All Questions
24
questions
123
votes
8
answers
354k
views
Calculating polygon areas in shapefile using QGIS
How do I calculate areas of an area shapefile in square meters (m²) or in acres (ha)?
I didn't find that functionality in the Vector Tools.
- 2,321
54
votes
2
answers
91k
views
Understanding difference between Polygon and Multipolygon for shapefiles in QGIS?
Creating Scratch layer gives me a choice between Polygon and Multipolygon, so I started wondering how should I make use of them.
Reading a new book "Mastering QGIS" (through this answer by Joseph to ...
- 31k
17
votes
3
answers
14k
views
Inverting Polygons using QGIS?
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?
...
- 802
6
votes
1
answer
2k
views
Turning vector grid into individual shapefiles using QGIS?
I am using QGIS and I created a vector grid on a crop field in order to cut it into plots. I want to save each grid cell into individual polygon shapefiles automatically.
Here is an example of a ...
- 63
5
votes
2
answers
11k
views
Selecting features of vector layers based on another vector layer using QGIS?
I am using QGIS 2.12.2. I am using three vector layers (point, polyline and polygon shapefiles) of the region of interest. Any advice in making the selections from one dataset based on the other ...
- 1,081
3
votes
4
answers
3k
views
Filtering out labels surrounding active feature in Atlas
Let me put it this way, if I’ve tried data-defined rendering and the common featureid expression and it’s still not working - and I think one or both options should - what basic thing could I be ...
- 31
2
votes
3
answers
4k
views
"Clip" hole into Shapefile
I want to clip a hole into a shapefile.
The underlaying shapefile (greenish) consists of many polygons. The overlaying (red) is only one polygon.
When I use the clip tool I get this
or this ...
- 3,398
12
votes
3
answers
7k
views
Voronoi Diagram on a given polygon using QGIS
I am trying to create a Voronoi Diagram on a specific polygon, but there is some issue when dealing with edges.
Here is how I do it:
Preparing the points for Voronoi and the polygon for the diagram
...
- 365
7
votes
2
answers
2k
views
Calculating shortest distance between points within polygon using QGIS?
I performed a transect in which I sampled several animals. The location of these animals are represented by a point shapefile. I am interested in calculating a pairwise matrix of distance (in meters) ...
- 371
4
votes
3
answers
25k
views
Merging attribute and geometric features in QGIS?
I have polygons shapefile in which some of the polygons have same attributes as seen below:-
In QGIS, how do I merge the polygons having the same attributes into one polygon?
In other words, am ...
- 275
4
votes
2
answers
9k
views
How to edit Shapefile Attributes?
How might I go about exporting a polygon shapefile (e.g. CSV) so that attributes (not geometry) are editable by others, and importing it with the changed attributes (of which there are several columns ...
- 506
3
votes
1
answer
990
views
Closing spaces within polygon in QGIS?
I have a shapefile displaying the borders of several city units. One of its polygons, however, had free space consisting of four vertices in it. I created another polygon inside the free space and ...
- 281
2
votes
3
answers
5k
views
Calculating polygon area within polygons in QGIS
I want to estimate the area of the reef under a polygon grid.
My shapefiles are already in meters, however I am having a hard time calculating the area under the grid layer. Attached are the photos.
I ...
- 21
7
votes
1
answer
10k
views
How to make a multi color map with one shapefile layer in QGIS?
I am working with a shapefile layer of the world. All the countries are in the Attribute table each one in a different row.
I tried to make each polygon in a different color so the countries will be ...
- 2,857
3
votes
2
answers
4k
views
QGIS "Sum Line Lengths" return 'nan.'
I have a polygon shapefile and a (merged) line shapefile (both are zipped). When I use Vector -> Analysis Tools -> Sum Line Lengths on these shapefiles, I get a layer with some of the LENGTHS filled ...
- 31