly, avoiding unintended coordinate offsets that would throw off camera-framing algorithms.

Texture Validation

Texture validation focuses on memory footprint, performance budgets, and fidelity within Physically Based Rendering (PBR) pipelines:

  • Dimension and Resolution: Textures are inspected to verify they are power-of-two (POT) dimensions (such as 1024x1024 or 2048x2048), which ensures compatibility with GPU mipmapping. The checklist enforces resolution caps—typically a maximum of 2048x2048 or 4096x4096 depending on platform performance tiers—to prevent excessive runtime VRAM usage.
  • Color Space Encoding: The checklist validates that textures conform to strict color space standards. Base color (albedo) and emissive maps must be encoded in the sRGB color space. Data-driven maps, including normal maps and the combined metallic-roughness-occlusion maps, must be strictly linear to prevent incorrect surface reflections and lighting errors.
  • Channel Packing (ORM): To reduce HTTP requests and GPU texture memory, glTF mandates the packing of PBR properties into a single texture:
    • Red channel: Ambient Occlusion
    • Green channel: Roughness
    • Blue channel: Metallic Validation tools check that individual channels contain the expected data ranges and that roughness and metallic values are physically plausible.
  • Compression and File Types: Standard assets are checked for valid baseline image formats (PNG or JPEG). Advanced delivery targets are validated for KTX 2.0 containers using Basis Universal compression (UASTC or ETC1S) to optimize transmission size and runtime decoding speed.