I have a multipolygon layer. Some of the polygons within the layer overlap. I would like to dissolve only the polygons which overlap and not any discrete polygons. Is this possible? I am currently using QGIS.
121846
I am a fairly new user of QGIS having a question regarding dissolve functionality.   I am working with the  provided by EU, which I have imported in QGIS. I have created a new layer with only Denmark and Netherlands as you can see in the picture below.     The corresponding attribute table is the following.    The fields describe the ID and name for each NUTS node, as well as the country code. I have introduced a new attribute field, called Merge_attr.  I have managed to dissolve the polygons with the same attribute value of Merge_attr. However, I would like to dissolve polygons based on the Merge_attr value only when they belong to the same country and potentially only when they are adjacent.  Can we constrain dissolve functionality to only polygons that are adjacent?  This means that the following should not take place (yellow polygons got merged even though not adjacent):
56062
Is it possible to smooth or generalize a polygon in QGIS, perhaps by using a plugin like the generalizer-plugin for lines?  I could convert my polygons to lines, smooth them and convert them back to polygons but this is not working for my polygons because of several reasons.
65803
I do a lot of editing, in this case areas. Sometimes I add an area to one shapefile, only to realise a bit later that it should have been in another.   Is there an easy way of copying only that polygon into the proper shapefile? Something along the lines of rightclick the row in attribute table, copy and then paste in the next attribute table.   I do know that I can select the polygon and use , but this seem unnecessary complicated?
112738
I have 100 polygons in a GeoJSON file that partially overlap each other. I would like to produce 100 new polygons as follows:   The area covered by any of the original 100. This is their union. The area covered by at least two of the original 100. ... The area covered by all but one of the original 100. The area covered by all of the original 100. This is their intersection.   (I'm actually going to only keep 5-10 of these 100 results, but I expect the process for generating all 100 of them is the same as generating a subset of them)  What software / functions can I use to do this?    One approach I've already encountered in another similar project involves rasterizing all of the original polygons, then counting the overlapping pixels and producing new polygons from that data. This approach loses precision earlier than I would like to (I want to maintain near perfect precision up until the end of the process, THEN simplify things for display).    I could do this semi-manually with hundreds of union and intersection operations. This approach is not ideal because I want to re-run this process at intervals in the future as the dataset grows.
50920
I want to merge two shape files in which one is of point geometry type and other is polygon type in order to get a single layer containing both points and polygon in a single map.
105745
I have a polygon layer on top of a DEM.  Is there a way to clip the polygon layer according to elevation, ie the clipped result being only those areas of the polygon layer between x and y altitude?  The result needs to be a vector layer.
32012
I have several polygon objects and I need to "merge (or combine or dissolve)" them toghether into one polygon object. With a GIS tool like QGIS, I do this with processing option "Combine selected spatial objects" and the result is what I expect but doing programmatically with Java and GeoTools library, I'm not able to get this behaviour.   To give you an idea, I have two polygons in one layer like this:    Each square is an independent polygon in my shapefile (an independent object with its attributes).  Now I want to transform them into one object. I tried with "union" method of Geometry class in this way:      //polygon1 and polygon2 are Polygon objects (the squares in the above image)     Geometry combine = polygon1.union(polygon2);   And this is the result when I visualize the union in the GIS:    As you can see, a line is added between the two figures (although the union is made succesfully and I have only one entity as I wish) but I want this without the line connecting them.  The polygons are well formed because by doing with QGIS the operation is made right.   Anyone know if is it possible?   I'm looking for some time and I'm concluding that maybe my approach to achieve this is bad.
99536
I have a map made up of multiple polygons, with a few hundred thousand points very small polygons on within it.  I need the larger polygons, but not the points small polygons.  How do I select and remove all the points small polygons, while preserving the larger polygons?  (I obviously do not want to do this manually - there are a few too many points for that!)  I'm totally new to QGIS, and I've Googled extensivey with no luck.  Probably because I'm unsure what the correct terminology to use in a Google search is!  The files I am using are a .dbf, .prj, .qpj, .shp and .shx.  I'm simply dragging the .shp file on to QGIS, and the map appears as one layer.  Basically a map of the UK divided into regions (which I want) and covered in points (which do not want).     This is what it looks like up close.  I did a dissolve to see if they'd go in to the surrounding layer, with no luck:
62326
I have a PostGIS table of polygons where some intersect with one another.  This is what I'm trying to do:   For a given polygon selected by id, give me all of the polygons that intersect.  Basically, select the_geom from the_table where ST_Intersects(the_geom, (select the_geom from the_table where source_id = '123')) From these polygons, I need to create a new polygons such that intersection becomes a new polygon.  So if polygon A intersects with polygon B, I will get 3 new polygons: A minus AB, AB, and B minus AB.   Any ideas?
