LiDAR Acquisition

Accurately model complex environments and physical objects

Just as cameras allow us to see objects in pictures, a LiDAR instrument allows us to visualise objects in three dimensions. A LiDAR system can be carried on an aircraft to look down on the ground or moved around at ground level to draw objects around it. It can also be used on a road vehicle. Large areas can be covered quickly using these mobile lidar mapping techniques.

LiDAR image of the Thames river in London

At the heart of a LiDAR system is a laser ranger. The laser is made to send out a small pulse of light and then to receive the reflected pulse, once it has hit an object. The time measured between the pulse being sent and subsequently received can then be equated to the distance travelled by the pulse, because the speed of light is constant.

To produce a three dimensional model of an area, the laser is scanned across and along the area of interest and many pulses are used to produce point distances on the ground, from the laser. The angle of the laser and its position is recorded for each laser pulse it sends out and thus a three dimensional image can be produced by combining the point distances relative to each other in a computer program. The closer the points are on the ground, the more accurate the model.

Modern LiDAR systems can produce hundreds of thousands of pulses every second and can be flown several thousands of feet above the earth. This allows for extremely rapid acquisition of data over large areas, which may be hostile or inaccessible from the ground using previous methods of surveying.

Airborne LiDAR

Peat analysis on behalf of National Trust

When fitted to an aircraft, the system is flown over an area along overlapping strips until the complete area of interest is covered by the laser points.

The use of high accuracy GPS positioning and inertial attitude measuring instruments, together with powerful computing software allow very accurate models to be produced. The picture above shows colour contour map type data of the River Thames.

LiDAR Applications

Applications for the use of LiDAR are evolving, but generally any application that requires a volumetric or three dimensional set of data can be considered. Below are just a few examples of how LiDAR data is used currently.

Urban planning
Floodplain mapping
Coal stock monitoring
Quarry extraction monitoring
Road/rail planning
Coastal erosion monitoring
Telecommunication cell network planning

LiDAR Products

Data from the LiDAR can be used in a variety of ways:

Computer file containing XYZ data (position and height)
Hard copy print of colour contour map
3D representation on a computer, allowing rotation and ‘fly-throughs’
Physical scale models

We operate a fleet of aircraft equipped with our suite of digital sensors – available for international as well as UK project data acquisition, with a dedicated production facility.

Equipment & Instrumentation

Our suite of instruments includes:

A Leica RC20/30 full format film camera
An Optech GEMINI LIDAR system integrated with a Rollei digital camera
An Optech ALTM 2033 LIDAR system
A Leica ADS40 camera
A Vexcel UCX large format digital camera
A Specim AISA Eagle multi-spectral line scanner
A Track Air MIDAS oblique photography system

We have a team of experienced aerial survey systems operators, engineers and planners, able to plan and acquire data to the exact requirements of the client. Aerial photography and airborne LiDAR data are extensively used as an essential building block for any successful geo-information project. We can supply imagery in RGB and infra-red (CIR) format, from our state of the art sensors and use these as the basis of bespoke topographic surveys. LiDAR data can also be acquired in multiple resolutions up to 12 points per metre to support estuary surveys, flood modelling, DTM generation, 3D building construction, pipeline route selection and Wind Farm site selection and development to name but a few.

LiDAR

Did you know?

Aerial photography, height data, flood models and mapping is available off the shelf from the GeoStore website