The SnakeGrid family of products, developed by UCL Business PLC, provides a comprehensive solution to a significant problem in engineering surveying – the design of a coordinate system with minimal scale factor and height distortion even when projects extend for many hundreds of kilometres.
Who
The SnakeGrid technology was developed by Dr. Jonathan Iliffe of UCL for Network Rail. It is licensed to a number of organisations (e.g. Trimble, Leica) for use in survey instruments.
UCL also partner with specialist organisation (for example dhp11) to jointly develop products for niche markets.
What
SnakeGrid is two things:
- A set of parameters (a.k.a. ".dat file") specific to a linear project, i.e. a road or a railway.
- An algorithm that uses the parameters in the .dat file to transform between lat/lon and the specific project grid - the SnakeGrid.
Why
Map projection are either:
- Continuous with a scale factor (e.g. Ordnance Survey)
- True-scale but discontinuous (local project grid
A SnakeGrid is continuous and true-scale. The drawback is that it is only valid in a specific corridor. This corridor is "only" several tens of kilometres wide. No use for a national mapping system but ideal for a linear asset such as a railway line or road.
Within the Projection Zone mapping is continuous and linear measurements and angles are correct.
SnakeGrid Transformer
SnakeGrid Transformer is a MicroStation "add-in" jointly developed by dhp11 and UCL that is a able to transform a limited subset of MicroStation elements between SnakeGrids, OSGB and other specific grids such as the London Survey Grid and (for example) the Reading project grid.