Model Preparation

The quality of your 3D model directly affects tracking performance. This guide covers mesh requirements, what makes objects easy or hard to track, how to choose between tracking methods, and model generation.

Mesh Requirements

• Correct scale is critical — the mesh must match the real object's dimensions in meters
• Centered pivot — the mesh origin should be at or near the object center
• Unity Mesh Filters are read automatically from the TrackedBody GameObject and its children
• Holes and open surfaces are fine — the mesh does not need to be watertight. However, unnecessary internal geometry (pipes, wiring, hidden chambers) adds complexity without helping tracking. A clean exterior shell is ideal.

Scale matters

If your mesh is in centimeters but Unity expects meters, tracking will fail or be wildly inaccurate. Verify the scale by comparing the mesh bounding box to the real object's dimensions.

Simplify When Possible

An optimized model without unnecessary detail tracks better and generates faster. Remove internal geometry, hidden faces, and overly dense tessellation that doesn't contribute to the visible outline or surface edges.

Complexity	Triangle Count	Notes
Simple	< 5,000	Fast generation, good for basic shapes
Medium	5,000 - 50,000	Good balance for most objects
Complex	> 50,000	Longer generation, consider decimation

Very high-poly meshes slow down model generation and rendering but don't improve tracking quality. Consider decimating meshes above 50k triangles.

What Makes Objects Easy or Hard to Track

Good Objects for Tracking

• Distinct shape — objects with a recognizable outline from multiple angles
• Asymmetric geometry — the tracker can distinguish different viewing angles
• Clear surface features — edges, creases, and contours that are visible in the camera image
• Reasonable size — objects that fill a significant portion of the camera frame

Challenging Objects

Object Type	Why It's Hard	Suggestion
Spheres, cylinders	Featureless outline — looks the same from every angle	Add depth tracking if sensor available; edge modality won't help
Simple boxes	Very few distinct features, symmetry confuses the tracker	Works better with edge modality if the box has visible edges
Very thin/flat objects	Minimal silhouette area, weak depth signal	Ensure the thin edge is visible; may need specific viewpoint coverage
Transparent/reflective objects	Silhouette blends with background, depth sensors can't measure	Extremely difficult — consider adding opaque markers
Deformable objects	Shape changes don't match the rigid 3D model	Only works if deformation is minimal

Tip

If your object is near-featureless (sphere, smooth cylinder), silhouette tracking with depth is your best bet. Edge tracking needs geometric edges to match — a smooth surface has none.

Choosing Between Silhouette and Edge

The Tracking Method setting on the TrackedBody determines which primary modality is used:

Use Silhouette When

• The object has a distinct color or appearance against the background
• The object is curved or organic — smooth outlines work well
• You expect fast camera or object movement — silhouette is the most resilient to motion
• You're tracking from a distance where fine edges aren't visible

Use Edge When

• The object has lots of geometric detail — edges, creases, sharp corners (e.g., large machinery, engine parts, industrial equipment)
• You're tracking a partial view of a large object where only some edges are visible
• The background is cluttered or similar in color to the object — edge tracking uses local gradients, not global foreground/background separation
• The object is in a low-contrast environment — edges are detectable at lower contrast than silhouettes

Quick Reference

Factor	Silhouette	Edge
Object contrast vs background	Needs clear separation	Works with lower contrast
Fast motion	Very resilient	More sensitive
Background clutter	Sensitive	More discriminative
Best object type	Curved, distinct outline	Machinery, mechanical parts, geometric detail
Partial view of large object	Weaker (needs visible outline)	Strong (internal edges still visible)

Mesh Considerations by Modality

For silhouette tracking:

• The outer silhouette is what matters — the outline shape from each viewing angle
• Internal holes and details don't contribute to tracking (they're inside the silhouette)
• Smooth, accurate exterior geometry gives the best results
• A simple, clean mesh often tracks better than a detailed one

For edge tracking:

• Surface edges and creases are the primary features — the more geometric detail on the exterior, the better
• Internal edges visible through holes or openings do contribute — edge tracking can match them
• Accurate edge geometry is essential — if the 3D model's edges don't match reality, tracking suffers
• CAD models work particularly well because their edge structure matches the real part closely

Generating a Tracking Model (Silhouette Only)

A tracking model is only required for silhouette tracking. Edge tracking works directly from the mesh geometry — no model generation needed.

1. Select the TrackedBody in the scene
2. In the inspector, find the Model section
3. Click Generate Silhouette Model
4. Wait for generation to complete

The generated model is stored as a TrackingModelAsset — a ScriptableObject in your project. It's automatically assigned to the TrackedBody.

Tip

If you're using edge tracking, you can skip model generation entirely. Just assign the mesh and start tracking.

Viewpoint Coverage

The model generator renders the object from many viewpoints on a sphere around it. You can control which viewpoints are generated:

Vertical Coverage — Controls the elevation range:

Preset	Description
Full Sphere	All angles (default)
Upper Hemisphere	Only views from above (floor-standing objects)
Side Ring	Only views from the side (wall-mounted objects)
Custom	Manual min/max elevation angles

Orbit Radius — Distance from the object center for viewpoint generation. Pick a radius close to the distance you expect to mostly view the object from — this gives the best tracking quality at that range. Tracking still works at other distances, but quality is highest near the generation radius.

Model Settings

Setting	Description
Orbit Radius	Distance of viewpoints from the object. Set to the typical viewing distance for best results.
Subdivisions	Viewpoint density on the sphere (higher = more viewpoints = longer generation)
Points Per View	Density of sample points per viewpoint

Tips

• Test with the default settings first — they work for most objects
• If detection is unreliable from certain angles, increase viewpoint coverage for those angles
• For symmetric objects, fewer viewpoints may be sufficient
• Model generation only needs to happen once — the asset is saved in your project
• You can regenerate at any time if you change the mesh or settings
• Simplify your mesh before generating — remove internal geometry and hidden faces for faster generation and better performance