February 6, 2018

Leica Geosystems' TerrainMapper: the next generation of aerial linear lidar

Leica Geosystems is on hand at this year’s International Lidar Mapping Forum in Denver to showcase its new TerrainMapper aerial lidar sensor—and the system is more than just a small step forward.

As VP for airborne lidar Anders Ekelund told SPAR 3D, “at some point in time, you come to the conclusion that you need to do something brand new and completely different. The Terrain Mapper is our next generation of linear mode lidar system.”

Leica Geosystems says the TerrainMapper is so advanced that it can perform virtually any kind of aerial data collect the user needs. Here’s why.

Better performance

The full-waveform system comes in two variants, one with an 80 MP NADIR camera, and one without. Both variants feature a design based on Leica Geosystems’ recent CityMapper lidar system, with a cylindrical shape that enables installation in the company’s stabilized mount. However, Ekelund notes, the TerrainMapper system has “materially improved capacity” over its sibling.

It features an increased pulse repetition frequency of 2 MHz, handles up to 35 pulses simultaneously, and supports a wide variety of flying altitudes—from 300 meters to 5,000 meters. Leica Geosystems has also made improvements to the system’s sensitivity, promising 5 cm accuracy even at higher altitudes.

Ekelund was careful to mention that the sensor offers scan speeds of up to 7500 RPM, or 250 scan lines per second, which enables good point distribution over a “broad range of altitudes and aircraft speeds.” He also pointed out that, in addition to RGB colorization, the TerrainMapper offers colorization with elevation, intensity, RGB, CIR, and NDVI data.

Cylindrical design

A benefit of the cylindrical design the TerrainMapper borrows from the CityMapper is a circular scan pattern.

“That gives the benefit that you have both forward and backward scans,” explains Ekelund. “You always have two angles of incidence for the lidar, covering sides of buildings and providing fewer shadows in the data.” Furthermore, the pattern allows users to adjust the sensor’s field of view between 20 and 40 degrees. This enables users to reduce the size of their capture swath in order to gather higher point density when flying at higher altitudes.

In the past, such scanning patterns have returned denser results at the edges than in the center. Leica Geosystems has developed the sensor to eliminate this problem, and offer even density across the scan field.

Higher efficiency and greater flexibility

To recap, the TerrainMapper offers a higher pulse rate, variable FOV, support for a wider range of flying altitudes, higher accuracy, greater density, and variable scan speeds. These upgraded specs enable the TerrainMapper to offer a number of operational benefits compared with the “previous generation” of airborne lidar sensors.

For one, the TerrainMapper captures USGS quality level 0 data, with 8 points per square meter, at up to 2000 meters flying altitude. Ekelund explains that the sensor can capture data of this quality while covering 500 square kilometers every hour.

Click through below to view data screenshots. Metadata in file names.

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