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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Python equivalent to QGIS Raster Surface Volume Tool

I've been using the QGIS tool "Raster Surface Volume" https://docs.qgis.org/3.22/en/docs/user_manual/processing_algs/qgis/rasteranalysis.html#raster-surface-volume to calculate the volume ...
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-1 votes
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How do I get the area of a cross section in HEC-RAS?

I am done with steady flow analysis and would like to estimate the volume of the flood. How will I get the area of a cross-section?
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Area calculation for non-planar surfaces

I am looking for a way to calculate the area for a big set of 3D-surfaces. I know, that some of those surfaces are slightly non-planar, which means that the coordinates got somehow "rounded" ...
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Road network analysis for big data

Is it possible to generate service areas from 65000 facilities? Batch processing or database analysis? A friend tried with 6000 (1/10) facilities, OpenStreetMap data (country Latvia) to calculate ...
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1 vote
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Calculating volume of IDW raster below Height of Plane, but it is failing

I am using ArcMap. I am trying to calculate the volume of water using IDW Tool. When I reach a point to calculate, the statistics below height of plane cannot run, giving me 0.00, What could be the ...
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2 votes
1 answer
137 views

Why are my area calculations in Python so small with .area()?

I'm trying to calculate the area of a flood with Python, but the results seem way too small: iceye_breaks = iceye_breaks.to_crs("+proj=cea +lon_0=0 +x_0=0 +y_0=0 +lat_ts=45 +ellps=WGS84 +datum=...
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4 votes
1 answer
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Which projection type is most suitable for area calculation of northern hemisphere using arcgis/qgis?

which projection will be most suitable for the area calculation of polygon which is almost covering the whole northern hemisphere? I am trying to calculate the area of the historic distribution of ...
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1 vote
1 answer
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Comparing polygon areas across simple feature collections

I currently have three simple feature objects created from different shapefiles in R using the sf package. These three objects have all been projected to the same coordinate system using st_transform()...
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Calculating area of habitat suitability map obtained from Maxent using ArcMap

I am doing a species distribution modelling using Maxent. I got the species distribution maps from maxent and I reclassified the map into four group as high, moderate, low and unsuitable areas in ...
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1 vote
1 answer
22 views

Dissolve a intersection along id and keep only features of the bigger area QGIS

In QGIS I'm trying to dissolve an intersection and keep only the features with the bigger area [blue arrow] (compared with other features with same id [red box]). I'm interested in keeping other ...
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4 votes
1 answer
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Incorrect ST_Area after changing to 4326 in PostGIS

I'm trying to change the geometry in our database from 3857 to 4326 so that I can use more functionality within PostGIS. It converts them all properly when I run the alter column and transform query: ...
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5 votes
2 answers
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Getting "QgsPolygon: CurvePolygon EMPTY" when extracting the largest part of MultiPolygon using PyQGIS

There is a shapefile with MultiPolygons, see the image below With this code, I am trying to get the largest part (by area) of each MultiPolygon feature. It utilizes the constGet() method. layer = ...
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Dissolving features based on another layer in QGIS

I have two layers, see image below: Yellow: the ground where people can build; Red: existing buildings. Create a shapefile of all grounds where >50% of the grounds are free. In order to do this, ...
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2 votes
1 answer
79 views

Finding correct ellipsoid to calculate the surface of polygons (hectares) in QGIS

I would like to calculate the surface of a group of polygons in QGIS. It was not me to create the shapefile, when I add it to the project and I check its properties, it results that the geometry and ...
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Calculate cell/pixel area with Rasterio in Python

The Situation I have a tile spanning 10° north-south (n-s) and 10° east-west (e-w), e.g. from 10-20W and 10-20N. This tile contains multiple pixels, e.g. with a resolution of n-s and e-w of 100m at ...
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r.surf.area outputs are unclear (QGIS)

For different projects in my company the area was calculated using $area (and sometimes area($geometry) in the Field Calculator. I decided to change the surface area calculation to using the r.surf....
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How to get a list of the empty areas between the filled ones? (+size in ha)

I am an absolute beginner in GIS software. My goal is to get a list (or something similar) of all the empty polygons/areas between the colored ones. It would be perfect if the size and location of the ...
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1 vote
1 answer
53 views

Area based Heatmap (QGIS)

I am new to QGIS. I am trying to create a heat map based on area not points. What I want to acheive is similar to this question. I want to create a binary raster (0 for no point, 1 for point). Then, ...
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0 votes
0 answers
49 views

How to import CAD drawings into QGIS?

