All Questions
65
questions
1
vote
1
answer
48
views
Calculate ratio of 2 polygons using QGIS modeler
Working with QGIS modeler, I need to do some arithmetic operations with some polygon areas.
Let's say there are 2 polygons in layer A and layer B. And I'm inputting them into the model using Vector ...
- 74.8k
1
vote
1
answer
1k
views
Processing area and calculating volume of polygon with know elevation from DEM in QGIS
I got a DEM of a watershed and I need to create a dam at a fixed elevation (with a rectangular polygon corresponding at the top of the dam) and calculate it's area (including the slope (fixed value) ...
CommunityBot
- 1
1
vote
0
answers
83
views
QGIS ellipsoidal area values changing very slightly between calculations while planimetric values stay the same
I have a number of vector shapefiles that I need to calculate the geodesic/ellipsoidal area for. These shapefiles are accessed and updated regularly, with the area recalculated each time they are ...
- 57
1
vote
2
answers
67
views
QGIS Count values between two numbers inside a polygon in another layer
I have 2 layers.
LayerA are multiple polygons of the area that i'm evaluating (Red boundarys).
LayerB is a MSAVI raster to vector with the data (multicolor greens - blues).
I want to calculate the ...
- 73.1k
0
votes
1
answer
709
views
QGIS calculate area automatically
Is there a way to calculate area automatically when I edit a polygon? I mean, is there any function there I can use on area field and update itself when I finish editing?
CommunityBot
- 1
3
votes
1
answer
1k
views
Calculated area is too large using Field Calculator in QGIS
When I run the Field Calculator to update area, the resulting areas are too large. This happens whether I use QGIS 2.18 or QGIS 3.4.
The default CRS is set to: ESPG:27700, OSGB 1936 / British National ...
- 33.3k
14
votes
2
answers
57k
views
Calculating polygon areas and perimeters using QGIS
Using QGIS, if I load a polygon layer and make a new column, how do I fill that column with the area of each polygon and another column with the length of the perimeter of each polygon?
- 33.3k
0
votes
1
answer
74
views
Adaptive polygon division in QGIS
Let say I have an irregular polygon layer that I want to divide into squares of fixed size (i.e. 50 x 50m). The simplest solution is to create a grid based on the polygon extension and then use the ...
- 86
4
votes
1
answer
99
views
Add polygon areas by roof orientation condition
I have a shapefile with building poligons and a raster file with the roof orientation (0-360º). I would like to assign the orientation to the building shapefile using QGIS. I converted the raster file ...
- 34.9k
4
votes
1
answer
169
views
Why area of intersection differs from total area of polygon?
I calculated intersection between Layer 1 and Layer 2 using expression below:
area(
intersection (
$geometry,
collect_geometries(
overlay_intersects ('layer1',$...
- 41.1k
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.
- 33.3k
3
votes
1
answer
142
views
Create competing polygons from points and bearings (azimuth)
I have a set of points on a city, representing CELL TOWER locations. Each CELL TOWER has 3 or 4 different CELL RADIOS pointing to diferent directions (Azimuth). What I need is an algorithm to take ...
- 73.1k
2
votes
1
answer
75
views
Merging all polygons (and their respective attributes) into similar areas in QGIS
As you can see in the image, I'm trying to merge selected polygons and their respective attributes. I have thousands of these polygons (some very small, others very large). I have to create areas of ...
- 76
3
votes
2
answers
268
views
Calculate the percentage of a polygon either side of a line
I have a series of polygons outlining distributions of various fish species around Australia. I am relatively new to GIS.
I am trying to class each species as either tropical or temperate based on the ...
- 73.1k
1
vote
1
answer
103
views
Calculating area's region in DEM
I have a DEM map in my project Tsunami Assesment project.The white area below the mentioned map is sea and we know that possible tsunami height is 14 meters(please neglect the line, there is an error ...
- 73.1k