How each method works
LiDAR, photogrammetry, and laser distance meters all produce spatial measurements, but through fundamentally different physical processes. The method determines what kind of output you get, how long it takes, and what it costs.
Direct distance measurement via laser pulses
Emits infrared laser pulses and measures the time each takes to return. Produces a dense point cloud of room geometry continuously as you move. Independent of lighting and surface texture.
3D reconstruction from overlapping photos
Captures geometry by analyzing hundreds or thousands of overlapping photographs. Software identifies matching points across images and reconstructs 3D geometry. Requires good lighting and textured surfaces.
Single-point distance measurement
Emits a laser beam and measures the time it takes to reach a surface and return. Produces one distance measurement per trigger. Requires manual recording and redraw to produce a floor plan.
Side-by-side comparison
| LiDAR (iPhone Pro) | Photogrammetry | Laser distance meter | |
|---|---|---|---|
| How it measures | Continuous laser pulse scanning | Photo analysis and 3D reconstruction | Single laser pulse per measurement |
| Accuracy | Within 1% (1 to 2 cm per wall) | 1 to 5 cm depending on setup and conditions | ±1 to 2 mm per measurement |
| Works in low light | Yes — LiDAR is independent of lighting | No — requires good lighting for photo quality | Yes |
| Floor plan output | Automatic 2D floor plan | 3D mesh or point cloud — floor plan requires post-processing | Manual only — measurements must be drawn |
| On-site time — 3-room apartment | 10 to 20 minutes | 30 to 90 minutes photo capture | 20 to 40 minutes measurement |
| Post-processing required | No — floor plan generated automatically | Yes — hours of processing in dedicated software | Yes — manual CAD redraw required |
| Total time to CAD-ready file | 10 to 20 minutes | Several hours to days | 60 to 90 minutes |
| Hardware cost | iPhone Pro (most professionals already own one) | Camera setup plus processing computer — €500 to €5,000+ | €150 to €800 |
| Software cost | From €12.49/month (Metaroom) | From €50/month (Agisoft, RealityCapture, and others) | Free to low-cost CAD program |
| Best for | Interior floor plans, building documentation, CAD/BIM workflows | Complex exterior geometry, heritage documentation, irregular surfaces | Single precise measurements, spot-checking dimensions |
Accuracy in detail
Each method has a different accuracy profile depending on what you are measuring and the conditions on-site.
A laser distance meter is the most accurate per individual measurement at ±1 to 2 mm. However, a floor plan drawn from those measurements introduces manual errors — transcription mistakes, missed angles, inaccurate sketches — that reduce the accuracy of the final document.
LiDAR scanning on iPhone Pro delivers 1 to 2 cm per wall consistently, without manual input. The floor plan reflects the actual geometry captured in the scan rather than manually recorded dimensions.
Photogrammetry accuracy varies widely by setup. Under controlled conditions with calibrated cameras and dense photo coverage, accuracy of 1 to 2 cm is achievable for interiors. In practice, with standard cameras and typical lighting, 3 to 5 cm per measurement is more realistic for interior applications. Photogrammetry performs better on complex exterior surfaces — facades, irregular structures, heritage buildings — where LiDAR range and point density are limiting factors.
Which method is right for your job?
The right method depends on what you are measuring, what output you need, and how much time and budget you have.
| Job type | Recommended method | Reason |
|---|---|---|
| Interior floor plan for renovation or CAD | LiDAR | Fastest automatic output, 1 to 2 cm accuracy, direct CAD export |
| Energy audit documentation | LiDAR | Excel and PDF export with room areas and volumes |
| As-built BIM documentation | LiDAR | IFC export ready for Revit and ArchiCAD |
| Single critical dimension check | Laser distance meter | Fastest and most precise for one measurement |
| Complex exterior facade capture | Photogrammetry | Better coverage of irregular surfaces at distance |
| Heritage building documentation | Photogrammetry or terrestrial laser scanner | Detailed surface texture capture for conservation records |
| Structural survey to millimeter precision | Terrestrial laser scanner or total station | Sub-millimeter accuracy required — LiDAR not sufficient |
For most interior documentation jobs, LiDAR scanning captures the complete floor plan in 10 to 20 minutes. For any dimension that requires millimeter precision — a niche for fitted furniture, a critical structural clearance — follow up with a laser distance meter for that specific measurement. This gives you the speed of LiDAR for the whole building and the precision of a laser meter where it matters.
Why photogrammetry is rarely used for interior floor plans
Photogrammetry works by finding matching features across overlapping photos. In plain interior spaces — white walls, uniform floors, minimal texture — there are few distinct features for the software to match. This makes photogrammetry unreliable for standard interior rooms and typically produces lower accuracy than LiDAR in these conditions.
Photogrammetry performs well outdoors, on facade surfaces with brick or stone texture, and in heritage buildings with richly detailed surfaces. For these use cases, it remains the most practical method for capturing complex geometry at scale without specialized hardware.
Frequently Asked Questions (FAQ)
Metaroom is a professional floor plan scanning app for architects, tradespeople, and energy consultants. It uses the LiDAR sensor in iPhone Pro or iPad Pro to produce a dimensioned 2D floor plan and 3D model, accurate to within 1%. Exports include DXF, IFC, RDF, PDF, Excel, and 30+ other formats. A 3-room apartment scans in 10 to 20 minutes. Scanning works in any lighting condition. Subscription from €12.49/month.
