metashape-round-trip

Metashape Round-Trip

Overview

After cleaning terrain meshes in Blender, they can be sent back to Metashape for photo-texturing. This produces high-quality textures from the original photographs, applied to the cleaned geometry.

Prerequisites

• Cleaned meshes in Blender (terrain-cleanup-pipeline complete)
• Metashape project open with the same chunk that produced the original meshes
• metashape-mcp server running

Workflow

Step 1: Export from Blender

For each tile to re-texture:

1. export_obj(path="/path/to/exchange/Tile_X-Y.obj", object_name="Tile_X-Y")
2. OBJ format preserves geometry and UVs
3. Axis convention: forward=-Z, up=Y (matches Metashape expectations)

Step 2: Import into Metashape

Using metashape-mcp tools:

1. import_model(path="/path/to/exchange/Tile_X-Y.obj", format="obj")
2. Verify model imported correctly

Step 3: Build Texture in Metashape

Using metashape-mcp tools:

1. build_uv(mapping_mode="generic", texture_size=8192)
2. build_texture(blending_mode="mosaic", texture_size=8192, ghosting_filter=True)
3. Mosaic blending produces the sharpest results for road surfaces

Step 4: Export Textured Model from Metashape

Using metashape-mcp tools:

1. export_model(path="/path/to/exchange/Tile_X-Y_textured.fbx", format="fbx", save_texture=True)

Step 5: Import Textured Model into Blender

1. import_fbx(path="/path/to/exchange/Tile_X-Y_textured.fbx")
2. Verify texture is applied
3. Verify geometry matches (face count should be same or very close)

Coordinate System Notes

Stage	Forward	Up	Units
Blender export (OBJ)	-Z	Y	meters
Metashape import	auto-detected	auto-detected	meters
Metashape export (FBX)	auto	auto	meters
Blender import (FBX)	-Z	Y	meters

Common Pitfalls

• Scale mismatch: If the re-imported model is 100x too large or small, the CRS units in Metashape may be degrees instead of meters. Check Metashape chunk CRS.
• Texture not appearing: Blender may not auto-assign the texture to a material. Check the material's image texture node.
• UV overwrite: Metashape's build_uv will create new UVs. The top-down projection from Phase 5 of cleanup will be replaced.