Handheld 3D Scanning Checklist: What to Check Before Booking

Before Booking: Key Questions to Ask

Before booking a handheld 3D scan, confirm these critical details with your scanning provider:

| Aspect | What to Confirm | | --- | --- | | Accuracy needed | ±2mm (terrestrial/TLS) vs ±5–15mm (SLAM handheld) | | Scan purpose | Scan-to-BIM, as-built CAD, heritage, volumetric, change detection | | Site conditions | Occupied? Hazardous materials (asbestos)? Confined spaces? Scaffolding? | | Coordinate system | Existing OS grid and controls needed, or arbitrary local system OK? | | Smallest feature | What is the minimum object size to capture (affects resolution)? | | Area size | Approximate square metres and number of floors | | Timeline | Scan date and delivery turnaround (typically 3–5 working days) | | Deliverables | Point cloud format, CAD level of detail, BIM LOD required |

Getting these right upfront avoids costly re-scans and ensures the provider uses the right scanner for your project.

SLAM Scanner Comparison: BLK2GO vs GeoSLAM

Choosing the right scanner is critical. Here is how the main handheld SLAM options compare:

| Feature | Leica BLK2GO | GeoSLAM ZEB Go | GeoSLAM ZEB Horizon | | --- | --- | --- | --- | | Accuracy | ±20mm (±6–15mm relative) | 10–30mm geo-matching | ±15mm | | Range | 10m | 30m | 100–120m | | Weight | 0.7kg | 2.65kg | 1.4kg | | Environment | Indoor only | Indoor/outdoor (poor GPS) | Indoor/outdoor | | Points/sec | 420K | 43K | 300K | | Best for | Rapid facility docs, site tours | First-time SLAM, education | Mixed environments, longer range | | Survey-grade? | No | Limited | Better for engineering |

Key insight: BLK2GO is ultra-portable but not survey-grade for engineering work. GeoSLAM Horizon offers better accuracy and range for construction and surveying projects. Confirm which scanner your provider will use and whether it meets your accuracy requirements.

Preparation Checklist: Pre-Scan

Site Preparation

• [ ] Site access confirmed and PPE requirements identified
• [ ] Safety equipment available (hazardous zones: asbestos, silica, ammonia)
• [ ] Scan locations planned to minimise shadows and occlusions
• [ ] Reflective targets placed (minimum 12, visible between consecutive scans)
• [ ] Lighting adjusted: soft and diffuse; avoid direct sunlight and harsh shadows
• [ ] Surfaces cleaned of dust; apply matte target dots where needed
• [ ] Furniture and obstructions moved where possible
• [ ] Floor-to-ceiling height confirmed for scanner clearance
• [ ] Site contact available on the day for access and questions
• [ ] Asbestos surveys completed if required (common in older buildings)

Information to Provide to Your Scanner

• [ ] Site address and access instructions (parking, loading)
• [ ] Scope of scan: which areas, floors, or zones
• [ ] Purpose of scan (BIM, CAD, heritage, volumetric)
• [ ] Required accuracy and tolerance
• [ ] Deliverable formats (E57, RCP, DWG, RVT)
• [ ] Coordinate system required (OS National Grid or local)
• [ ] Any areas to exclude (secure zones, residential areas)
• [ ] Known hazards (asbestos, live services, unstable structures)
• [ ] Preferred scan date and deadline for deliverables

Accuracy Specifications Explained

| Application | Typical Accuracy Required | Scanner Type | | --- | --- | --- | | Heritage preservation | ±10–20mm | Handheld SLAM | | Architectural documentation | ±10–15mm | Handheld SLAM | | Refurbishment and extension design | ±5–15mm | Handheld SLAM | | MEP coordination | ±5–10mm | Tripod scanner recommended | | Structural engineering | ±2–5mm | Terrestrial laser scanner (TLS) | | Industrial plant and process | ±1–3mm | High-precision TLS | | Volumetric analysis | ±10–50mm | Handheld or tripod |

Golden rule: If tolerances are tight (<10mm), use a tripod scanner. For most architectural and building work, handheld SLAM accuracy is sufficient.

