If you've started researching 3D scanning options for a construction project, you've probably encountered both terms. LiDAR and photogrammetry are the two most widely used technologies for capturing spatial data on construction sites, and at first glance they seem to do the same thing: fly a drone over a site, produce a 3D model, get your data. The difference is in how they capture that data, and that distinction matters a lot depending on what your project actually needs.
How Each Technology Works
LiDAR (Light Detection and Ranging) is an active sensor technology. It fires laser pulses at the ground or structure and measures how long each pulse takes to return, building up a dense three-dimensional point cloud from direct physical measurement. It doesn't rely on ambient light or visual contrast between surfaces — it generates its own signal and reads the return. Terrestrial laser scanning in buildings uses the same underlying principle, with the scanner positioned on a tripod inside the space rather than mounted on a drone.
Photogrammetry takes a different approach. A camera captures hundreds of overlapping images of the site, and specialized software triangulates 3D coordinates from the overlap between those images — essentially reconstructing geometry from 2D photographs. The result is a textured 3D mesh or point cloud that carries rich visual information alongside the geometry.
Both methods produce usable 3D data. Where they differ is in accuracy, performance under variable conditions, and what the data is actually good for.
Where LiDAR Has the Edge
For most construction applications where precise measurement is the goal, LiDAR is the more reliable choice. Terrestrial laser scanning achieves 2 to 6mm accuracy, and drone LiDAR typically delivers 2 to 5cm vertical accuracy with proper ground control — figures that hold up in low light, on overcast days, and on sites with vegetation cover.
That last point matters more than it might seem. On civil and earthwork sites where the ground surface is partially obscured by grass, scrub, or canopy, LiDAR pulses penetrate vegetation and return ground hits from beneath the canopy. Photogrammetry captures the top of the canopy. For earthwork volume calculations where you need the actual ground surface, LiDAR is the only drone method that reliably delivers it without first clearing the site.
LiDAR also outperforms photogrammetry on surfaces that lack visual texture — uniform concrete slabs, freshly graded aggregate, sand stockpiles. Photogrammetry needs contrast and detail in the imagery to reconstruct geometry accurately; featureless surfaces can produce noise and artifacts in the model. LiDAR has no such dependency.
For as-built documentation and Scan to BIM workflows, terrestrial laser scanning is the standard method for the same reason: it measures directly, without relying on lighting, surface texture, or image overlap quality to produce accurate geometry.
Where Photogrammetry Makes Sense
Photogrammetry's primary advantages are cost and visual output. Drone photogrammetry requires significantly less expensive equipment than drone LiDAR, which makes it a reasonable choice for projects where the accuracy threshold is more forgiving and budget is a constraint.
It also produces photorealistic textured models, which LiDAR alone does not. For progress monitoring deliverables aimed at owners and stakeholders, or for documentation where visual context matters as much as dimensional accuracy, photogrammetry produces a more immediately accessible output. Many clients find a textured 3D model easier to navigate and communicate from than a raw point
On open, well-defined sites in good lighting conditions — flat earthworks, paved surfaces, clear ground plane — photogrammetry can achieve 3 to 10cm accuracy with proper ground control, which is sufficient for many site monitoring and progress tracking applications.
The Case for Combining Both
On larger or more complex projects, LiDAR and photogrammetry can work together rather than compete. A common approach on civil construction sites is to use drone LiDAR for precise terrain modeling and volume calculations, while using photogrammetry to produce the visual site record and progress imagery. The LiDAR handles the measurement work; the photogrammetry handles the communication.
How to Choose for Your Project
The decision comes down to three questions:
How accurate do you need the data to be? If the deliverable feeds into engineering, BIM coordination, or contract payment applications, LiDAR is the appropriate tool. If it's primarily for visual documentation or general progress tracking, photogrammetry may be sufficient.
What are the site conditions? Vegetation, low light, or featureless surfaces all favor LiDAR. Open, well-lit, visually textured sites are where photogrammetry performs best.
What are you doing with the data? Point clouds for construction site surveys and Scan to BIM are LiDAR territory. Photorealistic progress models and stakeholder visualizations are where photogrammetry adds the most value.
If you're not sure which method is right for your project scope, that's a straightforward conversation to have before committing to a survey approach. Get in touch with the Darling team and we'll walk through the right methodology for your site conditions and deliverable requirements.
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