Boundaries – Drone Surveys
CGD Ltd has recently purchased a drone to support its boundary investigations work. The drone provides a number of benefits to us.
- Provides a unique perspective of a boundary
- Using specialist software we are able to make accurate measurements.
- The drone captures photos which contain a huge amount of data
- The photos provide a unique and permenant record
- Drone takes vertical and oblique photographs
Find out below how we use aerial photos to create maps and investigate boundaries.
Vertical Aerial Photo from Drone
Combining a number of photos to create an ‘Orthophoto’
Both vertical and oblique photographs have long been used by Surveyors in the investigation of boundary issues. These photographs, some very old, have been used as evidence to support a surveyors case. Whilst these photographs can prove very useful, they cannot be used to make measurements.
From the earliest days of manned flight, we have used photographs taken from the sky to help in map making. Techniques developed very quickly mainly due to the need for accurate maps during the 2 world wars. Soon it was discovered that, not only could you create maps from photographs taken from aeroplanes, but, by using 2 photographs taken from different locations, surveyors could actually see the world in 3 dimensions. This technique, ‘Photogrammetry’, has been used widely by Ordnance Survey to map the UK. Today, it is not necessary to be able to fly a plane to take aerial photographs, we can use drones instead.
Our use of aerial photographs differs slightly from this traditional photogrammetry. We use software to combine a number of aerial photographs into one ‘Orthophoto’.
Example of an Orthophoto
Orthophotos are a great resource. Not only can they be used to see features from the air, but they are also accurate and can be used to for measurement purposes.
Orthophoto mapped onto Ordnance Survey map
This image, which shows a recent boundary investigation using drone photographs, over Ordnance Survey mapping, does not show the full potential of these orthophotos.
Example of an Oblique Photograph
We can also use oblique photographs (non-vertical) in our investigations.
When combined with accurate ground control points (targets on the ground, seen in the photographs, and coordinated using GPS) the results are nearly as accurate as a traditional topographic survey.