Common Mistakes to Avoid

1. Choosing scanners based on price alone: The cheapest scanner may not meet your accuracy requirements. Always specify accuracy first, then compare providers.

2. Insufficient site preparation: Cluttered, reflective, or poorly lit sites produce poor-quality scans. Do a site walkthrough before the scan date.

3. Unclear accuracy specifications: If you do not specify accuracy requirements, you may receive data that is not suitable for your intended use.

4. Missing coordinate system requirements: If you need OS National Grid coordinates or BIM-compatible levels, confirm this before the scan. Retrofitting coordinates later is costly.

5. Not specifying minimum feature size: For MEP coordination, you need 5–10mm resolution — a standard scan may capture at 25mm resolution by default.

6. Skipping the asbestos survey: In older buildings, scanning disturbed asbestos is a serious health risk. Complete an asbestos survey first.

7. Accepting point cloud without QA: Always request a sample of the registered point cloud before full processing. Check for gaps, noise, and misalignments.

8. Unclear deliverables specification: Be specific about file formats, naming conventions, coordinate systems, and BIM LOD. Ambiguous briefs lead to re-work.

What to Expect on Scan Day

1. Arrival and setup: Scanner setup, control targets placement, site walkthrough (30–60 minutes depending on site size)
2. Scanning: Walk-through scanning of all specified areas (time varies by size and complexity)
3. QC check: On-site registration quality check to identify any gaps needing re-scanning
4. Departure: Data backed up and site left as found

Most small-to-medium sites are scanned in a single day. Larger or complex sites may require multiple visits.

Deliverables Checklist

Agree these deliverables in writing before instruction:

• [ ] Registered point cloud (E57, RCP, LAS, PTS — specify your format)
• [ ] Coordinate system and georeferencing (OS National Grid, local, or arbitrary)
• [ ] 2D CAD drawings if required (floor plans, elevations, sections — DWG and PDF)
• [ ] 3D BIM model if required (Revit RVT — specify LOD: 100, 200, 300, 350, or 500)
• [ ] IFC and COBie export if required for asset management
• [ ] Scan-to-BIM modelling scope and level of detail agreed in writing
• [ ] TruView or equivalent online viewing portal (for client review)
• [ ] QA report confirming registration accuracy and coverage completeness
• [ ] Native scan data archived (in case of future re-processing needs)

Frequently Asked Questions

Q: Can handheld 3D scanning replace a measured building survey?

For many applications, yes. Handheld 3D scanning with registered point cloud output is increasingly accepted by planning authorities and design teams. However, if you specifically need floor areas, ceiling heights, and room schedules in CAD or BIM format, a measured building survey may be more cost-effective. Discuss your requirements with your provider.

Q: How accurate is handheld 3D scanning?

Handheld SLAM scanners typically achieve ±5–20mm accuracy depending on the hardware, environment, and scanning methodology. For engineering tolerances under 10mm, a terrestrial tripod scanner is recommended.

Q: Can handheld scanning be used outdoors?

GeoSLAM ZEB Horizon and similar outdoor-capable SLAM scanners work in outdoor environments but are less accurate than indoor scans due to GPS limitations and environmental factors. For large outdoor sites, a combination of SLAM scanning and GNSS surveying is typically used.

Q: How do I prepare my site for a handheld 3D scan?

See the Site Preparation checklist above. Key actions: declutter spaces, ensure lighting is adequate, complete any hazardous materials surveys, and have a site contact available on the day.

Q: What is the difference between scan-to-BIM and point cloud-to-BIM?

Scan-to-BIM means the scanning provider also produces the BIM model from the scan data. Point cloud-to-BIM means you receive the raw point cloud and commission a separate BIM modelling team to create the model. Scan-to-BIM is typically faster and involves one point of responsibility; point cloud-to-BIM allows you to use specialist BIM modelers.