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When drawing a new polygon it inverts existing parts of the polygon #14389
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Author Name: Giovanni Manghi (@gioman) can't see any attached image. It would be useful to understand better what do you mean. |
Author Name: Gerhardus Geldenhuis (@ggeldenhuis) Apologies must have missed off the image. Hope it helps to clarify what I mean.
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Author Name: Giovanni Manghi (@gioman) The overlapped part it hasn't a "reverted color" it is (it becomes) a hole. The simple features model does not allow to draw such geometries (self-overlapping), and QGIS let you know by marking those two nodes with a green "X". I agree with others that eventually allow to draw such wrong geometries it is not right. An option that can be eventually be discussed/added could be the one to make qgis refuse to add invalid geometries.
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Author Name: Gerhardus Geldenhuis (@ggeldenhuis) I should have been clearer. The screenshot is in mid-edit so the edit is not finished. I would certainly agree that you should not be allowed to make "wrong" geometries. What I am suggesting is that when you are digitizing a complex shape it would be useful when you overlap the existing polygon to not become a "hole" but rather double in colour density. That would be more intuitive. I am not suggesting the ability to draw wrong shapes but suggesting a more intuitive way for the polygon "shadow" or whatever the correct terminology is to behave in a more real life physical way. I equate the to folding a piece of semi transparent film over it self, it will darken in colour every time you fold it. |
Author Name: Giovanni Manghi (@gioman) Gerhardus Geldenhuis wrote:
ok, now is clearer, but the doubt remains, why do so if at the end that area will become an hole anyway? |
Author Name: Gerhardus Geldenhuis (@ggeldenhuis) I will explain with an example the first image is midway through editing and the second image is the result. It is per illustration only. However I realize while creating these images that there is a logic problem... I don't think what I am asking is doable anyway... I am expecting the computer to know what I want to do and it can't possibly do that...
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Author Name: Giovanni Manghi (@gioman) Gerhardus Geldenhuis wrote:
I understand your point, but as you say, what the program can do for it? Any evidence that other sw packages (gvsig, udig, kosmo, etc.) do work in a way that can be considered better than the qgis way? |
Author Name: Gerhardus Geldenhuis (@ggeldenhuis) I have not used any of the other software packages mentioned so would unfortunetly have no idea. On the whole so far I have really liked the experience in QGIS |
Author Name: Giovanni Manghi (@gioman) Gerhardus Geldenhuis wrote:
at the next developer meeting I will try to have a chat with the devs about this matters (in general how overlapping polygons are handled). |
Author Name: Giovanni Manghi (@gioman)
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Author Name: Paolo Cavallini (@pcav)
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Author Name: Paolo Cavallini (@pcav)
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Author Name: Jürgen Fischer (@jef-n)
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Author Name: Giovanni Manghi (@gioman)
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Author Name: Gerhardus Geldenhuis (@ggeldenhuis)
Original Redmine Issue: 4462
Affected QGIS version: master
Redmine category:digitising
When you draw a new polygon it inverts already drawn parts of the polygon back to the layer underneath. I would have expected an doubling in colour or half the transparency of the red layer of the polygon. The encircled area in the attached image should be a darker colour rather than inverted.
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