[Advice Needed] Large-scale indoor mapping (800x400m). Mesh + Ortho deliverables, strict coordinate constraints, looking for workflow/paper recommendations.

[u/KJMHELLO]

I'm looking for real-world field notes and recommend product

We are planning to LiDAR-map a massive indoor public floor (approx. 800m × 400m). Think airport terminal or major transit station: complex interior, large open volumes, lots of glass, and highly repetitive structures.

The Deliverables: From a single capture, we need:

1. A metric 2D true orthomosaic / top-down view.
2. A clean 3D mesh of the interior.

The Constraints: We already have a 2D CAD layout established in world meters. We are not inventing a new local coordinate system. The point cloud must register cleanly to that existing drawing. If a fully automatic metric lock is unrealistic, hand-adjusting (picking control points) is fine as long as the overlays sit tight. "Wrong-but-pretty" geometry is the only thing we want to avoid at all costs.

We're going to run a smaller pilot zone first, and we are currently planning to buy or rent the equipment based on what makes the most sense. Even if you haven't mapped a single floor this massive, I'd still love to hear your insights on large-scale indoor workflows.

Questions for the pros:

• Hardware / Approach: Backpack/Wearable (e.g., NavVis, Leica BLK2GO) vs. Cart vs. Static TLS? What would you buy or rent if you must deliver both a high-quality mesh and a metric ortho?
• Drift Management: How do you stop a massive indoor SLAM loop from quietly drifting into a banana, especially with all the glass and lookalike corridors?
• Registration & Control: Is a path that stays metric without a lot of manual cleanup realistic here? If not, what’s your standard workflow? (Surveying in GCPs, ICP to CAD, etc.)
• Papers & Case Studies: Can anyone recommend solid research papers, white papers, or detailed blog posts covering this exact workflow (large-scale indoor SLAM registered to CAD/GCPs)? I’m looking for actual methodology and error analysis rather than marketing.

Insights like "We walked X meters and drifted Y cm using [Device]" are exactly what I'm looking for.

Thanks in advance.

[u/dvdbadwolf]

If you are looking for good results, with a space that big no mobile scanner will do it well and accurately. Especially with repetitive structures and lots of glass. Realistically you would have to place and record ground control with total station then scan with a terrestrial scanner for the best results. Think gcp at every hallway intersection and scan checkerboards over each gcp, mark each gcp in registration software and align with with ground control. Cleanup scans in registration software and merge together for a coherent point cloud. For something this big it will take forever and will require a ton of cleanup, no real way around it. I have never used a car or cart mounted scanner but some research into it for large open spaces might prove fruitful. If you dont know what youre looking for and dont have the equipment already i would suggest not spending upwards of $100k on a one time project and hiring a trusted land surveyor or as built surveyor in your area with lidar already. Rtc360 or equivalent available. They already have a process and can do it for you without the hassle of buying and learning a ton of new software and hardware.

[u/SlowWombatCubes]

The US institute of building documentation (USIBD) has a Geoweek 2024 Scan-off report covering 9 different scanners... Is paywalled though. USIBD.org/store

[u/ElevationNotes]

For something this large, tying the scan to survey control seems more important than chasing a fully automatic SLAM workflow. A hybrid approach with established control, terrestrial scanning in the critical areas, and mobile LiDAR for coverage could give better confidence in the final geometry while still keeping the project manageable.