For the fourth and final part of our LiDAR blog series, we take a look at the essential LiDAR attributes used in post-processing to generate a perfectly precise 3D point cloud – a vital part of maximising the value of your data! This final piece rounds out the LiDAR capture process from initial planning to post-processing with insights from many years of practical experience.
When collecting LiDAR data, a LiDAR scanner emits pulses that reflect off the surfaces below. The returns are used to give a distance measurement between the reflective surfaces and the scanner. A computer uses the aircraft’s GPS coordinates, GPS time and the orientation obtained from the IMU, to give each pulse return an accurate x, y, z coordinate, creating a spatially accurate 3D point cloud. Simultaneously, the number of returns and intensity of the returns are recorded, as is additional meta-data like the scan angle and the flight path ID.
The principles of LiDAR capture showing multiple returns
Attributes are essential for efficiently post-processing and deriving value from the data, but not all LiDAR capture companies will automatically collect all attributes. Hence, it’s important to clearly specify the results you need for your project when you prepare to capture. We have created a guideline on what aspects to include called ‘Anditi Certified Data’. It provides specifications and preferred settings for the key attributes.
Essential attributes – what you can’t go without!
Based on our learnings, here is what we recommend as ‘essential’ attributes:
In addition to the obvious x, y, and z coordinates, essential attributes include the return number (identifying the first, second, third, etc, returns reflected back from surfaces below), and the total number of returns (up to five per pulse). Flight path ID, GPS time and scan angle are all also essential to ensure that your data can be processed and utilised effectively.
The more attributes you have, the more information you have, and the more insights you can extract from your data!
So there you have it, our key LiDAR tips and tricks all the way from planning to post-processing. If you have any questions about us or our technology or want to find out more about the Anditi Certified Data guidelines, don’t hesitate to call us! We’re always happy to talk spatial data and analytics.