Photogrammetry, Satellite Imagery, and LiDAR: Why Going ABOVE Requires More Than Just Images
- Clinton Bravo
- Sep 26
- 9 min read
Surveying has always been the silent backbone of progress. Before a bridge rises, before a mine opens, before a solar farm spreads its panels across rolling hills, there must first be a map that must be precise, detailed, and trustworthy. But in the Philippines, creating that map is rarely straightforward. Our landscapes aren’t gentle; they’re rugged, forested, and often difficult to access. From the mountain ridges of Benguet to the dense uplands of Mindanao and the winding coastlines of Palawan, the terrain constantly pushes surveyors to their limits.
This is where Engr. Tony (our founder) pushed his limits and contemplated what it meant to go beyond in resolving the country’s challenging terrains. He envisioned introducing a surveying technology to the Philippine market, which proved to be an effective solution to the country’s surveying difficulties. While bringing in this technology and introducing it to clients were just a part of the risks he took, the benefits of his risk-taking for this technology have continued to be realized in the Philippines until now.
For a country with thousands of islands and some of the densest canopies in Asia, relying on images alone is like trying to navigate a maze with a tourist map, you see the surface, but the real ground truths remain hidden.
That’s where the choice of technology makes or breaks a project. Photogrammetry and satellite imagery may give a bird’s-eye view, but when you’re tasked with engineering-grade accuracy, “looking from above” isn’t enough. These methods, while helpful for broad visualization, often stumble when asked to penetrate thick vegetation or capture the subtleties of slopes and drainage paths that define whether a road stands firm or crumbles in the first typhoon.
Photogrammetry, whether from drones or aircraft, relies on overlapping images stitched into 3D models. Satellite imagery paints large swaths of the earth’s surface with broad strokes. Both have their uses, but both also have clear blind spots.
For one, they mostly capture surface features. Trees, shrubs, and built structures dominate the datasets, leaving surveyors guessing about what lies beneath. In mountainous areas like the Cordillera range, this means slope stability assessments could be dangerously incomplete. In coastal areas, it could mean missing subtle grade changes critical for drainage or flood modeling.
And while photogrammetry and satellite imagery can cover vast areas (but in longer period), their accuracy usually sits at the meter level, sometimes worse depending on conditions. That may sound precise until you remember that engineering designs, runway alignments, or tailings dam embankments often demand centimeter-level reliability.
For developers, planners, and government agencies, these limitations mean delays, design revisions, and in worst cases, safety risks. It’s not that images are useless — far from it. But in the Philippines’ setting, with its dense forests, complex terrain, and climate-related challenges, they’re not enough.
Why LiDAR stands ABOVE
LiDAR doesn’t just capture an image of the surface it actively measures it. Each laser pulse sent from an aircraft or drone is timed on its return, creating millions of precise points in a single flight. These points has coordinates like northing, easting forming an accurate data. Together, they form a dense “point cloud” that represents the real shape of the ground, not just what the eye can see.
This is where LiDAR leaves photogrammetry and satellite imagery behind. Both of those methods rely on visual information: photographs stitched into models or images taken from orbit. The problem is, when you look at dense forests, tall grasslands, or even urban clutter, cameras and satellites only capture the surface of what’s visible. They cannot penetrate vegetation or distinguish between the top of a tree and the bare earth underneath. What you end up with is a digital surface model that looks good from above but fails to tell engineers or planners what lies beneath.
LiDAR, on the other hand, records multiple returns from a single laser pulse. When the beam passes through a tree canopy, one reflection might come from the leaves, another from branches, and still another from the ground itself. Each return is logged separately, allowing analysts to strip away vegetation layers and reveal the true terrain below. This ability to see both canopy and ground in one dataset makes LiDAR uniquely capable of producing accurate Digital Terrain Models (DTMs) something photogrammetry and satellite imagery alone simply cannot achieve.
For a heavily vegetated country like the Philippines, this difference is critical. In Palawan’s forest corridors or Benguet’s steep slopes, depending on images alone means missing the ground truth. With LiDAR’s multiple returns, you don’t just see the surface — you measure what actually matters for design and safety. That’s the difference between guessing where to place a mining road and knowing with engineering-grade certainty.
And accuracy isn’t a side benefit, it’s the foundation. While photogrammetry might deliver surface models with meter-level errors and satellites even coarser resolutions, LiDAR achieves vertical accuracy within a few centimeters. That’s precise enough for runway alignments at airports, dam foundations, or tunnel portals. It turns raw data into decision-ready datasets.
Criteria | Photogrammetry | Satellite Imagery | LiDAR |
How it Works | Uses overlapping aerial or drone photos stitched into 3D models | Captures images from space at varying resolutions | Emits laser pulses from aircraft/drones; records multiple returns for canopy, branches, and ground |
Vegetation Penetration | Cannot see through dense canopy; captures only surface | Blocked by vegetation and often by clouds | Multiple returns reveal both canopy and bare earth beneath |
Accuracy | Usually at meter-level; degrades in rugged terrain | Meter-level or coarser; insufficient for engineering | Centimeter-level vertical accuracy (~98% reliability in ABSD projects) |
Terrain Suitability | Works in open fields; struggles in forests and steep slopes | Good for broad regional context, but too coarse for project-level planning | Excels in rugged, vegetated, and hard-to-access terrains like Benguet, Palawan, and Mindanao |
Coverage & Speed | Requires multiple flights and heavy processing time | Covers vast areas quickly, but lacks project-level precision | Thousands of hectares covered in days; processed in weeks (ABSD completed 22,252 ha in 60 days including processing) |
Outputs | Orthophotos, surface models (limited by vegetation) | 2D images, low-resolution elevation data | High-density point clouds, DTMs, DSMs, contour maps, canopy biomass data (If a camera is used alongside the LiDAR sensor — which not all providers have — the orthophoto produced can be overlaid to the LiDAR data to reflect actual site conditions.) |
Practical Limitations | Gaps in vegetated/mountainous areas; accuracy insufficient for engineering designs | Resolution too coarse for site-specific planning; weather/cloud cover dependent | Higher cost, but delivers decision-ready datasets essential for safety-critical projects |
This table above compares photogrammetry, satellite imagery, and LiDAR across key aspects like accuracy, vegetation penetration, terrain suitability, and outputs. While photogrammetry and satellite imagery are useful for visual context, they mostly capture surface features and struggle with dense vegetation or rugged terrains. LiDAR, on the other hand, records multiple returns from each laser pulse, allowing it to reveal both canopy and bare earth with centimeter-level accuracy. For projects in the Philippines where forests, steep slopes, and flood-prone areas are common, LiDAR stands out as the only method capable of producing decision-ready datasets for engineering, planning, and safety-critical development.
Why This Matters in Philippines Geological Setting
In our setting, the value of LiDAR becomes even clearer. Think about it:
Dense vegetation makes photogrammetry nearly blind to the ground. LiDAR cuts through it.
Steep, unstable slopes make ground surveys risky. LiDAR reduces on-site exposure while still capturing every contour.
Vast project footprints (covering thousands of hectares) like wind corridors or mine concessions spanning thousands of hectares would take months to cover with traditional methods. LiDAR condenses that timeline into days of flying and weeks of processing.
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