Height Data - collection methods
- LiDAR (Light Detection and Ranging):
This technique measures distances using Laser Technology and is based on measuring how long it takes for a light wave to travel from an airbourne location, usually an aeroplane, to bounce off the object and come back. By dividing the time by two (to measure the distance one-way instead of the round trip), and multiplying the result by the speed of the light wave, a height value is therefore obtained. It is the predominant data collection method used today.
- IFSAR (Interferometric Synthetic Aperture Radar):
This technique works on the same principle as LiDAR except using radio waves instead of light waves. Notably used by Intermap in production of the NEXTMap Britain Dataset.
- Photogrammetry
This is the practice of obtaining information, about physical objects, including height values, through the process of recording, measuring and interpreting photographic images.
- Topographical Survey
GPS Survey and in the past, surveys measured to the national benchmark network, have been included in some datasets. However, due to the high cost of collecting data in this way, survey data has not been widely used to collect and produce commercially available datasets and is primarily used to verify other capture methods.
NB. Laser Surveys Ltd is the parent company of Centremaps. Established for over 30 years, it is one of the longest established survey companies' in the UK. It is able to offer a full range of pre-contract mapping services including Topographical and Measured Building Surveys. For more information visit www.lasersurveys.com .