3.2 Route Planning and Coverage Strategy

The Backbone-First Approach

For any building with corridors connecting rooms, scan the main corridors first before branching into individual spaces. The corridor network is the backbone of the scan. Establishing it early means every room you branch into has a registered starting point already built into the dataset. When you exit a room and return to the corridor, you create a loop closure automatically.

Loop-Based Routes vs. Linear Paths

The single most impactful route planning decision is whether your route creates genuine loops. SLAM drift accumulates with every meter traveled. Loop closure is the correction mechanism. A route with no loops provides no mid-session corrections, all drift accumulates until the end, when it is too large to fully correct.

Creating Effective Loops

• Plan at least one midway loop for any scan lasting more than 10 minutes, return through an already-scanned area before continuing to new areas
• For large-scale sites, plan loops every 5 to 10 minutes of continuous walking
• Use doorways as natural loop closure points, enter and exit through the same door after covering the room, then cross the corridor to continue
• When returning to a previously-scanned area for loop closure, approach from the same general direction you originally scanned it, not the reverse

Serpentine and Saturated Scanning

For any open area that cannot be covered by simple loops, large rooms, parking floors, exhibition halls, use serpentine (S-shaped) routes rather than straight parallel passes. Serpentine routes naturally generate loop closures at each turn while providing overlapping coverage from adjacent paths.

For areas with significant occlusion (complex machinery, dense shelving, heavy equipment) or where scanning quality is critical, use saturated scanning: cover the same area from multiple different routes and directions rather than a single pass. This is more time-consuming but produces substantially better coverage of occluded surfaces.

Equipment and Object Coverage

Mechanical equipment, HVAC units, tanks, columns, and any object with surfaces facing multiple directions requires deliberate multi-angle coverage. A single pass captures the surfaces facing your direction of travel. Surfaces parallel to your path and surfaces facing away from you are missed entirely.

For standalone equipment and objects, circle the target at a distance of 3 to 10 feet, moving at 1.5 feet per second. Complete at least one full revolution. For complex equipment with many internal surfaces, walk figure-eights around it to capture geometry from crossing angles. For tall objects, vary your height if possible, but keep height changes gradual, with no more than 40 degrees difference in viewing angle at any single moment.

• Circle standalone objects rather than passing them once, at least one full revolution at consistent distance
• Use figure-eight patterns for equipment with internal complexity
• For ceiling-mounted equipment, approach from directly below and scan with the device tilted upward, keep the tilt under 30 degrees
• Do not attempt to capture a surface by tilting the device to an extreme angle, reposition your body to face the surface instead

Height Variation

Varying the height at which you hold the scanner during a pass adds geometry from angles that a single-height route cannot capture, tops of low partitions, undersides of mezzanines, equipment at floor level. This is particularly useful in complex industrial environments.

The constraint is that height changes must be gradual. The line-of-sight difference between successive positions must not exceed 40 degrees. Raising or lowering the device sharply by a large amount in a short distance creates a viewing angle jump that the SLAM visual system struggles to reconcile. Make height transitions slowly and over several meters of travel, not in a single step.

Site Reconnaissance Before Scanning

Walk the site without the scanner before beginning. Five minutes of reconnaissance prevents route planning decisions made under pressure once the scan is running and the clock is ticking. On a reconnaissance walk, identify the following.

• Feature-poor zones, long corridors, open areas, low-texture surfaces, and plan to slow down and use serpentine routes in those areas
• Obstructions and occlusion, dense equipment, shelving, or structures that will require additional passes
• Lighting conditions, very dark areas that need supplemental lighting, and bright transitional zones (indoor-outdoor thresholds) that require reduced speed
• Reflective or transparent surfaces, glass walls, mirrors, polished floors, and plan how to approach them (see Challenging Environments)
• Access constraints, doors that must remain closed, areas with moving machinery, personnel who may be present during the scan
• Loop closure opportunities, identify where your route can naturally cross itself to create corrections