I have a point layer for the cold air flow in specific region. I would like to simplify all the single points to a polygon shape as to be able to join the data with other spatial data. My way is pretty complicated (buffer the points e.g.400m, dissolve, simplify) because I have to extract the single values (orange, blue, light blue) and then do it with all these single values separately. Afterwards there is the need to create differences in order to avoid doubles. I wonder if somebody knows a more convenient way.
120837
I want to know if there is a plugin in QGIS, which will allow me to draw the outline a point cloud. I know there Points2One the plugin, but it makes an outline with all points, even with the data found in the middle of the point cloud.  I give you an example ;  x       y       ID      order 3.3     43.2625 353293  1 3.13334 43.3458 353293  2 3.21667 43.3458 353293  3 2.88334 43.4292 353293  4 2.96667 43.4292 353293  5 3.05    43.4292 353293  6 3.13334 43.4292 353293  7 2.71667 43.5125 353293  8 2.8     43.5125 353293  9 2.88334 43.5125 353293  10 2.96667 43.5125 353293  11 3.05    43.5125 353293  12 3.13334 43.5125 353293  13 2.88334 43.5958 353293  14 2.96667 43.5958 353293  15 3.05    43.5958 353293  16 3.13334 43.5958 353293  17 2.96667 43.6792 353293  18 3.05    43.6792 353293  19 3.13334 43.6792 353293  20 3.21667 43.6792 353293  21 3.05    43.7625 353293  22 3.13334 43.7625 353293  23 3.21667 43.7625 353293  24 3.13334 43.8458 353293  25 3.21667 43.8458 353293  26   With the tool suggested by @ArMoraer I can only draw a polygon with the outer points that are more extreme. The polygon has touched just 5 points (see map of Convex hull below) but normally it should pass on 20 points (all points of the contour).     Each point has a pixel, actually the outline should not touch the points but it must pass through the outer limit of these pixels. In the end I want to have an outline like this map (see map below : desired contour)
111414
Using QGIS v2.6.0-Brighton.  This question is not about editing layers geographically in anyway. It is merely trying to find data from two layers as you would in an SQL Query and append an extra ID to the second layer.  I have one polyline layer each identified with two different IDs. There is a point layer also with one of these IDs, I wish to find this corresponding ID and append them as a column to the point layer.  How do I do this without finding each row individually and typing it in manually (i.e. larger scale)? I would prefer to use SQL like syntax but if there is a GUI as well that would be ideal. Happy to install official plugins.
60314
I have a polygon layer without data, and a point layer with attributes.  Each point is contained in one polygon, and I would like to have the data from the point layer joint in the polygon layer, so every polygon has the data from the point contained in it.  Is this possible with QGIS?
51492
Assuming a series of points in 2d space that do not self-intersect, what is an efficient method of determining the area of the resulting polygon?  As a side note, this is not homework and I am not looking for code.  I am looking for a description I can use to implement my own method.  I have my ideas about pulling a sequence of triangles from the list of points, but I know there are a bunch of edge cases regarding convex and concave polygons that I probably won't catch.
78049
I found  in the old ESRI forums with the same type of problem I am facing today. The solution to the problem is explained in little detail and since I am not an expert, I was wondering if somebody could describe it to me in little more detail.  We are doing a mental map analysis. We have let's say 50 polygons of a certain city square which are all different in shape, size and location. Our goal is to create a single polygon which would represent the answers from our whole input data. So basically, we need a method for generating a single polygon out of these 50 which would be an "average" polygon in size, shape and location.  Can somebody explain the process?
113953
I have a road network as line layer and a land cover as polygon layer, I want to find number of subpolygon for each polygon that divided by line layer in QGIS?  I used union function in Geoprocessing Tools in Vector menu of QGIS and then polygonize function to convert union result to polygon but in table of new polygon there is NULL data.
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.
52459
I've a Google map with bunch of polygons on it.  Here is a problem I'm interested in: Given a lat,lng point, what's the best way to determine all the polygons that this point lies in?  The obvious way is to run a "point in polygon" algorithm iteratively for each polygon, but I was wondering if there an efficient algorithm to answer such queries especially if you have thousands of polygons.
