Laser data

The simplest definition of laser data is 'a collection of X,Y,Z points'. The most basic explanation of airborne laser measurements is a point cloud describing the earth's surface and everything that is built on it, as shown in the upper figure.

However, modern airborne laser scanners offer more observables which can help us to learn more about the objects we measure.

First of all, our systems deliver multiple returns, so we not only measure the last pulse that returns, but also the first, and, in some systems, up to three other pulses. The systems also deliver the intensity of every pulse as an additional observable. Integrated with our digital cameras each laser pulse also has a RGB-value (colour) attached to it.

The last pulse is used to derive the digital terrain model, meaning the bare earth without obstacles like trees, houses, cars etc. By adding the first pulse the digital elevation model can be computed; including all additional objects that are situated on the earth.

The difference between the first and last pulses can be used to compute a model of objects on the earth's surface such as a model of the tree canopy, for example.

Adding the intensity data gives us an observable that makes it possible to further classify the objects we measure based on their reflectance. The second figure shows a good example of this. When we add the RGB-value – the colour – to our basic Lidar observable, this results in 3D images, allowing further automated classification of the objects measured. It gives us a real 3D mapping tool.

At TerraImaging we use special software tools to generate the basic Lidar products, the DTM and DEM efficiently and at a high quality level. In addition, we have developed sophisticated tools to expand these basic products with a classification of the type and properties of the objects measured: buildings, water, roads, railroads etc.

TerraImaging can advise you about the best Lidar data-acquisition for your project and perform the job at high quality standards. Already acquired your data? Let us advise you how to get more information from your data and allow your data sets to bring you more revenue.