Convert OBJ to PMD

Older MikuMikuDance projects and utilities may accept only PMD models, while most modeling and scanning tools export static meshes as OBJ. The conversion transfers geometry and basic materials, but an OBJ does not contain the rigging and MMD-specific data needed for an animated character.

OBJ format

Wavefront OBJ is a text-based mesh format used by Blender, Maya, 3ds Max, Cinema 4D, ZBrush, MeshLab, CAD exporters, asset libraries, and 3D scanning workflows. It stores vertices, polygon faces, UV coordinates, normals, groups, and material assignments.

Materials and textures are usually described by a separate .mtl file. Keep the .obj, .mtl, and image files together when moving or importing the model.

OBJ has no standard representation for MikuMikuDance bones, vertex weights, IK, facial morphs, rigid bodies, joints, toon settings, edge rendering, or motion-compatible bone names. A direct import therefore creates a static mesh, not a finished MMD character.

PMD format

PMD, or Polygon Model Data, is MikuMikuDance's older model format. It can store mesh data, materials, texture references, bones, skin weights, morphs, display frames, rigid bodies, and physics joints.

PMD is required by legacy MMD software and older model pipelines. Use PMX instead when the receiving program supports it: PMX has more flexible model data, better Unicode support, additional morph options, and fewer legacy restrictions.

PMD uses 16-bit face indices, so a model cannot address more than 65,535 vertices. Its fixed-length, legacy text fields and Shift-JIS-era character handling also make short ASCII texture filenames such as body_diffuse.png the safest choice for older MMD installations.

Preparing the OBJ

1. Open the model in Blender with File → Import → Wavefront (.obj). Confirm that materials load and that texture images are found through the accompanying .mtl file.
2. Check scale, orientation, UV maps, flipped normals, overlapping geometry, and material slots. Apply transforms with Object → Apply → Rotation & Scale after the model is correctly sized and oriented.
3. Triangulate the mesh if it contains quads or n-gons. Add a Triangulate modifier, inspect the resulting edge flow, then apply the modifier before export. Older MMD tools can split non-triangular faces differently from the source application.
4. Reduce excessive vertex counts before targeting PMD, and separate materials cleanly. Bake procedural materials, node effects, or complex shaders to ordinary texture images because OBJ and PMD cannot preserve Blender material graphs.
5. Export the cleaned mesh through File → Export → Wavefront (.obj) with UVs, normals, and materials enabled. Use a simple folder path and relative texture references where possible.

Building and saving an MMD model

PMX Editor is the usual Windows editor for final MMD model work. Its available OBJ import commands depend on the installed version and plug-ins; use a maintained OBJ import plug-in only when its documentation explicitly lists your PMX Editor version. Do not assume that every PMX Editor installation provides File → Import → OBJ.

1. Import the OBJ through the editor's supported importer, or transfer the prepared mesh through an intermediate format supported by the specific tool. Verify vertex count, material assignments, UVs, normals, and texture paths before rigging.
2. Rebuild MMD material settings. Assign diffuse textures, set transparency behavior, and add toon textures, sphere maps, edge settings, and draw order only where the model needs them; OBJ material values do not map fully to MMD materials.
3. Create an MMD bone hierarchy and assign vertex weights. A movable prop normally needs at least an appropriate root or center bone; a character needs a complete skeleton, correctly weighted vertices, and MMD-compatible bone names and structure for the motions it will use.
4. Add facial or other morphs, then create rigid bodies and joints only after the mesh and skeleton work correctly. These elements cannot be inferred from an OBJ file.
5. Save a working master as .pmx when possible. If PMD is mandatory, use PMX Editor's supported PMD save/export option and reopen the result in the exact target MMD version.
6. Test texture loading, bone movement, morphs, transparency, toon rendering, and physics. Test with representative .vmd motions if the model is intended to use existing MMD animations.

Compatibility limits

Existing .vmd motion files animate bones by name and expected hierarchy. A converted mesh will not work with a motion merely because it was saved as PMD; its bones, parent relationships, orientation, and naming must match the intended motion convention.

Use relative texture paths and avoid non-ASCII filenames when distributing PMD files for older systems. Package the PMD and its texture folder together, because PMD references external image files rather than embedding them.

No reputable browser converter can turn an arbitrary OBJ into a production-ready PMD character. Online mesh converters can change geometry formats, but they cannot create reliable MMD weights, bones, morphs, physics, or toon materials; desktop editing in Blender and PMX Editor is required for those steps.