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Projects: GPS Reflectivity Survey

Dec. 2015

Almost 10 years ago we were engaged by a client to produce some GPS based plots showing reflectivity of road markings.

At the time we were supplied a series of Excel spreadsheets with the GPS location and reflection value. These then had to:

  • be loaded into an AutoCAD Drawing file
  • have the points connected to produce lines
  • have the line segments updated to represent the level of reflectivity gathered by the vehicle mounted sensors
  • have the generated line overlain onto an OS MasterMap base map

The 1st challenge in this project was to transform the GPS and reflectivity of data from the Excel Spreadsheet in to a usable spatial format.  At the time the 'easiest' way to execute this was to use the annotation template capability in AutoCAD Map to create and AutoCAD block with the positional and reflectivity information.

This in turn was used to feed an export to an ESRI SHP file.

The ESRI SHP file was then imported back into AutoCAD Map but this time a projection transformation was applied so that the WGS84 based GPS data was transformed to British National Grid.

A little bit of Visual Basic programming was then deployed to compare the reflectivity value of the survey point with that of the next one.  A line was then created between the two points and coloured according to the reflectivity values.

Finally, the Ordnance Survey background mapping data was queried into the AutoCAD Map environment and then saved as a DWG file, plotted to PDF and submitted to the client.

We would handle this project differently now but back then this was considered the most efficient way to process the data.

Today we would tackle this project using the capabilities of a spatial database environment.

Give us a call for more details on 01462 816648.

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