Lidar Vs Photogrammetry Technologies

Lidar Vs Photogrammetry

Lidar and photogrammetry technologies are almost similar but different at the same time based on the techniques used.

Lidar is a light Detection and ranging technology that uses laser beams. Photogrammetry transforms the 2D images into 3D models.

Lidar and photogrammetry have different use cases with different conditions and deliverables. The two technologies offer fast delivery and high data density.

Difference between the Lidar and Photogrammetry technologies

Differences

Lidar

Photogrammetry

1.
Technology: Lidar uses laser beams technology to measure the time it takes for the light rays to return to the surface It uses passive technology to transform 2D images captured from the camera into 3D carto-metric models.
2. Image production Lidar uses a laser beam to make measurements of illuminated objects and Lidar returns. Photogrammetry generates points based on what is illuminated (captured images) by ambient light on the camera sensor.
3. Output It produces a 3D point cloud which depends on the sensor attributes and the flight parameters. The created datasets are difficult to interpret.

To easily understand data, a false-color based on elevation or reflection is used in visualizing the data.

In this, 2D and 3D models are generated which are easier to interpret compared to the liDAR system. The raw images produced have pixels size of below 1 cm.

It allows you to measure and view the objects in 3D output.

4.
Accuracy Lidar systems measure object distance by illuminating the object with laser light to give accurate coordinates of the object.

The 3D points of an object in space can be determined with high accuracy since the speed of light and time are constant.

It uses the same principle as the human eye to estimate the location of an object.

The technology and software used in photogrammetry give nearly as accurate as the Lidar technology.

5.
Cost Multiple hardware features are consider prior to the acquisition which is very expensive.

Dataset budgets are beyond most of the project budgets making the Lidar system very expensive to acquire.

The service prices are also very high despite the advanced of technology and development of cheaper devices.

Only a camera based drone is needed which is much cheap to acquire compared to Lidar.

Photogrammetry acquisition cost is more justifiable and cheaper.

6.
Dataset quality Lidar scanners can measure more than one point once a laser is reflected. Modeling software used can analyze data collected from certain points or filter data in groups resulting in high accuracy. This creates data points based on what is detected by the sensor camera. The object captured depends on the presence of light and camera quality.
7.
Data acquisition and processing Use survey levels of between 20-30% overlap to speed up data acquisition process.

Data processing using Lidar technology is much faster. The raw data collected require 5 to 30 minutes of calibration to generate the final output.

Uses a 60-90% image overlap to accurately process data. This depends on the hardware used and the terrain structure.

Traditional land surveying techniques used increase the processing time and cost.

More ground controls are needed to achieve near to achieve absolute accuracy.

8.
Data visualization The data points are colorized but do not give a natural output as photogrammetry. It uses RGB value for data points giving a colorized point output which is easy to understand.
9.
Uses cases When surveying narrow areas or mapping areas beyond trees, Lidar technology will be the best option for you. Used to collect visual data like in asset management, in agriculture among others.
10. Hardware cost Lidar UAV equipment is very expensive. You need to have Lidar scanners and software. You can easily buy high-performance photogrammetry equipment and start the services right away.

Conclusion

Both technologies provide you with valuable data and when choosing which technology to use, you should consider; Project use cases, environmental conditions, budgetary terms, and delivery terms.

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