OBJ 3D Model Viewer

View OBJ 3D model files with MTL materials and texture support in an interactive 3D scene.

Tested tool guide Tested browser tools Checked August 16, 2026

What OBJ 3D Model Viewer does, with a checked example

OBJ 3D Model Viewer opens Wavefront OBJ geometry as an interactive scene that can be rotated and inspected from different viewpoints. It interprets vertex and face records, then applies referenced MTL material assignments and texture images when those companion files are available. The common surprise is that an OBJ is often not self-contained: the OBJ may name a separate MTL file, which may itself name separate image files. Loading only the OBJ can therefore produce correct geometry with plain or missing surface appearance.

Worked example

A concrete input and expected output from the current implementation.

Input

A file named triangle.obj containing:
o Triangle
v 0 0 0
v 1 0 0
v 0 1 0
f 1 2 3

Expected output

An interactive scene containing one flat triangular face in the XY plane. Its coordinate bounds are x = 0 to 1, y = 0 to 1, and z = 0, giving spans of 1 by 1 by 0 model units.

The face record joins OBJ vertices 1, 2, and 3 using OBJ's one-based indexing. The triangle has perpendicular base and height lengths of 1, so its geometric area is 1 x 1 / 2 = 0.5 square model units.

How the result is produced

Geometry records

An OBJ describes positions with v records, texture coordinates with vt records, and vertex normals with vn records. Each f record connects indexed values into a polygonal face. Face entries can identify only a position or combine position, texture, and normal indexes with slashes. The viewer turns those relationships into the mesh shown in the interactive scene.

Material references

An mtllib statement in the OBJ names a material library, while usemtl assigns one of that library's materials to subsequent faces. The MTL can name texture images, including a diffuse image through map_Kd. For the intended appearance, referenced MTL and image filenames must remain available and match their references. These local assets are processed in the browser and are not uploaded.

Good uses

Inspect the shape and face layout of an OBJ downloaded from an asset library before importing it into a modeling project.
Check whether an exported OBJ, its MTL file, and its texture images still resolve after the files have been renamed or moved.
Orbit around a mesh to investigate reversed-looking faces, unexpected shading, misplaced texture coordinates, or materials assigned to the wrong surface.

Limits and checks

OBJ coordinates do not declare a standard real-world unit. A span of 1 could represent one millimeter, centimeter, meter, inch, or an arbitrary modeling unit.
A gray or untextured model does not necessarily mean the geometry is damaged. The MTL file, an image file, or a matching filename may be missing.
A successful preview confirms that the viewer can display the supplied mesh, but it does not establish that every OBJ feature or material directive will appear identically in another application.

Common questions

Why does the OBJ load but show no textures?

The faces can be valid even when their appearance files are absent. Check that the OBJ's mtllib name matches the supplied MTL file, that its usemtl names exist in that file, and that texture filenames referenced by the MTL are also present. If the OBJ contains no texture coordinates, an image cannot be mapped as intended.

Can the viewer determine the model's size in millimeters or inches?

No. OBJ stores coordinate values but does not define what physical unit those values represent. The viewer can show the model's proportions and coordinate-space extent, but it cannot infer whether one coordinate unit means a millimeter, inch, meter, or something else. That interpretation must come from the exporting application or accompanying documentation.

References and verification

The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.