Free tools for simplifying environment 3D models include Blender’s Decimate Modifier, MeshLab’s Simplification Filters, and Meshmixer’s Reduce function.
Blender’s Decimate Modifier lowers polygon count via percentage or triangle limits while keeping key shape details—ideal for game or AR/VR assets. MeshLab’s filters (like Quadric Edge Collapse) efficiently handle large scanned environments. Meshmixer’s Reduce preserves surface features, useful for 3D printing or real-time rendering.
For beginners, start with Blender: its built-in tutorials make it easy to add the Decimate Modifier and adjust settings to balance detail and file size.