Lidar vs Photogrammetry: - What You May Need to Know?

Did you know there are different types of drone surveying?  Drone survey missions are largely carried based on lidar and photogrammetry technologies depending on the exact application. It is vital to consider operational factors, such as cost and project complexity.

Wondering which technology is better for your survey project:  LiDAR or photogrammetry? In this article, we will provide you a closer look at both technologies to understand how to best leverage them.

What is LiDAR (Light Detection and Ranging)?

A technology originated as a mix of “light” and “radar”. It is a surveying and remote sensing methodology that sends out laser pulses to calculate measurements and distance of buildings & landscapes.

How does it work?

LiDAR uses infrared light, and the sensors can be installed on drones, planes, automobiles, and tripods. It uses oscillating mirrors to emit laser pulses in many directions surrounding the object to generate a “sheet” of light as the drone moves forward. Through evaluating the timing and intensity of the returning pulses, it provides readings of the terrain and points on the ground.

It provides absolute accuracy of data for objects such as grounds, buildings, and roadways regardless of the larger distance using the velocity of the light pulses.

What is Photogrammetry?

It is a technique of measuring distances using images. The photographs are processed using advanced software to produce precise and realistic models of the object. The total number of pictures needed for effective photogrammetry can range from 100s to 1000s. It all depends on the size of the project site & the depth and expected outcome.

How does it work?

Drone captures many high-resolution pictures over a specified area. These photos overlap in such a manner that a similar point on the ground is visible in numerous images to form various vantage points. This technology uses different vantage points to produce a 3D map.

It generates a high-resolution 3D reconstruction with information including elevation/height, texture, color, and shape for each point on the map. This enables the easy representation of the resulting 3D point cloud. Drone system using photogrammetry provides unmatched flexibility while capturing 2D and 3D data.

Comparison of LiDAR & Photogrammetry on various parameters

1. Field of View (FOV)

Lidar: 90°
Photogrammetry: 60°

2. Image Overlapping

Lidar: Needs little to no overlap of images
Photogrammetry: Needs high percentage of image overlap

3. Surface Usage

Lidar: Scans any type of surface including homogenous textures such as grass fields, sand beaches, and more
Photogrammetry: It needs texture variation to correlate different pictures from various points of view to construct a 3D point

4. Cost

Lidar: High
Photogrammetry: Low

5. Color Detection

Lidar: Provides colorization based on intensity or elevation. It manages both natural and man-made features accurately
Photogrammetry: Generates full-color 3D and 2D models (in the various light spectrum) of the terrain which is easier to visualize and interpret than LiDAR

6. Sensor

Lidar: Present
Photogrammetry: Not Applicable

7. Input Data

Lidar:Point Cloud
Photogrammetry: Images

8. Applications

Lidar:

• Mapping terrain under the canopy
• 3D modeling of power lines or cables surveys
• Forestry, and agriculture mapping

Photogrammetry:

• Terrain modeling/mapping of open areas – mines, transport corridors, quarries,
• Broad coverage huge acre surveys with high horizontal & vertical accuracy requirements

Conclusion

We hope this article provided you a basic understanding of LiDAR and Photogrammetry technologies for drone surveying. It depends on your project requirement to choose between the two. If you’re looking for precise point cloud to 3D model conversion, connect with professional engineering design services providers. They can assist you in selecting the right process and technologies after assessing your project requirements.