In this edition of eMap’s Term of the Month, we would like to introduce a new version of airborne LiDAR and explain how its development will have a significant impact on airborne LiDAR going forward.
After nearly 20 years of ‘conventional airborne LiDAR’ a new technology is being introduced – Geiger LiDAR. A major breakthrough in collection and processing methods has been made, which means more detailed, higher resolution product deliverables in less time than ever before.
With traditional LiDAR collection instruments an aircraft flies at relatively slow speed and low altitude while pulsing a single laser at the ground. This laser hits the Earth’s surface then bounces back to the plane at different rates, which produces an image of the land being surveyed. Major drawbacks with this type of LiDAR collection is that the single laser has a very hard time penetrating foliage, only covers a relatively small patch of the Earth in any given pass, and has a lower resolution resulting in a fairly expensive collection process.
Geiger-mode LiDAR, on the other hand, can generate a denser image at a lower cost and quicker timeframe. This is accomplished by first flying at higher speeds and higher altitudes. Another major difference is the laser design itself. In Geiger-mode each laser pulse is split into 100 smaller beams, which enables them to hit multiple areas of a given target. On the back-scatter (or receiving end) these pulses are able to produce a much denser image of the area being captured, while at the same time better penetrating holes in vegetation and fog/clouds more easily.
Another difference between traditional and Geiger-mode LiDAR collection is the path in which each laser takes during the collection window. Traditional collection takes one laser and zig-zags that beam across the ground. Geiger collection focuses its laser beam in circular fashion which continually rotates while the plane flies forward. This allows the laser to hit a target from every direction instead of just one or two sides, thus eliminating the ‘shadow’ created by large buildings or valleys in the collection area.
Geiger LiDAR is still in its infancy and development is ongoing, but we are excited to see the progress being made in airborne LiDAR collection and processing. eMap is always pleased to see the geospatial industry make moves towards better products and technologies. We will keep you informed of these advancements and look forward to providing these new geospatial technologies to our customers.