Questions tagged [area]
Area is a quantity that expresses the extent of a two-dimensional surface or shape, or planar lamina, in the plane.
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Extract a list areas and indices of multi-part polygons (SpatialPolygonsDataframe) R
I'd like to extract a list of polygons from a SpatialPolygonsDataFrame that include more than one area (so a polygon with a hole for example, or just 2 areas in one polygon entry in general). There ...
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1answer
29 views
How to calculate the area of several classes of a raster in a polygon of a vector file with QGIS?
I have some trouble with QGIS
I have two layers of information:
The first one a vector that contains 500 objects, with attributes such as number of population, and...
A raster that has three classes:...
2
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1answer
29 views
Calculate area of ellipsoidal polygon with QGIS
There is online service of GeographicLib, by Karney, where one can calculate the area of ellipsoidal polygon without need of reprojection.
Can one calculate the area of geometry in QGIS so as ...
3
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0answers
17 views
Accurate area calculation for countries worldwide individually [closed]
I have polygons of countries with its administrative divisions, I would calculate the areas of each division in a country accurately.
I got the bounding boxes for each country, then I divided its ...
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1answer
43 views
Over calculation of area- How do I calculate correct acreage when there are stacked parcels?
I am currently interning for a county in the United States. I am working on the data and mapping needed to fulfill the Open Space Activity of CRS. Stacked parcels are causing me a massive headache.
...
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1answer
36 views
What the default unit in QGIS 2.18 $area is calculated and etc?
I'm a beginner in QGIS . We are using 2.18 version.
What are the basic units for area and slope, etc? SI, so means m, m^2, °? Or I can set it by myself? If it's possible to set it, where?
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20 views
Creating catchment area with friction surface using ArcGIS Desktop?
I am using ArcGIS desktop 10.4. I have a shapefile of 494 points. I also have a cost surface/friction surface raster. I want to create a polygon of 13.4 hectares around each point based on the ...
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1answer
30 views
How do I compute the forest area for different regions?
I am currently struggling to compute the forest area of some regions. I am an absolute beginner with Google Earth Engine.
I tried it 2 different ways, mostly by copying and editing code I found.
...
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90 views
QGIS versions yielding different results on $area calculations?
When grading an exam, I discovered that QGIS 3.2 and 3.4 produce different values on computing $area over polygons.
I experimented using $area and area($geometry) to check the differences between ...
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0answers
24 views
How to get the area of the pixels of a raster in Africa Lambert Conformal Conic CRS in R
My question has been previously asked here (R How to multiply the values of the raster pixels with the true surfaces of these pixels?), I have to multiply the precipitation value of each cell by the ...
2
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1answer
69 views
Dissolve using attribute field and area
How can I dissolve a shapefile with polygons and keep the information of the polygons that have the bigger area in QGIS?
example:
two polygons with the same field values but one of them is bigger ...
6
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1answer
123 views
QGIS tool to identify polygons that can fit a certain sized square within the polygon
I am trying to identify parcels with enough space for an additional building, and one of the parameters for this is: there needs to be a space of at least 9' x 10' available to fit the additional ...
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1answer
61 views
Calculating area under each polygon in QGIS [duplicate]
I would like to know how to calculate the area of the vector layer (red in the photo) under each polygon (white square in the photo). The red layer has the area (km2) in its attributes. But what I ...
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2answers
128 views
Calculating polygon area within polygons in QGIS?
I am new to 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. ...
1
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1answer
21 views
Area of classified pixels in an image collection
I am using Monthly History data of the Global Surface Water dataset (Asset id: JRC/GSW1_0/MonthlyHistory).
I have filtered the images using .filterdate and .filterbounds for my region of interest (...
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2answers
71 views
Problem with the ST_Area in PostGIS [duplicate]
I have a question with a query in PostGIS. I try to calculate the area from a polygon. It actually works but the area-result is not correct.
My Query is:
SELECT
name, ST_Area(way)/10000 AS hectares
...
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37 views
Calculating area for polygons in arctic areas
We are evaluating areas of ecological importance in the arctic. The asset areas are of different sizes (up to 10 square kilometres) from latitudes 64 to 80 degrees north. The areas also vary in ...
