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I'm working with Quantum GIS at this moment. And as the title says, when I finish drawing a polygon, it disappears again. The new object does appear in my attribute table and in the legend/'filling of the polygon' should not be the problem. Before this never happend, so I supposed it was some change I made in the options. But even after reinstalling the program the problem stays. After searching for a while I discovered that on a new project it works correctly till the moment I import a vector-file I made before with line objects. How can importing a file have such an influence?

Thanks in advance!

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Settings -> Options -> Digitizing -> On 'Suppress attributes pop-up windows after each created feature' - in this issue? –  HasT Oct 11 '12 at 11:27
    
Hi, thanks for your reply. I think that is not the problem. I can add atributes to the created polygon, it is visible in my attribute list, but the polygon is not visible. The other polygons of the same layer are. –  Silke Oct 11 '12 at 11:39
    
Is your Layer using categorized style or rule-based symbols? If it is, and you are not giving one of the classified Values to your polygon, it won't be visible in the map as it has no symbol to draw. If that is the case, just reclassify the style, or add the new Value. –  Alexandre Neto Oct 11 '12 at 12:03
    
I tried categorized style by adding categories, using existing categories and also using the only-symbol function. It seems something else is going on, because I can make polygons, till the moment I add an existing vectorfile (consisting of lines in this case). –  Silke Oct 11 '12 at 12:50
    
Sorry to ask obvious questions, but, did you try to open the shapefile in another other project? Does the Layer have any query? Can you send the file so we can check it? BTW what Qgis version are you using? –  Alexandre Neto Oct 11 '12 at 13:15
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1 Answer 1

I have figured this out. My project included tracing multiple river islands and sandbars, and 9/10 times my painstaking sketches disappeared using the auto-complete freehand or polygon tools. I noticed that the 1 polygon out of 10 that was created was a bit messy, i.e. the last line or point crossed the initial line or point where I started the shape. It seems in order to complete a polygon using these toos, your finishing line has to cross over a portion of where you started. Then hit F2 or right click and click "Finish Sketch." Works fine now. Good luck!

(see image below)

enter image description here

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