Frequently Asked Questions

Please note, this page will be updated throughtout the consultation period.

How will Natural England use the viewshed data?

Natural England have yet to determine exactly how they will use this information but this will be guided by their review of the data and particularly by your consultation comments. Broadly speaking, the intention is that NE will then look at their existing system of buffers around protected landscapes and see how they might be modified using this new information.

I cannot get the files to load correctly, what do I do?

Contact GeoData Institute on viewshed@geodata.soton.ac.uk or call 02380 592719.

Why are you asking for geographically tagged comments?

Rather than spending large amounts of time reviewing comments and making edits to the map, we are proposing to collate comments so that it can be used as an additional layer of information based on expert local knowledge.

The PDF map is not detailed enough for me to see the areas I am interested in. Is it possible to get a higher resolution version?

The PDF option is a trade off between being able to provide a single light weight file to users but which sacrifices some of the detail they can see. Sub-setting the areas was also an option to provide several more detailed maps for parts of a protected area but would have meant we would have had many more files to collate - we are processing and collating comments on c100 protected areas. However, if you are able to download large files please contact us and we can potentially send a higher resolution version.

Why are buildings and trees excluded from the modelling?

The original intention was to run the analysis both with and without surface features (buildings and trees). However, only the DTM was available under NE's current licensing arrangements, so the analysis is based on a 'Bare Earth' model.

There appears to be a gap in my map?

This may be due to a gap in the input data coverage. A known example is the North end of the Offas Dyke Way, where no DTM was available.

There appear to be strange artefacts in the data

This is a known issue and relates to the merging of the individual viewsheds which are effectively radii around the observer point - hence why many artefacts are arc shaped . When the individual viewsheds are merged, the minimum Height at which Objects would Become Visible is used in the areas of overlap and we believe this is causing these 'patterns'. However, this is what we would expect the model to do. Other artefacts (typically horizontal lines) in the vector data are a result of the raster to vector conversion.

Why is the consultation not using an online mapping tool?

Due to the limited budget available to develop the models and tight timescale to facilitate this consultation, there was not time to develop a web-based system. Web based tools also do not allow users the flexibility to put the datasets into their own GIS systems. Therefore, we opted to provide a range of data formats instead.

Can I receive the data in another GIS format?

Potentially yes, please contact us.

Why was 20km selected as the limit of visibility?

Initially 24km was used for limit of visibility based on Hill et al's (2001) paper which states that beyond this the limit visual impact is minimal. The reduction to 20km for the limit of visibility was agreed with Natural England to reduce the processing effort and because beyond this, any new structure would be likely to be so large that NE would be asked to consult on it via other channels anyway.