52790
I have two layers. Layer 1 contains points (x,y) and layer 2 contains one polygon. All points in layer 1 are positioned within the polygon of layer 2. The points in layer 1 contain an attribute with information on the topography/elevation at the specific point. Can I color the polygon in layer 2 based on attributes from the points in layer 1 in order to create an elevation map?
49373
I have a polygon layer (where each feature has a class attribute), and a point layer, and there are at least 10 points within each feature of the polygon. Is there a way to randomly select only &quot;k&quot; points of these 10 points for each feature (class) in QGIS?  Thanks!
93142
I have a shapefile with 16,400 polygons. Each polygon shows the expansion of a bird species for the whole world.    Now I have to count the overlapping polygons. I tried it with union and dissolve (count the union), but the union is not working for so many polygons.   Then I tried to clip continents, but this is also not working because of the huge number of polygons. Moreover I tried this  , also without success.   Therefore I'm asking you I there is a way to count overlapping polygons if 16400 polygons are in one shapefile?   I'm working with 10.0 and can work with 10.2. An ArcPy solution is also wonderful.   At the moment I am thinking about creating a fishnet and iterate over the rows of the shp with the 16400 polygons and write 1 to a value field of a fishnet cell if the polygon is in this cell and than take the next row (polygon) and if this is also in the fishnet cell count +1.   But I don't know if this is a good solution and how to realize it. Or I have to learn R to use this   The result: It should be a shape where you have new polygons out of the overlapping ones and a field where the overlaps are counted.    So in the end there should be a shapefile where you can see how many bird species are found at the same place.
35400
I have several shp files which are the components (or tiles) of a map, I have joint all these tiles together to have a large shp file. Then I realized some of the polygon is now split into 2 halves, as the upper part belongs to a tile, while the lower part belongs to another tile.  This output disturbs me a lot as I need to fill some polygon, but not part of the "split polygon", so I need to find a way to merge these split polygon back to one (preferably mechanical way, as I have 10000+ polygons, not knowing which are split, which are not).  I need to know if the two or more polygons originate from the larger polygon. And I think I can somehow use union and spRbind to create an algorithm for this task. But I doubt if I am really the first one who encounters this problem, so I wonder if there is any existing tool in R that can solve this.  Thanks.
47596
I have been given a shapefile from a client that features pivots, yet they were recorded as 10 circles overlapping. The software my company uses requires that these polygons be rings that don't overlap. I have read about the clip and difference tools, but I think I'm going about it the wrong way.   Can anyone help me clip these polygons so they are rings and not overlapping circles?   I have attached a screenshot of what I mean.
44793
I need to create test file for my program. But it only accepts polygons with 3 vertices - triangles as input. How can I convert all polygons of some object into triangles?  I know how to select all faces, but how to split them into triangles.
71694
I have a set of points (meteorological stations) with 5km buffers around them. Additionally, I have a set of polygons (municipalities) in which those stations are located.  I would like to have data on how much of the buffer is filled by each polygon but I was not able to find a function or a way to do it. So for example for point A I would have that in the buffer of 5km there is 80% of polygon B and 20% of polygon C as the output.  Edit:  The anwsers provided do anwser this question in a setting in which I know what polygons and buffers I need to have in the code or when I can do it manualy. Problem is that in my setting with 1 shapefile having 500 polygons and one vector layer having 13000 buffers I am unable to do this manually and I am asking if there is an easier way to do it. I tried implementing the approaches in the questions but I was unable to use them on my example in big scale. Moreover I had problems with coding that I also noted in comments down below.   Main difference to the other similar question provided is that I have 2 vector layers (Buffer with 500 buffers and Municipalities a shape file with 500 different polygons). Previous questions were analyzing this question in situations in which I know precisely the polygons and buffers analyzed, at least that is how I understood them, so after trying to use those approaches on my datasets I was not able to replicate them.  Another way of approaching this problem for me is to use join attributes by location -one-to-many and then getting averages of the duplicate results, only problem is that then I take average of polygons instead of their weights corresponding to % of intersection with the buffer. In my case I do not know what polygons of the shapefile are going to intersect what buffers, or even if the buffer is going to be intersected by 1,2 or more polygons
24602
I have a polygon which is actually composed of many polygons but it results as unique geometry in the shapefile. It's easier to explain with a picture. The yellow parts are in my shapefile a single polygon. I want to make each part be a different polygon with different attributes.    I tried with "Multiparts to single part" but the result is another layer with only those polygons. I need instead a unique layer.