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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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23 views

Determining the area in Sq Miles of 1 polygon that are contained completely within another polygon

I am looking to determine how much of the area of 1 polygon (Lets say a body of water for instance) falls completely with in another polygon (Call it a state or county for instance) i have a layer ...
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49 views

Where can I find the legend?

I have downloaded the following two tiff files from here: pnv_biome.type_biome00k_c_1km_s0..0cm_2000..2017_v0.1 pnv_biome.type_biome00k_sse_1km_s0..0cm_2000..2017_v0.1 Using r.report in QGIS 3.6 I ...
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33 views

Water area trend, Google Earth Engine?

I've written this code for water area trend in Google Earth Engine. However I don't know is the final result true or not? Could anyone check it, please? Code link: https://code.earthengine.google.com/...
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41 views

How to create a function for getting a largest polygon from 2 polygons using case statement in PostgreSQL?

CREATE OR REPLACE FUNCTION public.largest_polygon1( geom1 geometry, geom2 geometry) RETURNS geometry LANGUAGE 'plpgsql' COST 100 VOLATILE AS $BODY$ begin Return Case ...
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1answer
60 views

Adding Area column in Polygon layer using PyQGIS? [closed]

I have a WardBoundary.shp file with Polygon Features in it. I have to calculate the area of each Polygon and write into attribute Table. I can do manually by using '$area` but I need to automate ...
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16 views

Raster of land area within 15 km radius

I have two polygon layers, one of Land and one of Reef. I would like to create two rasters, of the Reef layer, who's values are the area of Land within 15 km of each cell, and the area of Reef within ...
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2answers
28 views

Calculating areas in continuous raster of flood map?

I generated a flood hazard map (raster) of a certain area using ArcGIS 10.5 and classify the result into low 0.1 ÷ 0.5 medium 0.5 ÷ 1.5 high > 1.5 After that, I overlay a Land Use map (...
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69 views

What causes difference between two sources?

I have downloaded ESA global land cover tiff file and opened it with QGIS 3.6. To measure Africa separetly I used polygon file of this continent as a mask. I got the result that total area of Africa ...
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1answer
55 views

Measuring area using correct CRS and units in QGIS

I have uploaded a shapefile and I am simply trying to calculate some simple areas of provinces (and I know their areas from Wikipedia). My map is from Zimbabwe, and I have saved the project, ...
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18 views

Doing large calculations using Export in Google Earth Engine?

I need to calculate builtup and nonbuiltup area for the complete country on India. The following code gives a "computation timed out error". var geom = India.geometry(); var area_classifyed = ee....
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1answer
58 views

Same equal area projection results in different areas when shifting the center of projection

I found that using an equal area projection results in different areas for the same polygons if you shift the center of projection (ie to minimize the distortion of your area of interest when you ...
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1answer
34 views

QGIS 3.4 $area not equal for same shape

First, I created a regular grid of the size 1km^2 (epsg: 2056). Then I calculated the area of of this grid using different GIS: Python: arcpy area_arc # Python Setup import arcpy arcpy.env....
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1answer
20 views

Select By Attribute - Get Parameter as Text - User input SQL ArcPy

I am trying to create a script that will search for suitable site locations. I want to let the user input an area size (e.g. >20) to be searched but each time I run the script it comes up as Error ...
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1answer
35 views

Understanding difference between area calculation when using zonal statistics tool and identify button?

I am working in ArcGIS Desktop 10.5 and I am a beginner. I have very basic, non-overlapping polygons over a raster that represents bathymetry data. I need to figure out various statistics about each ...
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1answer
60 views

Knowing/converting AREA, PERIMETER units in QGIS?

I use Convexhull tool in QGIS and there are result value : AREA = 0.0017494390 PERIMETER = 0.1725495172 I thought the result was strange. So, I took a rough estimate of the points through the ...
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1answer
37 views

Calculating area difference between two polygon shapefiles using QGIS

I have two polygon shapefiles which contain about 30 features. These features have different boundaries in both shapefiles so the areas are different too. I want to calculate that difference in the ...
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95 views

Doing change detection of land cover between 2 landsat images in google earth engine?

I am doing land use/ land cover classification of 2000 and 2018 year . I had completed supervised classification now i wanted to do change detection analysis. Please guide me how to do change ...
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0answers
70 views

Converting Google Maps Lat Long to Square meter area

I want to convert a set of 5 Lat Long (Directly taken from Google Maps) into Sq Meter area. As 5 points are there I have found the formula on Converting Longitude and Latitude Coordinates to Square ...
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1answer
33 views

How to smoothen and dissolve the output image and how to calculate the pixel areas of different classes in Google Earth Engine? [closed]

I am doing supervised classification of 5 different classes, I tried the code suggested in GEE tutorial but I can't able to understand the way they did. I am attaching my code here. Could someone ...
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0answers
41 views

Calculating the area of raster within polygon

I have a raster layer with values of energy demand in each cell. I would like to know the area of the raster within each polygon (see screenshot). Any suggestions on a simple approach for this?
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41 views

