How can I split the green area as a separate polygon fro the grey one in QGIS?
120785
Is there a QGIS equivalent of the  tool in ArcGIS Desktop?  The Erase tool:     Creates a feature class by overlaying the Input Features with the   polygons of the Erase Features. Only those portions of the input   features falling outside the erase features outside boundaries are   copied to the output feature class.
35644
I have a set of data as polygons, each with a Number field with value X. Is there then a way to copy this into X number of polys at the same location? (ideally points distributed across the poly but that's a bonus).  In QGIS I have tried Random Points, but this doesn't inherit attributes, and Join Attributes by Location is useless if the parent polys overlap.  The reason behind this is for collating data easily with the GroupStats plugin.
240
I have a point shapefile of villages where data was collected in Northern Kenya. I created a buffer around those villages.   The second vector layer contains polygons defining areas according to vegetation type. So for example, a forest might be surrounded by a narrow ring of woodland in an area which is mainly grassland. I'm trying to obtain a percentage of each vegetation type within the buffer per village.   I'm using QGIS 1.7
85482
Given polygons - like landcover in OpenStreetMap or street areas in cadastre - how can one suppress those polygon boundaries which are shared by objects (features) of same type in QGIS (see figure below)? AFAIK there exists no such symbolization rules in QGIS 2.6 (yet). It doesn't seem useful to aggregate (union) the geometries. But preprocessing could still be an approach, like splitting the common boundaries first, then &quot;suppressing&quot; these when rendering. Any ideas?
21319
I am a relative beginner to using GIS, and am running QGIS 2.0.1 in Linux. I have two historical maps which I want to analyze, that show land use patterns in the same area at two different moments in time. I have them scanned and geo-referenced as layers in one file. Side by side, they look like this:     The main thing I am interested in is to compare the extent of the light and dark green areas between the two maps. Is this possible, and if so, what is the simplest approach? Is there a way to do this based on raster analysis? And if I have to make a shapefile, what is the best way to do that?  What I have already considered:   Drawing shapefiles as polygons by hand, as described in . That would be VERY tedious. Creating simplified, high contrast raster images by using color selection, filters etc. by trial and error in the Gimp and converting that to a shapefile. The results were very sloppy.
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.
80173
I have a woodland scheme advice layer that has a polygon for each area of advice (brown layer in the picture). I also have a polygon layer of UK local authorities (red boundary layer in the picture). I would like to perform a spatial query which returns the local authority name for each woodland advice scheme. This would work fine if each woodland advice scheme was found in just one local authority boundary. However many are found across a boundary of two different authorities. For instance, one scheme sits across the boundaries of the authorities of Fife and Angus. The scheme is the yellow selected polygon in the picture and the red line is the authority boundary. How do I get the spatial join to return a value of Fife; Angus (or something similar to identify two values) instead of just Fife or Angus.
16607
I work with this polygon and try to find a way to create a new polygon from the empty gap (not distinguish it) in the middle of the polygon.  I succeed to do it with a "Difference" tool but used with another layer on the polygon and then using the difference tool.  I can also digitize the shape of the hole and create a new layer I seeking an automated way to do it and not doing in manually.   I read:        Is it possible to do it with a direct tool in QGIS 2.18.1, without the aid of another layer?
20212
In this project, I have three polygons, see the image below  'Polygons_From', includes input attributes, i.g. &quot;Value_1&quot;, &quot;Value_2&quot;, &quot;Value_3&quot;, and $area for each quadrate (on the image there are two types of them). 'Polygons_To' polygons for which new values &quot;Value_1_new&quot;, &quot;Value_2_new&quot;, &quot;Value_3_new&quot; need to be defined 'Border' defines an area where the calculation should be done.   My task is to transfer values from 'Polygons_From' into 'Polygons_To' based on a certain aspect/ratio. Of course, I can simply achieve it with the 'Union' function as was suggested in . It uses $area-factor, but perhaps there are better approaches that will lead me to a much more efficient output? So, I am asking for a recommendation regarding the technique/workflow that can be applied in QGIS 2.18. Shall I consider only $area or there are some other criteria? Moreover, I looking forward to finding some papers that may improve my general understanding of the methodology.  References:
115697
I have a polygon layer in QGIS, and would like to represent the polygons like in the below image:    I have tried two different approaches, none of which are satisfactory.    Using a line pattern fill, the entire polygon is filled with the line pattern. I need a blank area in the middle which is not filled in.    Using a marker line fill, I am able to keep a blank area in the middle, but the markers are rotated to align with the edges of the polygon. I need the markers to preserve the same rotation along all edges, like in the example above.  Any ideas?
116844
I have a polygon shapefile storing hexadecimal color codes in a specific attribute.    gid    |   label   |   color ---------+-----------+------------ 1        | Crops     | #FF5F2C 2        | Forest    | #00FF00 3        | Pond      | #0000FF 4        | Forest    | #00FF00   I was looking for a way to say QGIS to read these values in order to style the polygons with them. I can't find anything about this.   I hoped it would be possible without deeping into the Python Console (which still frightens me...).
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.
89861
I have a pdf with the area of a county that I want to separate into multiple shapefiles (polygons) based on color.   As shown in the first picture there are 4 colors so I would need to separate based on color between those four. But first, I need to convert it into a vector (unless there is an easier way).   Doing so, I get the second image as an output by using the polygonize tool which when zoomed in very close, has a lot of tiny squares where color should be different. I was wondering if there is a way to break a raster up by color even though the image isn't smart.
79890
I'm new to desktop GIS, and will try to ask while lacking the proper terms from the GIS lingo:  If QGIS was like Photoshop I would like to make a selection from one layer, and then match that selection to another layer to get the overlap between the two and create a new layer from this overlap.  Formulated in another way:  I want to select all land from each of the Norwegian municipalities. In the shapefile I have (you can download it here: ) municipality borders are found as "N5000_AdministrativGrense" (just the borders) and "N5000_AdministrativFlate" (borders and the land within each municipality). This data (borders and land per municipality) is too administrative - it includes ocean and we have a lot of fjords in Norway. I need the landmass minus ocean.  The landmass is found in the layer "N5000_ArealdekkeFlate" - or so it looks to a novice at least.   So - I want to find the intersection between the landmass (only land, no ocean) and municipality borders and make a new layer that is all municipalities without ocean.  I'm on a mac with QGIS as my installed tool. All tips, pointers and help is much appreciated.
91538
I have a Shapefile with Polygon features  representing the world's land areas (continents, islands).   Is it possible to invert these, and get a geometry that represents the world's oceans and seas?   So the original land Polygons need to become rings in a single global Polygon that covers the planet.  Basically, I'm looking for something like Select > Inverse in Photoshop.   I am using QGIS.
114021
I have two feature Datasets. Both are Polygons. Dataset A has very big Areas and Dataset B just small ones. Now, B still overlaps in 2 or 3 Zones from Dataset A.   I want to perform a spatial join and put the result comma seperated in just one row like this:  Zone_ID_A  |  Zone_ID_B     1       |   2,3    2       |   2,4    3       |   5    4       |   1,6   I know this is possible with ArcMap but i could not figure out a way to do this in QGIS, any ideas?
44057
Here is what I'd like to achieve in QGIS.   Is there a processing tool to remove the overlapping part of polygons?    It is also very important that they do not get merged during the process and that they keep their original attributes since I need to work with them afterwards.