LOD Generator

This guide explains how to use the VR LOD Generator in SimLab Composer to optimize large scenes for a smooth, high-performance VR experience.

What is LOD (Level of Detail)?

LOD is a system that swaps a 3D model with lower-polygon versions in real-time to save processing power. The switch between levels is determined by two main criteria:

• Distance: How far the user is from the object.

• Screen Coverage: How much space the object takes up in the user's field of view.

1. Pre-LOD Optimization

Before generating LODs, you must reduce "draw calls" (the number of separate objects) and clean up materials.

• Selection Rule: Expand groups and select individual assemblies (e.g., all separate chairs) rather than just the single top-level parent assembly.

• Step 1 (Materials): Merges identical materials and optimizes texture sizes/compression.

• Step 2 (Merge Objects): Combines parts within each assembly to reduce complexity while keeping objects distinct from one another.

2. Identifying "Heavy" Objects

The plugin provides a surgical way to find which objects are taxing performance:

• Filter: Set a Minimum Polygon count to populate the plugin table with complex objects.

• Analyze & Zoom: View exact polygon counts in the table. Clicking any item in the table will automatically zoom the camera to that object in the scene for inspection.

3. Creating & Managing LODs

Define your decimation percentages for each level. Note that LOD 0 represents the model when the user is closest to it; decimating this level reduces the polygon count of the "original" model itself.

• LOD 0: Initial decimation to optimize the model at its closest distance.

• LOD 1 & 2: Increasing levels of reduction for mid-to-far distances.

• LOD 3: Enable the Hide option to completely remove distant objects from the render.

• Global Settings: Use this to determine if the system swaps levels based on Distance or Screen Coverage.

Watch This Tutorial to Learn more