Swept Path Optimization Tool
Houdini Tool (Retopology)
Project Description
This Houdini tool was built to optimize the output of my Snapshot tool. The Snapshot workflow captures an animated ride or mechanism as a dense series of static meshes—one per sampled frame—which combine into a single "blob" that describes the full swept-path envelope. That blob is accurate but extremely heavy: thousands of overlapping, self-intersecting surfaces. This tool turns it into a clean, watertight, dramatically lighter mesh while preserving the true shape of the motion.
The original use case was representing the dynamic motion path of robotic ride systems in a way that is both accurate and efficient—light enough to hand off for clearance studies, layout, and review, without discarding the real geometry of the envelope. It works by voxel retopology: the combined snapshot meshes are converted into a single VDB volume and then rebuilt as polygons at a controllable resolution, unifying the overlapping surfaces into one solid. A single Voxel Size knob trades fidelity against polycount. The same pipeline has since been used to clean up and optimize engineering models for 3D printing.
You can see the tool, the sample files, and the documentation on Github.
How It Works
| Step | What it does |
|---|---|
| The Pipeline | |
| Import combined swept path | Reference Imported Mesh. A File SOP reads the merged "blob" of static snapshot meshes—OBJ, FBX, or bgeo exported from the Snapshot tool or any DCC—so the whole swept envelope enters Houdini as one input. |
| Voxel retopology | Voxelize Snake. The thousands of overlapping snapshot surfaces are converted into a single VDB volume, fusing the self-intersecting meshes into one watertight solid that follows the true shape of the motion. |
| Convert back to polygons | Convert Back to Polys. The VDB is rebuilt as clean polygon geometry with a large reduction in polycount—an efficient, review-ready mesh instead of a heavy stack of snapshots. |
| Controls & Comparison | |
| Voxel Size | A single knob on the voxelize step trades accuracy against weight—closer to zero means smaller voxels that hug the original shape more tightly at a higher polycount; larger values give a coarser, lighter result. |
| Color & alpha compare | Set Color / Set Alpha / Adjust Visibility. The optimized mesh is tinted and faded against the original swept path so you can overlay the two and confirm the envelope is preserved before exporting. |
| Import & Export | |
| Works with any source | Accepts swept paths generated in Blender (via the Snapshot add-on), 3ds Max, or Maya—anything that can write out a combined static mesh. |
| Geometry export | Right-click the optimized output node and choose Save > Geometry to write the reduced mesh back out as an OBJ (or other geometry format) for clearance studies, layout, review, or 3D printing. |