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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6
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1answer
3k 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" ...
2
votes
2answers
474 views

How to single out country data from a world data map?

Say that i have two "data sources"; A global map of average wind speeds, A shape file (or similar information) of all country borders in the world. How do i combine these two sources and extract ...
1
vote
1answer
257 views

Summarize polygon area using another polygon

I have a shapefile representing public/private lands in Montana. This is a multipart shapefile where I've simplified attributes so that #1==private and #0==public. Next I have a shapefile of ...
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vote
1answer
355 views

ESRI android SDK Calculate area in square meters from polygon geometry

Hello I have a Polygon object in ESRI Android SDK that I'm creating on a map, I would like to calculate that polygon object to square meters. currently I use double area=polygon.calculateArea2D(); ...
3
votes
1answer
1k 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
115 views

GeoTools, add column in query with CQL

I'm trying to query the database (DataStore) and want to let the datastore calculate a value for me. In SQL I would do it like this: SELECT name, ST_Area(ST_Intersection(the_geom, ....) AS myValue ...
2
votes
0answers
765 views

How to calculate the area of a polygon considering the relief?

I work in a fire department and i'm mapping all the fires that occur in my area, creating polygons that represent burnt areas. my problem is that the values are not accurate... for instance, arcgis ...
3
votes
1answer
312 views

How to calculate buffer surface that falls within another layer's borders

The image below shows what two selected layers. One contains a series of borders, and the other a series of buffers. I am trying to obtain the buffered surface within each of the borders in the ...
6
votes
2answers
7k 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?
4
votes
2answers
1k 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 ...
4
votes
2answers
779 views

Why does ST_Area(g.geom) + ST_Area(p.geom) - ST_Area(ST_Union(g.geom,p.geom)) produce negative result when using ST_Overlaps(g.geom, p.geom) = true?

I have two set of shape data. Let's say file gov.shp contains list of post codes and their boundaries. File post.shp contains list of government area name and their boundaries. I want to find out the ...
-1
votes
1answer
239 views

Finding the area of a polygon feature in a shapefile [closed]

Excuse the very simple question. How do i find the area of a selected polygon feature in a shapefile?
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vote
3answers
554 views

How to calculate forest area of a bitmap (jpeg) map?

I have a map of 1:50,000 scale map in .jpg format. Can i calculate the land area of forest,lakes etc from arcmap.Anybody can give me the step to do it? And I want to know what is the coordinate ...
2
votes
1answer
2k 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 ...
6
votes
2answers
354 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 ...
2
votes
3answers
299 views

How to calculate exact area of a loaded jpg map in to arcmap?

I calculated the polygon area through arcmap.but i'm not sure that the area is not actual,may be scale is not right. so how to calculate the exact area of a jpg image?
3
votes
1answer
3k views

Calculating area of an EPSG:4326 Polygon [duplicate]

Possible Duplicate: What is the most accurate coordinate system for calculating areas of polygons? In our Postgres/Postgis database we store polygons in a column defined as ...
1
vote
1answer
309 views

How can the scale be projected correctly in Quantum GIS when it is imported from google earth (KML) files?

While importing KML files from google Earth to Quantum GIS, the scale is not being projected properly and the area of a particular selected feature is not being calculated in the attribute table by ...
1
vote
1answer
2k views

Measuring on OpenLayers map

These days, I am trying to develop web map using openlayers. I copy source code from here Then I changed code to display my data.B ut it does not work, even map is also not showing. In chrome shows ...
1
vote
1answer
608 views

How to color markers based on polygon area?

I have a map with around 317 markers and each marker is the center point of a polygon. The polygonal area varies throughout, so I want to represent the markers in such a way that the polygon with the ...
3
votes
1answer
226 views

km2 or sqkm - which is more correct?

What is more correct, km2 or sqkm? I'd prefer to use km with a superscript 2, but it's not always possible to format text that way so I was just wondering if there is a convention that should be ...
1
vote
1answer
446 views

The units of getArea() on a multipolygon within a shapefile [closed]

I am using GeoTools to find area and intersections of shapefiles. GeoTools uses the JTS geometry library (Vivid Solutions) and that has functions to getArea() but unfortunately I am not able to ...
5
votes
2answers
1k 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 ...
2
votes
1answer
189 views

Converting 2D shapefile to Equal Area Projection?

