Energy Rail Resources (ERR), one of the biggest hard coking coal producers and exporters in Mongolia, was tasked to implement a railway development project in the Mongolian steppes. They asked Airbus Defence and Space to create an accurate topographic map compliant with the standard 1:5,000 scale including the drawing of 2m contour lines. Accurate Ground Control Points (GCPs) were needed to meet the customer’s specifications, but sending out a GPS surveyor to collect them in-the-field in Mongolia would not have been effective – neither in terms of costs nor time.
Creating 1:5,000 Topographic Maps in Mongolia using our Satellite Constellation
Solution & Results
To optimize costs for the company, Airbus Defence and Space provided GCPs featuring a better than 1m CE90 accuracy extracted from TerraSAR-X imagery. The high-resolution SAR satellite is ideally suited thanks to a strong stability on its orbit and a very precise native accuracy. Pléiades stereo pairs were collected over the area within a period of just 4 weeks. The bundle adjustment of these stereo pairs was based on TerraSAR-X Ground Control Points. Technically, matching radar GCPs with optical imagery is not always straightforward, as an element that can be seen on a radar image may not be visible on optical imagery and vice-versa. However, Airbus Defence and Space has built a strong expertise in this area and this is now a mastered process that has been successfully used for many projects, especially over difficult-to-access regions. As a result, the aero-triangulation featured an accuracy of 4m CE90 horizontally and a 5m LE90 vertically.
The stereo restitution and the map creation were completed, quality controlled and the final product was delivered to the customer, on time as per specification, only two months after initial collection.
- Pléiades substantial acquisition capacity enables fast collection of input data for topographic mapping at scales of 1:5,000, without the need for complex planning and organisation of an airborne acquisition in remote, difficult-to-access locations
- Pléiades stereo pairs’ quality is praised and recognised by the market as an industry-leading input for 3D product creation
- TerraSAR-X is a truly global and fast solution for accurate Ground Control Points
- Airbus Defence and Space’s know-how and expertise allow mixing of the very best of each sensor to create topographic maps that are cost-effective, timely and high-quality
Any challenging infrastructure project (e.g. dam settlement, pipeline implementation, road engineering, bridge construction etc.) requires state-of-the-art topographic mapping, especially in remote locations where GPS surveys are difficult or impossible to carry out. Bundle adjustment of Pléiades stereo pairs with TerraSAR-X Ground Control Points is a valuable solution for on-spec and high-quality map creation, thus reducing time, risk and investment compared to alternative solutions.