• Which the release of FS2020 we see an explosition of activity on the forun and of course we are very happy to see this. But having all questions about FS2020 in one forum becomes a bit messy. So therefore we would like to ask you all to use the following guidelines when posting your questions:

    • Tag FS2020 specific questions with the MSFS2020 tag.
    • Questions about making 3D assets can be posted in the 3D asset design forum. Either post them in the subforum of the modelling tool you use or in the general forum if they are general.
    • Questions about aircraft design can be posted in the Aircraft design forum
    • Questions about airport design can be posted in the FS2020 airport design forum. Once airport development tools have been updated for FS2020 you can post tool speciifc questions in the subforums of those tools as well of course.
    • Questions about terrain design can be posted in the FS2020 terrain design forum.
    • Questions about SimConnect can be posted in the SimConnect forum.

    Any other question that is not specific to an aspect of development or tool can be posted in the General chat forum.

    By following these guidelines we make sure that the forums remain easy to read for everybody and also that the right people can find your post to answer it.

QGIS difference tool (quirks?)

kevinfirth

kevinfirth

Messages
203
Country
unitedkingdom
I've got a little issue with a quirk it appears in QGIS.

Ive imported my UK coastline (Ordnance Survey source, all multiple lines dissolved together, single parts joined as a multipart poly, as a shp layer, reprojected to WGS84)
I have also got a bounding polygon,(also shp layer, reprojected to WGS84)

I have tested the vector>geoprocessing>difference tool in QGIS with 3 very simple polygons so I know it can perform the task I want it to, which is to cut out from the bounding poly the coastline poly, so it essentially leaves me with a poly representing the sea around the UK. I intend then to use this in Scenproc to create my QMID11 hydropolys to be able to do accurate water masking around UK photoscenery.

However, when I use the same workflow that worled with the 3 simple polygons on the far more complex UK coastline poly, the output shp file is just the full bounding polygon again? :S

I've made sure the 2 layers have the same projection and are both shp layers, but I cant see now what might cause this not to work? Can anyone shed any additional light on why this more complex scenario isn't performing how I'd expect it to please?

Thanks Kev
 

Attachments

  • QGIS UK coastline.jpg
    QGIS UK coastline.jpg
    183 KB · Views: 488
SOLVED: It was my stupidity. The difference tool works perfectly, the problem was I was trying to use a line layer with a polygon layer which was never going to work. A simple new layer containing the line transformed to polygon worked excellently :)
 
You must log in or register to reply here.
Back
Top