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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17 views

Converting a classification raster to a polygon, in order to calculate the area of each land use

I have 6 land use categories. ultimately I would like to calculate the area of all of the classification categories in my layer e.g. the area of the deforestation, or the area of primary forest. I am ...
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2answers
70 views

Forest change tutorial results don't make sense compared to area of the country

I've been following this Earth Engine tutorial on calculating forest loss by country, and running that same code for multiple other countries. What I had matched the expected output that the tutorial ...
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How to performing selection by expression using QGIS

I am using QGIS 3.8. I have a grid (hexagon) and a set of points. I am trying to select the hexagons containing at least 1 point. So far nothing complicated. Except that sometimes my points overlap 2 ...
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Finding areas for each polygon in multipolygon layer - CRS issues - QGIS [duplicate]

I have a layer of townlands - this is Ireland - so within that polygon layer are the various smaller townland polygons. I wished to calculate the area of each townland into an attribute I had created, ...
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2answers
3k views

Calculating area of polygon in WGS84 Shapefile using QGIS

I am using QGIS 2.12.3 Lyon and I want to calculate the area of my polygon in m2. For that I used the tool provided by QGIS, but the result is not as it should be. I got from QGIS 50 ha, while I got ...
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1answer
78 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
114 views

Calculating proportion of area covered by another layer - not just the intersection

This is a follow up question from $area gives NULL for some polygons in QGIS's Field Calculator and $area is NULL for over-wrapping geometry. I have a map of Cambodia at district level (dist) and ...
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18 views

There is Change in classification total area after Exporting and reclassifying it from **Google Earth Engine** to ArcMap

I have done classification of 6 classes in google earth engine on an available forest mask that has an area of about 2493 sq. km. The forest mask basically uploaded to Google Earth Engine and ...
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1answer
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Intersecting geometry sum - sharing the boundary count as intersection

This question stems from Calculating proportion of area covered by another layer - not just the intersection I have narrowed down the problem. I am attempting to find the percent of district layer(...
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1answer
3k views

How to calculate areas of land cover from a File System Raster?

I am using ArcMap 10.2. I have a raster displaying land cover. I also have a shapefile of polygons overlaid on top. I would like to calculate the areas of different land covers within the polygons. ...
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28 views

Calculating the area covered by isochrones in QGIS

I created isochrones using Iso-Area algorithm as polygons in QGIS. Is there any tool in QGIS that helps with calculating areas covered by created polygons?
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Find area of both sides [duplicate]

[![enter image description here][1]][1] [1]: Find area https://i.stack.imgur.com/Af6da.jpg https://i.stack.imgur.com/Af6da.jpg
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Is it possible to have auto-updating area fields?

I'm using QGIS 2.4.0 and I've noticed some problems with the derived area and the $area field. Firstly, I have a polygon which is a filled ring, inside another polygon. The derived area, and therefore ...
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1answer
66 views

$area is NULL for over-wrapping geometry

This question follows from $area gives NULL for some polygons in QGIS's Field Calculator. New question asks the same question as to why some area variables appear NULL. But the problem was resolved ...
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1answer
211 views

$area gives NULL for some polygons in QGIS's Field Calculator

I have the map of Cambodia(map) and the economic land concessions(elc). In trying to find the proportion of district covered by land concesions, I need the area variable. But when I create the ...
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6k views

Area of an irregular polygon using side lengths

I have only lengths for the sides of an irregular polygon, can anyone tell me how I can measure the area of the polygon? Remember only lengths of all the sides, no angles or coordinates. Few forums ...
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Getting polygon areas using GeoPandas

Given a GeoPandas's GeoDataFrame containing a series of polygons, I would like to get the area in km sq of each feature in my list. This is a pretty common problem, and the usual suggested solution in ...
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2answers
103 views

Using the field calculator to calculate intersections

I'm comparing several maps of one area (made by different people) to each other, and used intersection to find how much of specific selected features (polygons) overlapped. I soon realised that the ...
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1answer
412 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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3answers
1k views

What data projection should I use for area analyses in different countries at a global scale

I'm creating A4 maps to show where forest cover and mining fields overlap across the globe. Each A4 map focuses on a specific country (e.g. India, USA, China, Australia...). For each country, I need ...
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20 views

GEE create chart for the area of classified image

In Google Earth Engine I have classified a mosaic image using Random Forest, and using reducer the area of each class classified was determined by the code below. var area_classified = ee.Image....
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Convert SHAPE_AREA units via the REST FeatureServer API

All similar questions seem to involve desktop software but I'm strictly using the arcgis API like so: https://services2.arcgis.com/API_KEY_HERE/arcgis/rest/services/Category/FeatureServer/0/query?...
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2answers
74 views

PostGIS - Fast area computation on large overlapping (or not) polygon dataset

I'm co-developing an PostGIS based API that will work with complex and potentially large sets (>10k) of polygons, extracted from a large table following custom, user defined filters. I have ...
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1answer
37 views

Area commanded from given point

I want to define the area below a contour that slopes at a particular angle (say -0.05%) from a particular point, for many points. I have a DEM, and can compute contours at a particular level (say 200 ...
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Area given by software (QGIS and MapWindowGIS) DIFFERS from value given by revenue official [duplicate]

Revenue official has given area as 10.12 acres. I used QGIS and MapWindowGIS with projection UTM Zone 45 to measure area. The software gave area value of 13.06 acres. Why the difference?
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1answer
30 views

Area Difference - Attribute Table and Map

How can I setup plot areas to be identical in attribute table and map. In map and in attribute table I'm using the same " $area " designator. What's more interesting, the area of smaller ...
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27 views

Calculating snow pixels in GEE?

