OBJ — PBR Sphere referencing an MTL
A smooth-shaded sphere as Wavefront OBJ with `mtllib`/`usemtl` pointing at a sibling MTL. Downloading the OBJ alone gives you the classic missing-material case; downloading both reproduces the glTF metallic-roughness twin in this group.
Interactive preview rendered from the equivalent glTF (pbr-sphere.glb); drag to orbit. Download the file above for the OBJ original.
Specifications
- Format
- Wavefront OBJ
- Vertices
- 544
- Triangles
- 960
- Normals
- true
- Mtllib
- pbr-sphere.mtl
- Usemtl
- NovusBrushedMetal
- Smoothing Group
- 1
Testing contract
Expected to pass- Scenario
- Import the OBJ with and without pbr-sphere.mtl next to it.
- Expected result
- With the MTL the sphere is brushed metal; without it the importer must fall back to a default material and warn rather than fail.
What is a .obj file?
OBJ (Wavefront OBJ) is a text-based 3D geometry format defining vertices, texture coordinates, normals, and faces, and referencing materials through a companion MTL file. It is simple, widely supported, and can represent polygonal meshes with UV mapping. It is a common interchange format across 3D tools.
How to use this file
Use an example OBJ to test mesh and UV parsing, MTL material resolution, and importers in 3D engines, renderers, and modeling applications.
How to use this file for testing
“OBJ — PBR Sphere referencing an MTL” is a deterministic Novus Examples fixture for PBR material testing, Conversion testing. Complete PBR material sets — base colour, normal, roughness, metallic, ambient occlusion, and height — for testing material-generation models and physically-based renderers channel by channel.
Documented properties for this file: Wavefront OBJ. Compare results against paired or grouped companions on this page when present (clean↔damaged, searchable↔scanned, or format twins) so scores stay reproducible across runs.
Download the file once, keep the path stable in CI or local scripts, and treat the spec table as the contract: dimensions, seeds, field lists, and roles are intentional. Corrupt or invalid samples are labelled as such — expect parsers to fail loudly rather than silently accept them.
3D and CAD fixtures carry one small, documented solid or scene. Convert and inspect against the known geometry, units, and structure; format twins let you diff interchange fidelity, and the 3D viewer previews the actual mesh.
Code examples
import trimesh # pip install trimesh
mesh = trimesh.load("pbr-sphere.obj")
print(mesh.bounds, mesh.faces.shape)Related files
- glbglTF Material — doubleSided True vs False (GLB)Two open half-shells with identical geometry and opposite `doubleSided` flags. Because the shells are open you can see straight into them, which is the only way to tell backface culling from a lighting difference.
- glbglTF Material — KHR_materials_clearcoat (GLB)A rough red base under a full-strength, near-mirror clearcoat lobe — the two-layer material that car paint, lacquered wood and phone cases all need. The base and coat roughness differ by an order of magnitude, so a renderer that collapses the layers is obvious.
- glbglTF Material — KHR_materials_emissive_strength (GLB)Emission pushed past the core spec's 0-1 emissiveFactor clamp by a 6x strength multiplier — the extension that exists because HDR bloom needs values core glTF cannot express. A tone-mapping and bloom-threshold fixture.
- glbglTF Material — KHR_materials_unlit (GLB)A sphere whose material opts out of lighting entirely via KHR_materials_unlit — the shading path used for baked scenes, maps and stylised art. Renders as a flat silhouette in a conformant viewer and as a lit ball in one that ignores the extension, which makes the difference obvious.
- glbglTF Material — KHR_materials_variants (GLB)One mesh, two named material variants (Copper and Cobalt) selectable at runtime — the extension behind every product configurator that swaps a finish without reloading geometry. The primitive also carries a plain `material`, so viewers with no variant support still render something.
- glbglTF Material — Metallic-Roughness (GLB)A sphere with the glTF core metallic-roughness material — full metal, low roughness, no textures, so the numbers in the JSON are the whole material. The baseline half of the metallic-roughness vs specular-glossiness twin.
Generated by generation/models_p7.py. Free for any use, no attribution required — license.