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1answer
22 views
Measuring areas of polygons in shapefile in the terrain [closed]
How can I measure the actual areas of polygons in a shapefile in the terrain. Some of the polygons in the file is in flat terrain and some in steeper places. Is there an easy way to do this?
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17 views
How to calculate area of 1 x 1 degree cells every one degree?
I've calculated mean data values of each 1 x 1 bin like this:
import numpy as np
from scipy import stats
north=50.5
south=21.5
west=-110.5
east=-76.5
bin_lon = np.arange(west, east, 1)
bin_lat = np....
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1answer
23 views
Raster Symbology Calculate Area Acres
Using ArcMap, I am trying to classify/consolidate the symbology of these agriculture classes into 3 categories: Hay, Pasture/Grass, and Cropland. I also need to find the sum of acres of each of these ...
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1answer
31 views
Calculating area of .shp polygon that intersects with feature of another shapefile
I am using ArcMap 10.6. I created a polygon (red). Some of it overlaps with a feature that delineates a city (green). The brown is where they overlap. In case it makes a difference that the shapefiles ...
4
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1answer
111 views
Selecting an amount of features that together sum up to a certain value?
I am looking for a way in QGIS to randomly select features within my shapefile. The selected features together need to sum up to more or less 2000m2.
So, it is not selecting 10% of the features, but ...
1
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1answer
126 views
Understanding difference in polygon area calculated from ArcGIS Desktop and QGIS?
I'm calculating the area of some polygons and realized that the values are coming out differently when I do the calculations in ArcGIS and QGIS. The data is in Sirgas 2000 and projected for the ...
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1answer
183 views
Calculating Specific Catchment Area in QGIS?
I have tried to calculate the Specific Catchment Area in QGis from Specific Catchment Area and Flow Width Tool available through Saga. However, I got just SCA product with valour 0. I got a reasonable ...
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0answers
27 views
QGIS $area from area calculator wrong [duplicate]
Calculating the $area of a polygon, set to display in hectares.I get this output. Any ideas please
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0answers
25 views
How does one measure the area of a procedurally generated polygon?
Scenario
I have a series of measurements imported as latitude and longitude of a center and a value.
e.g LAT LONG VALUE
Which describes a measured VALUE for an entire spacial area is defined by
...
3
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4answers
114 views
QGIS Geometry $area Field calculator function compared with Cadcorp SIS
I want to know what QGIS uses as a measurement when using the Geometry and $area function. As in is, the area calculated Sq meters?
I am getting two different answers when using Cadcorp SIS and QGIS:
...
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1answer
30 views
Calculating area of raster for value range using ArcGIS Desktop?
I need to know the area occupied by values between 0.2 and 0.8 for my raster
class : RasterLayer
dimensions : 1813, 1883, 3413879 (nrow, ncol, ncell)
resolution : 0.0002704818, 0.0002704818 ...
1
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1answer
68 views
Area difference between polygon layers
I would like to calculate the difference of area between two polygons. I tried using the Difference tool, but all it does is create lines that are different between my two polygons. I also tried the ...
1
vote
1answer
368 views
How to calculate the polygon area and create a column of results in R
I'm working with shapefile in R and I need to calculate the polygons' area that I created by Gdiference function, So ,now I need to create a column with the size of freshly polygons created, because ...
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0answers
14 views
vector from raster, with the information of the raster, for area estimation
As you will probably understand, i am new to using GIS applications and software. So far, i tried SNAP and now i am trying to learn just a few modules for certain research applications, in QGIS. I ...
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0answers
96 views
Difference in area calculation between QGIS and R
I used R to calculate the area of every land polygon of the world (Projection of the source shapefile: WGS84; CRS: EPGS: 4326).
To do that, I loaded the required packages ("sp" and "raster") and I ...
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1answer
363 views
Calculate area with OpenLayers4 and Turf.js
I've been working with OL4 for a few months now but this is the first time I try to calculate an area and after some research looks like Turf.js seems like the way to go.
First, allow me to add all ...
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1answer
57 views
Filtering out clusters of features based on collective area threshold using QGIS/python?
