[Qgis-user] Simple Vector-Editing Question - Deleting Multiple Rings at Once

[Nicolas Cadieux]

Hi,
Yes indeed, i has thinking at the object level. I have a method to remove thousands of rings that I developed for merging LiDAR borders files that generally results in thousands of polygones with thousands of islands.

If you want to eliminate thousands of rings, or holes inside polygons , you need create new polygon layer with a big square covering the entire area.  Then, you can subtract the polygone layer from the square.  You will be left with all the rings and the square contour.  After deleting the square contour (a single polygon), all you have left is the inside rings.  Using the merge tools, you can then merge the inside rings with polygons.  

The result is a polygon layer with no more rings.  You may have to do a spatial query to transfert the data base to the new polygons. That depends on the algorithm used. Write back if this is not clear.

Nicolas

> Le 14 sept. 2018 à 10:24, Michael Treglia <mtreglia at gmail.com> a écrit :
> 
> Hi Delaz, Nicholas,
> 
> Thanks so much for the responses!
> 
> Delaz - your solution works - not sure if it's quicker/simpler to click on the rings using the 'delete ring' tool, but it's a smart alternative option.
> 
> Nicholas - I think the challenge is that you can select the objects, but I couldn't figure out a way to select rings for a bulk deletion, as it's more about removing the holes (and selecting the bounding vertices) than selecting the objects themselves. I'm happy to learn if I was just missing something.
> 
> On a related note - for the Shape Digitizing toolbar, those tools only work to create new polygons, not new parts of a multipolygon, correct? Or is there a way to do that I've been missing? (I know you can merge tool in this case as well, but figured I'd check).
> 
> Thanks!
> Mike
> 
>> On Wed, Sep 12, 2018 at 12:12 PM Nicolas Cadieux <nicolas.cadieux at archeotec.ca> wrote:
>> Hi,
>> You have various selection tools in the GUI. (yellow box Icon with an arrow).  If you use shift + left mouse click, you can add to the current selection.  I think it is Ctlt + left mouse click in some version of QGIS.
>> Nicolas
>> 
>>> On 2018-09-12 11:12 AM, Michael Treglia wrote:
>>> Hi All,
>>> 
>>> I'm doing some work that entails fixing up some digitization based on per-pixel image classification. Sometimes there are polygons with lots of rings contained, so I'm using the Delete  Ring tool, but that requires clicking on every individual ring. Is there a way to delete multiple rings at one time via clicking/dragging with a keyboard key held or anything like that?  
>>> Thanks!
>>> Mike
>>> 
>>> 
>>> 
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