Geographic Information Systems Stack Exchange is a question and answer site for cartographers, geographers and GIS professionals. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I am doing some work on sight distances and I need a map or whatever of the UK that contains roadside features (road signs, trees etc) as well as the road features (road centreline, etc) so I can convert to an appropriate format for use in ArcGIS. I will need to eventually write a programme such that based on the required sight distance I can create a line that will intersect with these roadside features and know if they obstruct visibility.

So first I need a map of the UK which shows these features such that they can be understood by ArcGIS. If anyone knows anything please let me know.

share|improve this question
Free - OpenData Vector Map District… - At Cost OS MasterMap… – Mapperz Apr 12 '11 at 14:00
sur555 you state 'UK' (this includes Northern Ireland) Ordnance Survey only has data covering Great Britain (England, Wales and Scotland). – Mapperz Apr 12 '11 at 14:18
Many thanks for your suggestions so far. I actually need it for the east midlands, UK at this point in time. surv555 – surv555 Apr 12 '11 at 14:30

Your choice of data and the viability of any other options depends hugely on the scale of your calculations.

Mapperz provides a couple of great links. However, you will have to add your own heights to features from these data as certainly the OS does not provide any information on the third dimension. That's fine for many of the small features you mention such as road signs as most of them are standard.

For trees and buildings you have more of a problem. However, if your area is small then you can try deriving building and tree heights using something like NextMap's LIDAR-derived DSM data (available from EMapSite for instance). It can get expensive for a good resolution though. Again for large stands of trees, you can try to obtain forestry records. This latter approach won't help you for individual urban trees though.

If your visibility calculation is really so detailed that individual road signs are critical, this suggests that you are working on a very small area, in which case it might even be more cost effective to invest in a cheap hipsometer and send a student on work-experience out to measure the features and record their locations with a GPS while you're at it.

Bear in mind though that there is not much point having hugely detailed and expensive information on the heights and widths of tiny objects like road signs (tiny in landscape terms) if you are using the OS 50m resolution Panorama height data. The free Panorama data contains many errors beyond those stated by OS. These include spikes and pits but also tiling artefacts such as trenches and ridges. On top of that, at 50m, sharp features tend to be smoothed. This doesn't matter if you are doing landscape scale visibility calculations over several kilometers but will matter if you are doing visibility calculations where an individual road sign must be accounted for. So, on top of your 3D features data you must also consider the resolution of your terrain data carefully. For your use-case, perhaps the OS 10m resolution data is not fine grained enough even?

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.