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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7
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2answers
18k views

How to calculate 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 length of the perimeter of each polygon?
11
votes
5answers
9k views

How can I measure area from geographic coordinates?

If I have polygons in geographic coordinates (WGS84), how do I measure the total area each takes on the surface of the earth, taking into account the curvature of the earth?
5
votes
2answers
2k views

How to calculate area of 1 x 1 degree cells in a raster

I have a simple array (not geo-referenced in any way) in Matlab (which is not a language I know a huge amount about...so I can export it to other languages if needed) which has the dimensions 180 x ...
6
votes
1answer
1k views

How to calculate te area between contour lines on a DEM with QGIS 1.8?

Does anyone know how to calculate the area in km² for each altitudinal band (between 100 and 200, 200 and 300...) based on a DEM? I added the contour lines with a distance of 100 metres but could not ...
9
votes
7answers
10k views

How to remove only donut holes from polygons using ArcGIS Desktop?

I am using ArcGIS Desktop 10.0. I have a trick for removing the donut holes, which is converting the polygon to line and then creating polygon out of the lines and in the end merging all of them. ...
2
votes
1answer
1k views

Calculate area weighted average of attribute in one layer by shape in another

For a project I am working on I would like to intersect fire station response districts with income data to determine the median income per response district. However the borders of the layers ...
2
votes
1answer
3k views

Convert area from square meters to degrees globally

I have a global raster file with 3600x1800 pixels. I don't have any information about the projection used. The raster contains one band with a quantity with the unit "per square meter". How can I ...
5
votes
2answers
5k views

Converting Longitude and Latitude Coordinates to Square Miles?

I have a set of Long and Lat co-ordinates making up a five point polygon which I have converted in excel using the following formula: ...
4
votes
2answers
2k views

How to find the area of raster values within polygon zones?

I'm using ArcGIS 9.3 and I just can't seem to get this right - I've tried tabulate areas, zonal stats, converting to polygons, etc. I'm missing something somewhere. I have a USGS impervious surface ...
3
votes
2answers
2k views

How to calculate the area of rasters in QGIS?

I have been working with some rasters and would like to know how to calculate the area occupied by one element of a raster in Qgis.
1
vote
3answers
9k views

How to calculate a percentage of an area covered by polygons ArcGIS 10.1

I created an Aspect Layer with 9 Zones on which I want to use the Tabulate Area Tool with another polygon layer namely Woods. So what I actually need to know is the percentage, covered by woods for ...
0
votes
2answers
38 views

Group points and compute area

In a point vector layer, how to compute area for 4 defined ranges of values of one attribute? On the example below, I want the total area for each of the 4 colours.
7
votes
1answer
10k views

Calculate area within Python script in Arcmap

I am trying to calculate the area of a polygon within my Python script. I create a new polygon from merging two together, and I'd like to add the area of the resulting polygon to a field in the output ...
3
votes
1answer
2k views

Calculate polygon area inside extent

We're using ArcMap 10.0 sp5, creating a tool in c# using the ArcObjects sdk. Is there a built in function or simple set of steps that calculates the area of each feature of a polygon layer within a ...
3
votes
3answers
2k views

Auto-calculate field (area or formula)

I'm wondering if anyone has any insight into the potential to auto-calculate the value of a field, either area or distance (ideally) or a formula (based on the values of say 2 other fields, or an ...
3
votes
3answers
15k views

Calculate projected area of polygons with field calculator in ArcMap 10

I've got a polygon featurelayer in arcmap. The coordinate system of the featurelayer's featureclass is web mercator. The dataframe of the map uses an equal-area projected coordinate system. I've ...
6
votes
2answers
383 views

Deleting polygons smaller than certain dimension using ArcGIS for Desktop?