Calculating damage from a flood at the village level in percentage

I am using ArcGIS for my analysis. I want to calculate the damage from a flood at the village level in terms of percentage area damaged. I have done the following steps. My village file is in point ...
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1answer
38 views

Calculating the area of one layer inside area of another layer QGIS [duplicate]

I am currently looking at some Marine Protected Areas (MPAs) in Madagascar, and am trying to work out the percentage reef cover inside an MPA boundary. For example (in the picture below), I have the ...
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0answers
40 views

Area of one raster cell

I need to identify the area (m2) of each cell in a raster layer. I do know how to find the cell size under metadata (which in my case is [0.00980834,-0.00748333]); but how do I convert this into m2 or ...
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1answer
68 views

QGIS Identify feature Cartesian area in degrees

In QGIS 3, the identify feature tool automatically calculates area. However, there are two areas: Cartesian and ellipsoid. The first is being calculated in degrees (not wanted) and the second in ...
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1answer
13 views

Calculating fraction of area characterized with certain values?

I have a rasater data with cell values of the following: missing, 1, 2, 3, 4, and 5 Now I need to find the fraction defined as (area with value 5)/(Sum of areas with values 1,2,3,4) for a certain ...
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1answer
205 views

Surface area calculation in Google Earth Engine?

Using this code, I've extracted water extent in a Landsat median image. But how can I compute water area extent? code link: https://code.earthengine.google.com/8ad84d9ca59b3cb71b62f83119621bdc var ...
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1answer
91 views

Calculating area by classified image in Earth Engine

I want to calculate the area for each classified color in earth engine. Here are my codes. var image = ee.Image(ee.ImageCollection('LANDSAT/LC8_L1T_TOA') .filterBounds(roi) .filterDate('2015-01-...
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1answer
55 views

Customized Albers Equal Area Conic projections are cosmetic only or do they affect area calculations too?

I will be doing area calculations for 100+ countries using country polygons taken from GADM, a database of global administrative areas. I am using ArcGIS. The GADM data is in WGS84 and is unprojected. ...
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1answer
61 views

Getting the percentage area of intersecting polygons [closed]

I have the polygons for census tracts within New York City. I also have the polygons for the parks. What I would like is % of the census tract area, with an added 400 meter buffer, that is park. I'm ...
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0answers
26 views

How to compare centrality of points in different shaped and sized polygons

Suppose I have several polygons of varying shape and size, each containing a single point. I want to compare the centrality of each point, and determine which point is more central to its polygon. I'm ...
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22 views

Using ST_Area(geography) with ogrinfo in command line?

I want to to calculate the ellipsoidal/spheroidal area of each grid cell of a vector grid using ogrinfo. When using ST_Area(geometry) I get the 2D planimetric area (which seems to be constant for a ...
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2answers
113 views

Turning degrees into square kilometres (km2)?

After running raster layer unique value report I have got pixel number and area in degree. How can I turn it in square kilometres (km2)?
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1answer
48 views

Comparing Tract-level data to State-level?

I'm using firearm trace data (available at the state-level) and attempting to compare it to socially disadvantaged areas (census tracts) by the way of regression analysis. Katz and Schnebly (2011) ...
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1answer
52 views

Search plot by total area of two adjacent plots

I've got some QGIS data where each plot is described with some attributes e.g. Shape_Area which is the field describing the area of plot in m2. Normally I search for plot using the expression e.g. ...
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1answer
49 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
52 views

Wrong/Different values from $area and Group Stats

As mentioned in other questions there seems to be a problem with $area when OTF is enabled. In QGIS3 it can not be disabled My project hast EPSG 31255, some layers area 31255 some have different crs....
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2answers
51 views

How to convert point data to different sized polygons representing Marine protected areas?

I am trying to map Marine protected areas. I have collected data of where all these areas are. The data is expressed as point data (seen within the top image). Within the attribute tabled I have a ...
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10 views

When tabulating area zone field doesn't populate in .dbf table

I am using the tabulate area tool to calculate area of habitat types around banding sites. Each site has a unique name, so I used that when selecting my zone_field in the tool. However, when I run ...
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0answers
42 views

Why are my polygon features area being calculated as zero?

I am trying to measure the area of polygons within a larger polygon. However some of them, seemingly without reason are being calculated as having zero area. The highlighted regions are calculated as ...
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1answer
101 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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0answers
77 views

Intersection and area calculations in geographic vs. projected coordinates

I think one should do intersection calculations when layers are in the same coordinate system, and one should do area calculations in the appropriate projected coordinate system. The order matters, ...
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1answer
81 views

QGIS shows incorrect $area in label, but correct in field calculator

I tried showing $area of polygons in QGIS, and it always showed planimetric square degrees instead of metric units. No matter what I set in project general settings, the value remained the same. ...
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1answer
42 views

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
45 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:...
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1answer
84 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 ...
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0answers
42 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
58 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
71 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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1answer
120 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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1answer
184 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 ...