Clipping from a polygon

[Edwin Humphries]

Hi all,

I'm working on mapping vegetation communities on a property on the outskirts of Sydney.

Currently, the mapped vegetation communities include areas where there are buildings, car parks, and roadways, which need to be excised from the vegetation community polygons.

The Clipper plugin (by Giuseppe De Marco) works really well when the area to be excised lies wholly within a single polygon. However, some of these features cross vegetation community boundaries, and in that scenario, the plugin doesn't seem to do anything.

So, when, for example, a roadway crosses several vegetation communities, is there an easy way to excise the polygon that defines the roadway from the vegetation polygon?

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Regards and thanks in advance,
Edwin Humphries
Mobile: 0435 672 457

I acknowledge the traditional Wodi Wodi custodians, their elders and customs, of the Dharawal lands on which I live.

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[Andrew Jeffrey]

Hi Edwin,

If I understand correctly you want to remove the road corridors from the vegetation layer? 

I in that case, I don’t think you want to clip. I think you are after the difference tool in the processing tools. It provides a result which is the difference between the two layers e.g. areas that are not common to both.

I think I supplied screenshots to the process in your previous clipping question if you’re interested in exploring this tool.

Thanks

Andrew

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[Chris Kahler]

Hi Edwin,

I have mapped a lot of vegetation. My tip is to construct your mapping as lines and point then convert these to polygons.

It sounds like extra work but this methods avoids a lot of problems, such as the ones you’re encountering, later on in the process.

All the best.

CK

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