I've made a model in modelbuilder in Arcmap 10.3, what it basically does is creating polygons over open areas such as farm-lands, grass-lands, marshes etc that has a low slope. My challenge is that I ...
6
votes
2answers
1k views

PostGIS - area-weighted calculation on an intersection

I'm trying to learn postgis sql by performing some familiar operations from ArcGIS. Here, I want to perform an area-weighted calculation of certain populations on the intersection of a set of parcels ...
3
votes
2answers
709 views

Determine density or cover from a raster layer that has been clipped by a polygon

I am a very new GIS user using ArcMap 10. I have a raster layer of tree canopy that I have clipped so that the layer is in a polygon that is a circle with a 2km radius. I have done this for four ...
1
vote
1answer
131 views

Calculate area intersected areas, problem [closed]

(I'm working in QuantamGIS) I intersected two layers creating a new layer. Within the attibute table of this new intersect layer i would like to calculate the new areas. However, it just doesn't ...
3
votes
1answer
174 views

QGIS 2.6 summarizing area (m²) for current atributes

If I have a code for each polygon and I have counted the area in m² for each of them (all this information is in single columns). How can I summarize these areas by codes (for example summarize all ...
2
votes
2answers
2k views

How to calculate volume from a raster file?

I have a raster file containing the depth of water. I need to find the volume of water using that raster file. I need to find the area of each cell and multiply with the depth. How can I do it in ...
0
votes
1answer
97 views

Cannot obtain correct area values *With* correct projections

I'm trying to get the percentage of each U.S. county overlaying groundwater (data from the census and USGS respectively). They're both polygons. I have 1) correctly projected the data and the layer ...
15
votes
2answers
6k views

Is it possible to gray out a Google Maps map except for some area?

What i am looking for is a way to emphasize a certain area on a Google Maps map by graying out the rest of the world. I heard about some solution of using 2 polygons of which 1 is visible and the ...
6
votes
1answer
7k views

How to measure area correctly?

I have now used my entire evening, but I can't figure out how to make areal calculations (eg. in km2). I have tried the 'field calculator', I have tried the 'measure area' function on the "attributes" ...
3
votes
3answers
751 views

Determining the area of each polygon within a polygon boundary?

I have a series of maps representing a 1000m diameter around a point. These maps contain 40 different types of polygons that represent a land use (ex. Corn crop, Pasture). I want to select all ...
3
votes
2answers
9k views

Cannot get areas for polygon layers in ArcMap 10

For an ArcGIS project opened in ArcMap 10, we have added polygon layers representing different geographical features. After all the polygons were created, we opened the attribute tables for those ...
8
votes
3answers
2k views

calculate area of vegetations in a raster file

How do I calculate area of several vegetation types in a raster (.img file type) image. They are color coded. Am using QGIS (1.8.0) and ERDAS 9.2.
8
votes
2answers
1k views

Projections appropriate for global analysis that preserve area and that preserve distance (but not necessarily in the same projection)

I am looking for a projection (or a set of projections) that decently preserve distances so that I can buffer every country in the world and have a similar level of minimal distortion for each. I ...
7
votes
3answers
5k views

How do I get the area of a WGS84 polygon in square meters?

The following gives me the area of the polygon in square degrees: SELECT ST_Area(ST_GeomFromText('POLYGON((871325.790874952 6105405.3261047,871418.748307692 6105359.72944624,871346.22022442 ...
7
votes
2answers
4k views

How to split an irregular polygon into equal areas?

I am a surveyor and use QGIS for maintaining soil test records on civil projects and am constantly provided with test lot area or number of lots required. These are more often than not irregular in ...
7
votes
2answers
1k views

How to get correct area calculation using Google Mercator?

i use QGIS with openlayers-plugin and i´ve loaded google satellite as a layer. what i want to do is making a shape-layer (polygon) with the goal to get the area values of the polygons. i´ve activated ...
3
votes
1answer
2k views

How can I get my Qgis area calculations in metres rather than degrees? My shapefiles are projected using WGS 1984 UTM fuseau 35 Sud

I am using Qgis 1.7.4 to calculate the area of polygons. My shapefiles have been projected using the coordinate system WGS 1984 UTM fuseau 35 Sud, but my area calculations are still displayed in ...
2
votes
0answers
130 views