I have a dxf with a polygon. This polygon has an area of 680279.678 m² in Autocad. When i import it into QGIS and calculate the area in the field calculator with area($geometry) i get 680281.25 I ...
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Computing area of very large feature collection in GEE?

I'm trying to calculate the total area of a very large Feature Collection (over 1 million features) of burned areas over the Amazon. I want to find the total area (sum), and also the area grouped by ...
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3 votes
2 answers
152 views

Getting area of part of MultiPolygon in QGIS

Is it possible, with QGIS, to get the area of a single part of a multi polygon? Or do I have to split them into single polygons?
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3 votes
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Calculating area with formula gives zero in the attribute table in QGIS

I am trying to calculate the area of each patch of a vector on the total area of all my vectors (sum of each area) with the following "area" / "totalarea" but then it returns 0, ...
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  • 399
5 votes
1 answer
91 views

Draw buffer around points considering slope in QGIS

I generated random points on a map. Around each point I would like to draw a circular buffer which considers the slope in that area, and within these circular buffers I would monitor tree height in ...
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Calculating area of polygon with consideration of slope in QGIS [duplicate]

I would like to know if there is an easy/efficient way in which you can calculate the area of a polygon considering the irregular slope underneath the polygon. I would like to know a solution in QGIS.
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Do you need to factor in projection into area calculation in Google Earth Engine (GEE)?

I'm interested in calculating the area I have classified of a certain class. Do you need to account for projection to assess class area or can you run the following code and it will be accurate? I'm ...
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0 votes
1 answer
35 views

Convert unit of measurement for a buffer area

I have generated buffers around geocoded points on a map. The shape areas for buffers are clearly different than the shape areas generated when projecting polygons (such as tracts, CDPs, or counties). ...
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5 votes
1 answer
73 views

Raster classes area calculation

I have 3 raster layers each of them is classified into 4 classes and each one has defined weight value. I had to to create FINAL raster by multiplying those 3 rasters with their weight values and ...
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0 votes
0 answers
24 views

Getting width or area of line objects obtained from OpenStreetMap

I want to get width or area of the road data in OpenStreetMap. All of the road data from OSM are lines, so I cannot get the width or area info of these roads. If these were polygon data, I would have ...
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How to know if a reverse-geocoding place is a city or village/town

I need to create a reverse geocode logic that is able to determine if a place is a city or a village. I don't want to use GoogleAPI, so I searched for other API-provider: locationiq.com developer....
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1 vote
1 answer
161 views

How can I calculate the area of a 5-arcminute grid cell in square kilometers, given a known latitude and longitude? [closed]

I am trying to compute the area of a 5-arcminute grid cell (coming from a global dataset) in square kilometers given a known longitude, latitude. I was able to compute the vertical length of the grid ...
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Merging queries to return ways/nodes that are within relations matching criteria using Overpass API

Motivation - I am currently processing a number of relations matching criteria and then doing an additional query to get all the ways/nodes within those relations. . Goal - I'm trying to simplify this ...
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38 views

Excluding nodes in ways that are outside of intended area using Overpass API

The documentation for overpass states Nodes are found if they are properly inside or on the border of the area. Ways are found if at least one point (also points on the segment) is properly inside ...
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2 votes
1 answer
28 views

QGIS 3.8.3 - Create polygon with a specific width

I'm very new to GIS and QGIS. I'm trying to map areas of arable fields and would like to create a polygon that traces the edge of a field and is a specific width away from the edge of the field ie 8 ...
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0 answers
32 views

Calculating polygon areas using Field Calculator in PyQGIS [duplicate]

I am trying to calculate areas for polygons in QGIS 3.16.10 using PyQGIS 3 as you would with the Field Calculator. I am trying to use QgsExpression to create the necessary expression. However, the API ...
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2 votes
1 answer
73 views

Divide spatial hexagon in equal areas (pies) in r

I have a grid of hexagons that is being used to create a model per hexagon. I would like for each hexagon to be divided into 3 or 6 equal areas so that I can use 2/3 of the hexagon total area to train ...
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2 votes
1 answer
43 views

