Two Technologies, Very Different Strengths
We operate both LiDAR and photogrammetry systems across our fleet, and the question we get asked more than any other is: which one do I need? The honest answer is that it depends entirely on your site conditions and what you plan to do with the data. I’ll break down the practical differences based on what we’ve seen across hundreds of projects in Ireland.
What Each Technology Actually Does
LiDAR (Light Detection and Ranging)
A LiDAR sensor mounted on the drone fires millions of laser pulses per second at the ground below. Each pulse bounces back, and the sensor measures the return time to calculate the exact distance. The result is a dense point cloud – millions of 3D points representing every surface the laser hits. Our DJI M300 with the Zenmuse L2 captures over 240,000 points per second, producing datasets with 200+ points per square metre.
The key advantage: LiDAR pulses can pass through gaps in vegetation to reach the ground beneath. If your site has tree cover, scrub, or dense undergrowth, LiDAR is often the only way to get accurate ground levels without clearing the vegetation first. We’ve written a detailed piece on LiDAR for vegetation penetration if this is relevant to your project.
Photogrammetry
Photogrammetry uses overlapping aerial photographs – typically captured with a high-resolution camera on the drone – and specialised software to reconstruct a 3D model of the site. The software identifies common points across hundreds or thousands of images and triangulates their positions in 3D space.
The result is a detailed orthomosaic map, a digital surface model, and optionally a textured 3D model of the site. The data is accurate to ±5cm with proper ground control, and you get the added benefit of a visual record – every pixel is a real photograph, so you can see exactly what the site looked like at the time of the survey.
When to Choose LiDAR
From our experience on Irish sites, LiDAR is the right choice when:
- The site has significant vegetation cover. Forestry surveys, overgrown brownfield sites, woodland assessments, and sites where you need bare-earth ground levels under tree canopy. Photogrammetry will model the top of the trees, not the ground.
- You need a bare-earth DTM for flood risk or drainage design. LiDAR strips away vegetation in processing to produce a clean ground model – exactly what hydrological engineers need.
- The project involves corridor surveys – power lines, road corridors, pipeline routes – where you need ground levels and obstacle heights along a linear path.
- You’re working with dense point cloud data in Civil 3D or similar. LiDAR point clouds import cleanly and classify well for engineering design work.
When to Choose Photogrammetry
Photogrammetry is the better option when:
- The site is open with minimal vegetation. Construction sites, quarries, open farmland, urban areas – anywhere the camera has a clear view of the ground.
- You need a visual record. Construction progress monitoring, planning applications, insurance documentation, and stakeholder reporting all benefit from the photographic output.
- Budget is a primary concern. Photogrammetry surveys cost less than LiDAR because the sensors and processing are less expensive. For projects where both technologies would achieve the required accuracy, photogrammetry is the more economical choice. See our drone survey cost guide for typical pricing.
- You need stockpile volumes or cut-and-fill calculations. On open sites, photogrammetry delivers volumetric accuracy within 1-2% – more than sufficient for most commercial applications.
Can You Use Both?
Yes, and we do this regularly. On larger or more complex projects, we’ll fly LiDAR and photogrammetry on the same visit. The LiDAR gives us accurate ground levels even under vegetation, while the photogrammetry provides the visual orthomosaic and textured 3D model. The two datasets overlay perfectly when captured with the same RTK/PPK positioning, giving the client the best of both worlds.
We’ve documented a real example of this approach in our combined LiDAR and photogrammetry case study. For a deeper technical comparison, our pillar guide on LiDAR vs photogrammetry covers the accuracy specs, deliverables, and pricing in more detail.
The Quick Decision Guide
If you’re not sure which technology your project needs, here’s the simplest way to think about it:
- Trees or vegetation on site? → LiDAR
- Open site, need visual record? → Photogrammetry
- Engineering design data needed? → LiDAR (or both)
- Budget-conscious, open site? → Photogrammetry
- Not sure? → Send us the site location and we’ll recommend the right approach
We carry both systems on every site visit where there’s any ambiguity. If we arrive and conditions suggest the other technology would serve you better, we can switch on the spot. That flexibility is one of the advantages of working with an operator who runs both platforms daily rather than specialising in just one.