Raster area (QGIS) problem explained

I would like to know the area that each value in a raster has... The raster I have has values from 2-15 and I would like to know the area that each value is occupaying within my polygon... Thanks! I ...
0
votes
1answer
450 views

QGIS: Multiply Raster Value with Pixel size

i'm working on a map with population densities. My raster data contains values as [People/square meter] for each cell. I have per capita values of energy demand etc. which I want to multiply with the ...
8
votes
1answer
282 views

Circle area calculation in QGIS is inaccurate

I created a circle with a radius of 3 km, calculated the area using field calculator and got a different result from real area. The QGIS result is 28273078.8 while manually calculated area is ...
7
votes
1answer
424 views

How do I represent the whole Earth as a Polygon?

This is related to determining the interior of a Polygon. My difficulty is that if I specify a Polygon covering the Earth going from East to West, it will still have a boundary along the ...
6
votes
2answers
734 views

QGIS area calculation differs when on the fly CRS transformation enabled

When I open QGIS, add the layer, and calculate the areas of the shapefile via field calculator I get a different area than when I open QGIS and check "Enable on the fly CRS transformation" and ...
6
votes
2answers
530 views

Wrong $area from field calculator (QGIS)

The area of the polygons in a layer, calculated by the field calculator with "$area" is wrong (much too big) for some polygons. If I draw the concerned polygon again, the area is calculated correctly. ...
5
votes
2answers
2k views

Shapefiles for U.S. Area Codes (NANP)

I have a bunch of telephone numbers (just the area codes), and I'd like to geolocate them and make a map, but I haven't had too much luck googling for shapefiles for Area Codes. Surely these are in ...
4
votes
4answers
8k views

How to recalc WGS84 Shape_Area field to square miles in ArcGIS 10

What are the units of the Shape_Area field in a wgs84 feature class? Is it decimal degree squared? I would like to convert that to something more meaningful like square miles without reprojecting the ...
3
votes
0answers
308 views

Why does field calculator compute area in square meters?

I am using EPSG:102748, and have set my Settings/Option preferred measurement units to ft. My CRS is NAD_1983_StatePlane_Washington_North_FIPS_4601_Feet, and when I use the measure tool, it returns ...
3
votes
0answers
124 views

Calculating length of road network within a polygon [duplicate]

I have a road network stored in a gdb and some polygons in another gdb. I want to populate an attribute for each polygon with the total length (in km) of the road network that it overlaps. Any idea ...
3
votes
3answers
373 views

Calculate the majority of one polygon in another (fishnet)

I am looking for a method to calculate the majority of one polygon file (a map of ecoregions) in a sampling grid (fishnet) in ArcGIS. The purpose is to assign each sampling grid (fishnet) to an ...
3
votes
3answers
5k views

Setting default units for Shape_Area to be Acres using ArcGIS Desktop

When I create a new feature layer polygon, how do I set the default in Shape_Area to read out in Acres?
3
votes
2answers
951 views

How are service areas created in ArcGIS Network Analyst?

I want to create a service area map of Burma in order to spot the areas that are within xx kilometers from a set of cities. The problem is that the generated polygons aren't exactly what I expected. ...
3
votes
2answers
906 views

How calculate areas between certain contour lines in qgis? [closed]

How do I calculate the area between certain contour lines (e.g. 0-800, 800-1400, 1400-2100...) from a given shape file. What I need is the area of the the certain elevational levels. shape file is ...
3
votes
1answer
834 views

How to exclude some parts of raster classes based on size of area?

I have a raster file with 5 classifications. I've calculated area for all of the classes via Zonal geometry, Arcmap 10. Now, I want to exclude patches which are smaller than 100 sq. km. and ...
3
votes
1answer
221 views

Compute global DEM topographic indices and compromise projections

I would like to compute global topographic indices based on SRTM elevation data. These indices are computed along river/channel networks extracted from a DEM and are a functions of both local slope ...
2
votes
3answers
586 views

Summarize the total area of land use polygons within map sheets - how?

I would imagine that at least some of you have encountered similar problems to mine and I´d like to hear how you solved them. I have a map sheet index (a grid as a shape file) covering a large area. ...