32064
I have been trying to create a function that does basically the same thing that the QGIS "dissolve" function. I thought it would be super easy but well apparently not. So from what I have gathered around, the use of fiona with shapely should be the best option here. I just began to mess around with vector files so this world is pretty new to me and python as well.  For these example, I am working with a county shapefile founded here  So here are some piece of code I gathered but can't find a way to make them work together  For now my best method is the following based on : . It works fine and I get a list of the 52 states as Shapely geometry. Please feel free to comment if there is a more straight forward way to do this part.  from osgeo import ogr from shapely.wkb import loads from numpy import asarray from shapely.ops import cascaded_union  ds = ogr.Open('counties.shp') layer = ds.GetLayer(0)  #create a list of unique states identifier to be able #to loop through them later STATEFP_list = [] for i in range(0 , layer.GetFeatureCount()) :     feature = layer.GetFeature(i)     statefp = feature.GetField('STATEFP')     STATEFP_list.append(statefp)  STATEFP_list = set(STATEFP_list)  #Create a list of merged polygons = states  #to be written to file polygons = []  #do the actual dissolving based on STATEFP #and append polygons for i in STATEFP_list :      county_to_merge = []     layer.SetAttributeFilter("STATEFP = '%s'" %i )      #I am not too sure why "while 1" but it works      while 1:         f = layer.GetNextFeature()         if f is None: break         g = f.geometry()         county_to_merge.append(loads(g.ExportToWkb()))      u = cascaded_union(county_to_merge)     polygons.append(u)  #And now I am totally stuck, I have no idea how to write  #this list of shapely geometry into a shapefile using the #same properties that my source.   So the writing is really not straight forward from what I have seen, I really just want the same shapefile only with the country dissolve into states, I don't even need much of the attribute table but I am curious to see how you can pass it on from the source to the new created shapefile.  I found many pieces of code for writing with fiona but I am never able to make it work with my data. Example from  :  from shapely.geometry import mapping, Polygon import fiona  # Here's an example Shapely geometry poly = Polygon([(0, 0), (0, 1), (1, 1), (0, 0)])  # Define a polygon feature geometry with one attribute schema = {     'geometry': 'Polygon',     'properties': {'id': 'int'}, }  # Write a new Shapefile with fiona.open('my_shp2.shp', 'w', 'ESRI Shapefile', schema) as c:     ## If there are multiple geometries, put the "for" loop here     c.write({         'geometry': mapping(poly),         'properties': {'id': 123},     })   The problem here is how to do the same with a list of geometry and how to recreate the same properties than the source.
60531
Lots of questions about turning metes and bounds into a polygon, but how about going in reverse? Are there any existing tools or do I need to look at building a script myself?  Ultimately I'd like to generate points with x/y and at all the vertices and line segments with distance and direction as attributes (so I can label them).   This for submission to our local government as part of their legal requirements.
1829
I am new at using QGIS. How can I simply split features in QGIS? The manual tells to simply draw a line through the polygon you want to split. But it doesn't work. The line disappears when finishing it. When I select the polygon and then split it, it sometimes works and sometimes doesn't (an info appears after which it does not split the feature). Does anybody have an idea why the tool does not work properly?
109560
I am using ArcMap 10.0. I am trying to edit (and add) vertices in a polygon.   I start editing, (using "Edit Vertices" tool), and add many vertices in the polygon.   Then when I am done, I save the changes. But, the image gets simplified and I lose many of the additions!  Why is the editor deleting some vertices and simplifying the polygon?
6907
I want to convert polygons into points using QGIS.   I know how it's done in ArcGIS Desktop.
28459
I have a line layer and a polygon layer. Both files have the same SRS. I want in a new shape file only the lines covered by the polygons.   I tried in QGIS the Vector -&gt; Geoprocessing -&gt; Clip tool but I only get an empty shapefile.  How do I do this with QGIS?
113395
I have a set of points, which are spread over a wide geographical area.  I need to be able to create a set of polygons which best represent the clustered points.  In parts, some points may simply lie on their own, but in the main they are grouped, but not linked.  I have effectively created a grid of, lets say, the north western hemisphere and in each grid, have created a point with an arbitrary value.  For all values of zero, I have deleted the points, leaving the points with non zero values in them.  I now need to turn these points into polygons and am struggling a little...  Using ArcGIS and python, I thought about clustering the points, then 'convex hulling' them, but am struggling through not really knowing ArcGIS that well; how do I cluster?  thanks in advance for any help.
80652
Is there a way to make some "2D solidify" from edges to faces. (It's about creating roads from GIS data). I've tried Skin modifier, converting to curves with depth and back to mesh, but all the methods resulted in a dirty mesh with lots of intersections and bad geometry. The problem seems to be that simple and straightforward that it simply must have a simple way to solve. But I don't see it. Please, point it out.
43989
In the Upslope Area tool from SAGA it used to be possible to import the point file with multiple points and it would create several catchment/basins areas for those points. Now, it is only possible to MANUALLY enter coordinates for only 1 point. However, for a model we're building, we need to perform this analysis 24 times (as we have 24 different points) so we need to automate this process. I tried to use Run as Batch process + calculate by expression and get the XY coordinates from another layer, however, I run into the problem that I need to reference the XY coordinates that are stored in the other layer and looks like there isn't an easy way of doing so. Any suggestions on how to do that? Tried the geomwithin(targetLayer,targetField) from RefFunctions plugin but that produces empty result  so to resume, I have two questions:   How to calculate upslope areas for multiple points? Is there a way to automatize it in the graphical modeler?