Preview on Map
To help with the initial visual evaluation of geographical data at data.gov.uk, the UK Location Programme is testing a beta preview on map tool that is expected to provide a richer, more advanced way of assessing location data than metadata alone. For all location data for which a preview is available a link is provided to the preview on map tool. We welcome feedback on the tool and contact details are given below.
Start a quick search for location data to preview here.
Overview of Preview on Map functionality
The following section provides a high level overview of preview on map functionality which is described in further depth within the preview on map User Guide.
When the preview on map tool is launched it will call the view services directly from data publishers.
When the preview on map tool opens, it will display backdrop mapping as default.
You will need to select the layers you wish to view from the list of view services that you have selected to preview.
Both the map layers window, legends and information box can be collapsed using the double arrows to give a larger viewing area.
The more data sets you select to preview, the longer it will take for the data to load from the data publisher view service.
Points to note when using Preview on Map
- Consequences of connecting directly to view services
Panning and zooming will cause the evaluation window to send requests to all selected view services and the images will build on the screen in the order in which they are returned. This can cause the viewable image to change (especially if opaque images are being served by one or more view service).
- Use of an agreed coordinate reference system
Some view services may not yet support coordinates in the European Terrestrial Reference System (ETRS89) which all INSPIRE compliant view services support. If this is the case an error message will be displayed. The Preview on Map tool enables data sets to be displayed in different coordinate reference systems to different degrees of accuracy.
- Comparison of different layers
If you cannot see a layer, unchecking and re-checking it will re-send the request to the server and the layer will be brought to the front, selecting layers in a different order may assist in making a comparison.
- No common scale ranges applied to view services
Different data sets will have different ranges of scales at which they can be viewed. The data publisher decides the scale range appropriate for displaying each of their data layers through their view service. Consequently you may only be able to evaluate two layers at certain zoom levels and some may not be viewable together in the same zoom level.
- Different view services covering different geographic areas
Data layers may not overlap. Although two data layers might fall within your results of a map based search, they may not cover the same geographic area. Data layers that include the area of interest you have specified may cover a much larger geographic area. Consequently there may not be any data within your specific area of interest.
- Internet Explorer 6, 7 and 8 support for administrative areas
Internet Explorer 6-8 have a different method for drawing vector shapes in web pages from other web browsers. Internet Explorer in these editions is slower than the method used by more recent editions of web browsers. To reduce this problem we have introduced a more generalised set of administrative areas which will be displayed in Internet Explorer 6-8. Please be aware that it can still take up to 10 seconds to display administrative areas in these browsers. The map component will automatically adopt the faster drawing method if the browser supports it and will display a more defined set of administrative boundaries.
We welcome feedback on the beta version of the Preview on Map tool. As you would expect we are already working on the next version. Your comments and suggestions will be fed in to help us improve the tool.
The UK Location Programme team can be contacted thorough the UK Location Helpdesk.