PostGIS equivalent of Pandas geometry.area for square feet

I have a Python script that has a line that takes the geometry and calculates it into a square feet value by multiplying the area by 10.7639 in a geopandas dataframe. bldg_feat_poly_df['bldg_sqft'] = ...
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1 vote
2 answers
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Habitat area within UTM grid in PostGIS

I'm using PostgreSQL 14.1 with PostGIS 3.1 and I've got two tables malla, that contains a UTM grid of 10x10 km, and CLC18, that contains the habitat polygons of the Corine Land Cover project. Now I ...
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  • 2,271
1 vote
1 answer
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Select polygons that are within other polygons and have a certain area in PostGIS

I'm using PostgreSQL 14.1 with PostGIS 3.1 and I've got two tables malla_p and pen_bal. I want to select those polygons of table malla_p smaller than 10,000 ha that are within the polygons of table ...
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2 votes
0 answers
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Area calculation in PostGIS

I'm using PostgreSQL 14.1 with PostGIS 3.1. I've got a UTM 10x10 km grid malla, set in EPSG 25830, that covers all Spanish territories: I have run the following code (just to check that everything is ...
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3 votes
1 answer
48 views

Creating field with difference between areas of two layers in QGIS

In QGIS how can I get the difference between the areas of two layers through field calculator? And is there a way to automatize it so every time a new feature is added the difference updates? Layer 1 ...
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  • 1,054
2 votes
1 answer
245 views

Dividing polygon into given number of equal areas in OpenLayers

I'm using a Style with Stroke and Fill to have something like this for Polygon: const feature = new Feature( new Polygon([ xPos.map((x, index) => { return transform([...
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1 vote
0 answers
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Calculating area of single class in Google Earth Engine

I'm doing a research about evaluation of the effect of catastrophic forest fires in Yakutia in 2021. I did some classification of three different classes: 'burned_area', 'vegetation' and 'water'. Here'...
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0 votes
0 answers
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Updating fields automatically in attribute table [duplicate]

I am working in QGIS 3.16 and I would like to know if it is possible to automatically update the fields. For instance I have a polygon shapefile with a field that indicates the area. I used the field ...
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5 votes
4 answers
815 views

Calculating polygon area within other polygon using GeoPandas

I have a polygon GeoDataFrame 'Polygons' with attribute "AREA" (total polygon area in ha) and another GeoDataFrame 'Small_polygon' with smaller polygons within the 'Polygons'. How do I ...
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4 votes
5 answers
536 views

Calculating polygon area in QGIS without adding new field

Is it possible in QGIS to quickly calculate the area of a polygon using a Processing tool, plugin, script without adding attributes or creating a new layer? Something launching the results window or ...
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0 votes
1 answer
24 views

Google Earth Engine - Area is undefined to used in if

I'm having trouble getting my if to recognize the value of the area. When utilize .type returned undefined Code doesn't return response I tried: ee.Number .float .int var ar1 = a1.area(); var ar2 = a2....
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7 votes
2 answers
126 views

Classifying raster layer by number of equal values in given area using QGIS

I am using QGIS 3.16.12 - Hannover. I have a binary raster layer which consists of 2 values, either 0 or 1 (in my screenshots, 0 = black, 1 = white). The 1 values are scattered throughout the layer in ...
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1 vote
0 answers
254 views

How to calculate the area of a polygon in real meter in OpenLayers?

I'm trying to figured out why I'm getting weird results from ol/sphere/getArea. I draw an rectangle with fixed size of 5x5 meter. To translate 5 meters to map units, I do the following: const factor = ...
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  • 391
1 vote
1 answer
106 views

How to create a histogram of areas of clustered S1 image in Google Earth Engine?

I am using S1 images and clustering in Google Earth engine to identify different land uses. I clustered using ee.Clusterer.wekaKMeans(5).train. Now I want to create a histogram that shows the area per ...
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1 vote
1 answer
45 views

Calculate within a buffer around a point the % of area covered per category

I have to calculate within a buffer of 10 m around each sensor (and later 50 m, 100 m, 100 m...) how much % of the area in that buffer is covered by each Landscape Element (LE). The goal? An attribute ...
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