I have thousands of shapefiles with coordinates in lat/long (-180 to +180 x, -90 to +90 y), that contain polygons of which I wish to calculate the area. I'm using the Python GEOS/OGR/GDAL API. If I ...
2
votes
1answer
507 views

Why does intersect not calculate polygon areas?

this is strange: I intersected 2 shape-files and the resulting shape does not contain the Shape_Area and Shape_Length of the intersected polygons. Instead the field Shape_Area contains the ...
4
votes
1answer
2k views

How to display Radius after Resizing a Feature in Openlayers

@captDragon has helped me with calling the coordinates of a polygon after I have resized or dragged the feature. Ineed the radius now, i have done a radius alert on my other map,Which works correctly, ...
0
votes
1answer
776 views

how do i calculate polygon area with arcobjects?

i'd like to develope an application with arcengine that can calculate area of a polygon . i wrote the below code to select a polygon in combobox for (int i = 0; i < pmapcontrol2.LayerCount; ...
0
votes
1answer
437 views

how to calculate polygon area in arcengine

i'm new to use Arcengine 9.3 . i would like to create an application to calculate the selected polygon in combobox such that the user click to a button and polygon area saved in dbf . how can i write ...
2
votes
1answer
494 views

SUM Area irregular polygons per grid cell

I have a shapefile of irregular polygons and a GRID (both as raster and polygon grid). How can I count the AREA SUM of irregular polygons per grid cell? Can use ArcGIS, QGIS or R. (Application: ...
14
votes
2answers
3k 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 ...
2
votes
1answer
2k views

ArcGIS10 - How do I dissolve two different buffers together so they are not overlapping?

I am trying to find out how many registered sex offenders live within 2,000 feet of a school/park in a specific county. The park buffer and school buffer are dissolved but not together. I am also ...
4
votes
2answers
1k 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 ...
4
votes
2answers
314 views

Total newbie. Creating map from aerial photo of golf course in QGIS

I have a aerial photo in tif with a tfw file of the golf course that I work at. I would like to create vector data of different features on the course such as greens fairways tees, etc. to calculate ...
2
votes
1answer
841 views

Area units for GEOS area property?

I'm working with GeoDjango and have a polygon in the WGS84 projection. I need to find its area in square meters. When I call polygon.area, I get some float out and I have no idea what the units of ...
6
votes
2answers
2k views

Openlayers geometry: how to convert area from degrees to square kilometres?

I get a multypolygon from my web service and want to calculate the area of that polygon. I was trying to use this piece of code: var poly = new OpenLayers.Geometry.MultiPolygon(poligon); var area = ...
5
votes
1answer
320 views

Geometry Calculation

Wanted to ask about accuracy of areas calculated by GIS compared to actual ones on ground. Because I have data of my country without areas for the districts within Uganda. Are the areas obtained using ...
4
votes
4answers
5k 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 ...
6
votes
1answer
96 views

Dividing the world space to geographic sub-space

I am trying to divide the world space to geographic sub-space from "general" to "specific" locations and without using latitude and longitude information. That is, I am trying to think about the world ...
3
votes
3answers
719 views

Overlay polygons on raster colour map to extract area values for each colour within each polygon

Does anyone know an answer to the following: I have a set of polygons created as the MCP of animal movements. I also have a habitat colour map raster, with 13 different habitat types as different ...
3
votes
3answers
12k 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 ...
5
votes
2answers
2k 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: ...
1
vote
4answers
4k views

Sum of areas in all each polygon layer?

I've got several layers/feature classes in an ArcMap 10 project. Thanks to everyone's help, I'm able to get the areas for the polygons contained within each layer. By opening the attribute tables ...
3
votes
2answers
6k 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 ...
6
votes
0answers
687 views

How to split polygons without ArcView? [closed]

I'm trying to split polygons into equal areas. While fishnet sort of works; the areas I'm trying to split don't touch; they're national parks. Fishnet spans the whole area, not just the polygons in ...
11
votes
5answers
5k 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?