Hello, I have been doing a project to calculate mountain viewsheds, basically where a mountain summits can be seen from.
I have calculated the viewsheds and polygonized to Vector. So far so good, but then I wanted to show which mountains could be seen from the summit of other mountains I appear to have 2 problems. 1. I ran a spacial query to show how many mountains (Munros) are Within my polgonized viewshed. This returns the Munros. Unfortunately I get a different number in QGIS 1.8 to QGIS 2.0.1, I don't know which is true 2. I had saved my Viewshed originally as a shapefile with a CRS of 27700 (British National Grid), I saved a version as GeoJSON with CRS of 4326. If I run the same spacial query on this file I get a different number of Munros again. So I now have 4 different figures from what I would have expected to be identical. Is data lost when a shapefile is saved as a GeoJSON file in a different CRS? and which should I beleive 1.8 or 2.0.1 or neither? If anyone wants to test this you can download the files here: Viewshed Shapefile<https://dl.dropboxusercontent.com/u/2657852/AmBodach_shp.zip>- CRS of 27700 Viewshed GeoJSON<https://dl.dropboxusercontent.com/u/2657852/AmBodach_geojson.zip>- Converted fromthe above but with CRS of 4326 Munros Shapefile <https://dl.dropboxusercontent.com/u/2657852/Munros.zip> - CRS of 27700 Wish I had realised there was something wrong before I had calculated 200 of these. Thanks, Steven
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