I have a map I generated that roughly estimates timber industry land ownership (designated by the green on the map) in the counties surrounding the Salish Sea in the US state of Washington:
I want to ...
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1answer
47 views
Selecting a subset of a raster, based on aspect and slope, as input to calculate area
Background
I created some digital elevation models and subsequently made a 2 layer raster for each containing the calculated aspect and slope using raster::terrain. Now I want to calculate the area of ...
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0answers
26 views
Calculate Feature Area in Shapefile, which crs to use?
For a global shapefile I would like to calculate the area per feature. If I understand correctly it is best practice to reproject your shapefile to a projected coordinate system. In the past I've used ...
2
votes
1answer
106 views
Postgresql - problem updating row with complex calculation
A calculation for the replacement value of a tree exists:
Variables:
index_price for species;
circumference of tree;
condition measures: vitality, root_injuries, stem_injuries,
crown_injuries
(A ...
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0answers
51 views
How exact is $area?
Background: I am doing some area statistics (how much of different properties is used for a specific type of use) based on ACAD-constructions. Both the from dxf converted shapes and the baselayer with ...
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2answers
68 views
How to check whether a feature has been split in GeoTools?
In my program I am looking for a best place for a golf course. Three of the conditions are:
The course must be on a hill,
it must be at least 100 meters away from roads and
must not be larger than ...
0
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1answer
41 views
Splitting One Polygon By Boundary of Another using QGIS?
I'm using QGIS 3.0 and attempting to calculate the number of people that fall within a buffer. The population count is a field within my block group polygon layer. I've attached a screenshot, the ...
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0answers
58 views
Geometry column-saved derived area data not the same as “identify features” area [duplicate]
I've been through a lot of the already posted answers and can't seem to get this to work. I'm using the old Pisa 2.10.1 (slow internet means no updates). I'm trying to calculate the proportion of ...
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0answers
95 views
Area calculation in turf.js in a projection other than WGS 84/World Mercator?
Is it possible to calculate the area in turf.js in projection other than WGS 84/World Mercator (assuming the original data has a different projection)? My understanding is that turf.js only supports ...
5
votes
2answers
160 views
Creating a raster of percent of pixel occupied from shapefile [closed]
Starting from a polygon shapefile, How can I produce a 1km raster, where the cell values are the percentage of the pixel occupied by the shapefile. For example the values would range from 0 to 100%. I ...
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0answers
41 views
Area calc gives odd answers [duplicate]
I made a shapefile from a DEM raster of Ethiopia, and I want to find the total area of the shapefile. I have changed the CRS of all files to Africa_Albers_Equal_Area_Conic (ESPG: 102022), and the ...
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0answers
149 views
Differences in Area calculation methods Google Earth Engine?
I calculated the area of my river basin twice and got different results and do not know why/what exactly happens.
At first, I just wanted to have the whole area of my river basin, which I did by:
//...
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2answers
299 views
How to get MultiPolygon from MultiPoint for area calculation in Postgis?
I have PostGIS database table with geometry records containing MultiPoint. When I try st_area(geometry), I get 0. How to convert it to MultiPolygon to calculate covered area if we assume that a point ...
3
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0answers
51 views
Find the intersecting area of more than 2 polygons in QGIS
I have a map of 7 species distributions. I want to create polygons of the area where all 7 overlap, 6 overlap, 5 overlap etc. I created a polygon of where any 2 species overlap using the intersect ...
2
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1answer
49 views
Adding up polygon areas involved in a single area in QGIS
I have a polygon shapefile comprised of 4 polygons representing landslides (see image). None of them are overlapped.
Number 1 comprises everyone (2, 3 and 4). Number 4 comprises number 3. Finally ...
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0answers
27 views
Export / Import training areas
I am using GRASS GIS 7.4.0 to classify the raster. First I defined the area using Vector digitization option in "GRASS GIS Supervised classification tool". I exported the same and closed the window , ...
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0answers
46 views
Creating a polygon that shows the specific elevation above a river using a DEM
My goal is to determine the possible area covered by interpreted Tertiary drainages. To keep my example simple, I have a DEM and a River polyline. I would like to see the area a polygon (or raster) ...