I have to calculate the decline in snow in a mountain area of Peru (between two points = two mountains). This is the link to what I have. https://code.earthengine.google.com/?scriptPath=users%...
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1answer
30 views

Combining parcels that are adjacent and add up to more than 10 acres

I am using ArcMap 10.7. My task is to find a site to be developed for parking. Sites are supposed to be greater than 10 acres. But we can also look at adjacent sites that add up to 10 acres. I read ...
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1answer
27 views

How to sum the area depending from another field value in field calculator?

I have a landcover-layer with an attribute of the administrative region (GEN). I am looking for an expression in the field calculator to calculate the summarized area depending on the GEN-field value. ...
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1answer
31 views

Getting $area from a feature in a processing script in QGIS3

I've created a complex process, but I'm stuck on one point. I found this code to find the number of features in a layer. def processAlgorithm(self, parameters, context, feedback): ...
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1answer
172 views

EPSG codes for projections to use when computing the area of global polygon sets in python env

The general answer to this question is "Use any equal area projection in units of meters that covers the world". Python code needed to make use of this is short and sweet: import geopandas as gpd ...
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1answer
9k views

Calculating geometry area in ArcGIS Desktop using ArcPy?

I have a polygon shapefile and I want to write a Python script to add a field named "area" and calculate its geometry areas. The script is like this: arcpy.AddField_management("...
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3answers
2k views

Calculating percentage of overlap of two layers in QGIS 3

I am trying to compare two different vector layers on QGIS 3. They are species distribution maps. I would like to calculate the percentage of overlap of two vector layers. My goal is to determine how ...
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50 views

Getting more accurate area size using QGIS

I'm using Natural Earth's shapefiles and try to match them to the real area size. I'm utilizing $area expression, but no matter what ellipsoid measurement I use the result seems to be very off. For ...
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1answer
35 views

How to calculate the area of each WRB soil class with the 2017 TAXNWRB_250m raster?

For my research I want to calculate the total area of each WRB soil class on each continent in km2 using the 250m WRB soilgrids raster. However, the total area I calculated is almost 1.3 times as ...
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1answer
103 views

Adding column with area values in attributes table with standalone PyQGIS

I would like to add an area column to the Attributes table using Python. I prefer not to use QGIS Python console. I would like to do that using cmd. How should I change my code? My code and error ...
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1answer
35 views

Different styles of area in same shape layer

I'm using QGIS 3.16. I have the following problems: One of my shape-layer has several areas. Now I want to give every area a different style/colour. I already found the function to give all areas the ...
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18 views

Is it better to calculate area of a global raster using long/lat or using an equal area projection (e.g. Galls-Peters)?

I am trying to calculate the area of values in a global spanning raster with values of NA, 1, 2 or 3. I would like to know the total area of each category, however, the map is currently in lat long (...
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29 views

Editing areas in shapefile + scalebar

I´m using Qgis Version 3.16 I have the following problems: One of my layer has several areas. Now I want to give every area a different style. I already found the function to give all areas the same ...
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1answer
28 views

Calculating area of from 10x10 degree tiff raster file using QGIS

I am new to QGIS. How do I calculate the area in 0.05x0.05 cells from a 10x10 tiff raster file? I guess I will have to do a loop function to get the areas from the 10x10 file but I have no idea how to ...
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1answer
453 views

QGIS - processing area and calculating volume of polygon with know elevation from a DEM

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) ...
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1answer
51 views

$area is not returning the correct value in QGIS

I'm working in a black QGIS project set to EPSG:27700 and a layer in EPSG:2770. When I measure the area of a polygon using the measure tool I get a value of 7594315ha. When I subsequently do this in ...
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1answer
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Overlapping score for each feature in the merged layer after spatial joins

I've clicked on the Join attributes by location button and can join two layers. But in the merged layer, how do I find out percentage of overlap/intersect calculated for each feature? For example, in ...
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1answer
98 views

Working out percentage of polygon covering another using PostGIS [closed]

I have 2 polygon tables, polytable_a and polytable_b. a has 1000s of features and 100s of unique names (a1, a2, a3, a4.... etc) assigned to the polygons. b also has 250,000 features but only 3 unique ...
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2answers
115 views

ST_Area(geometry) with ogrinfo estimates a stable area per grid cell

I use ST_area(geometry) in order to calculate the area of each grid cell of a vector grid with LCC projection and 6x6km2 resolution. The CRS of the vector is: +proj=lcc +lat_1=45 +lat_2=22 +lat_0=38.7 ...
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1answer
552 views

Calculate area of polygons in square meters when CRS is EPSG:25833

I have EPSG:28533 coordinates and would like to calculate its area in square meters and then transform these coordinates to EPSG:3857. I have taken the code from here to calculate the area but it does ...
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2answers
108 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
83 views

Finding area of polygons within buffer [duplicate]

I have 102 different sites in two cities, which I have created buffer zones for. I also have layers that have polygons for different landscape features (e.g. water surface area). I am trying to find a ...
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1answer
103 views

Calculate area with a buffer

I am looking for help for my master thesis. I have two layers, a set of households and burned area (vector data). I created buffer zones around each household and now want to estimate the burned area ...
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1answer
242 views

Calculating area in the attribute field of a QGIS 3.4.3 project with multiple CRS

The area calculations in my project derived from the attribute field show values way below actual area, because the attribute field assumes the project CRS (EPSG:3857). However, this CRS should remain ...

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