Phase 4 — LOD Generation (Blender + 3DSC)

This phase generates multiple Levels of Detail (LODs) from the textured tiles produced in Phase 3 — High-Resolution Texturing (Metashape + 3DSC Scripts). The 3DSC LOD Generator decimates geometry and bakes lower-resolution textures so the final Reality-Based file can be efficiently visualized at different zoom levels.

4.1 Import Textured Tiles

  1. Open new Blender file (or continue from previous)

  2. Import > 3DSC > Import OBJ (Ant File Importer)

  3. Navigate to 05_RB/03_Model_Library/[ModelName]/meshpolytex/

  4. Import all tiles

img/import_textured.png

Fig. 26 [SCREENSHOT: Blender with fully textured tiled model from EM structure]

Tip

If working with a very large model, you can import tiles in batches to verify quality before importing the complete set.

4.2 Verify Quality with Model Inspector

Use 3DSC’s Model Inspector to check texture resolution:

  1. Select one or more tiles

  2. Open 3DSC > Model Inspector panel

  3. Click MeanRes button

  4. Review statistics:

    • Area (m²)

    • Polygon count

    • Mean resolution (mm/pixel) - should be ~1.2mm

    • Polygons per m² - should be ~1000

  5. Click Export to save statistics as CSV

img/model_inspector.png

Fig. 27 [SCREENSHOT: Model Inspector panel showing statistics]

4.3 Set LOD0 Base

Before generating LODs, designate the highest detail level:

  1. Select all textured tiles

  2. Open 3DSC > LOD Generator panel

  3. Click LOD 0 (set as) button

This cleans and renames objects with _LOD0 suffix and proper naming convention (ob1mt1 format).

Naming Convention

3DSC uses a standardized naming:

  • ob = object

  • 1 = object number

  • mt = material

  • 1 = material number

  • _LOD0 = level of detail

This ensures compatibility with game engines like Unreal Engine.

4.4 Configure LOD Settings

Set parameters for Level of Detail generation:

  1. Number of LODs: Typically 2-3 LODs

  2. Padding: Enable padding ratio (recommended)

  3. Decimation Ratios (expressed as decimals 0-1):

    Example for 3 LODs:

    • LOD1: 0.2 (20% of LOD0 = 200 poly/m²)

    • LOD2: 0.04 (20% of LOD1 = 40 poly/m²)

    Or:

    • LOD1: 0.5 (50% of LOD0 = 500 poly/m²)

    • LOD2: 0.25 (50% of LOD1 = 250 poly/m²)

  4. Texture Resolutions:

    • LOD1: 2048 px

    • LOD2: 512 px

    • LOD3: 128 px (if needed)

  5. Export Folder: Select where LOD files will be saved

img/lod_settings.png

Fig. 28 [SCREENSHOT: LOD Generator panel with settings filled]

4.5 Generate LODs

  1. Click Generate button

  2. Monitor progress in system console

  3. The tool will:

    • Decimate geometry for each LOD

    • Bake textures to lower resolutions

    • Export LOD files to specified folder

    • Create LOD data inside the .blend file

Processing Time

LOD generation is time-intensive:

  • Small models (~10 tiles): 5-15 minutes

  • Medium models (~50 tiles): 30-60 minutes

  • Large models (100+ tiles): Several hours

See also