feat: improved ray tracing to preserve floors

[aclauer]

Problem

Floors and other horizontal surfaces lose points due to ray clipping when more than ~1 meter from sensor.

Closes DIM-XXX

Solution

Ignore points on the same xy plane as the lidar hit from clipping. This preserves floors much better than without.

With fix:

Before fix:

How to Test

cargo test added test to ensure same plane points aren't removed

Contributor License Agreement

• I have read and approved the CLA.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ All tests successful. No failed tests found.

📢 Thoughts on this report? Let us know!

[leshy]

r u ready 2 suffer #2283

[aclauer]

r u ready 2 suffer #2283

🥲😅

[greptile-apps]

Greptile Summary

This PR fixes floor-point erasure in the ray-tracing voxel mapper by adding a z-slab protection rule: when a ray crosses z-levels, any voxel that shares the endpoint's Z index is skipped (not marked as a miss), preserving horizontal surfaces like floors.

• A new t_max early-exit is introduced so the DDA traversal loop always terminates even when z-slab voxels are continuously skipped before the shadow-distance check can fire.
• The past_endpoint flag is now also set from the parametric t_enter >= 1.0 check (in addition to the coordinate match), which correctly handles cases where the endpoint voxel is itself in the protected z-slab.
• An existing unit test is updated to match the new skipping behavior, and a new ground_clipping_single_ray test with an assert!(total_clipped == 0, …) guard is added.

Confidence Score: 5/5

The change is safe to merge; the z-slab skip and t_max early exit are internally consistent and the new regression test with an assertion guards against future breakage.

The core logic is sound: the DDA loop terminates through the t_max exit when z-slab voxels are continuously skipped before the shadow-distance check can fire, parametric t_enter correctly identifies shadow territory, and the endpoint voxel is always visited before the z-slab filter applies. No defects in the changed paths were found.

No files require special attention.

Important Files Changed

Filename	Overview
dimos/mapping/ray_tracing/rust/src/main.rs	Adds z-slab floor protection and t_max early exit to find_misses_along_ray; updates existing DDA test and adds new ground-clipping regression test with assertion.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[Loop start] --> B["t_enter = min(tx, ty, tz)"]
    B --> C{t_enter > t_max?}
    C -- Yes --> D[return — shadow zone exceeded]
    C -- No --> E{t_enter >= 1.0?}
    E -- Yes --> F[past_endpoint = true]
    E -- No --> G[Step DDA to next voxel]
    F --> G
    G --> H{x,y,z == endpoint?}
    H -- Yes --> I[past_endpoint = true; continue]
    H -- No --> J{"origin_voxel.z ≠ endpoint.z AND z == endpoint.z?"}
    J -- Yes --> K[skip — z-slab floor protection]
    J -- No --> L{past_endpoint?}
    L -- Yes --> M{dist_sq > shadow_sq?}
    M -- Yes --> D
    M -- No --> N[mark as miss if in map]
    L -- No --> O{dist_sq < grace_sq?}
    O -- Yes --> K
    O -- No --> N
    N --> A
    K --> A
    I --> A

Loading

_{Reviews (2): Last reviewed commit: "Enforce planar condition in test" | Re-trigger Greptile}

[aclauer]

r u ready 2 suffer #2283

#2304

I think this might be a solution to stairs and a more general fix for floors. Would be a total experiment though.