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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44 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 ...
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2answers
128 views

Calculate area inside polygons based on slope

I have some DEMs and have computed the slope in degrees for each one. I have also classified the slope raster into the following 5 classes: 0-3, 3-15, 15-35, 35-50, >50. What I want to do is to ...
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1answer
32 views

Looking for a complete list of cities by state, with area code

Our company is working on moving our sales assignments from area codes to ZIP codes, and we need some kind of dataset to help move existing assignments to the new system. Does anyone here know where ...
3
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1answer
64 views

Trouble calculating areas in QGIS using field calculator

I am testing various projections to calculate areas using ICES statistical shapefiles and the QGIS field calculator. I am using ICES areas downloadable from the following link: ...
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2answers
76 views

How to validate OpenLayers area calculation using PostGIS?

I am working on a GIS API that work on top of OpenLayers. I have a feature that calculates the area of a drawn polygon. I have tested it on the browser and the areas I got, appear to be correct. For ...
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23 views

Pros and Cons of a latitude adjustment grid vs other methods of area calculations

When working with high resolution global raster data in WGS 1984 I often need to calculate areas. Now the traditional way for me to achieve this has been to reproject the data to an equal area ...
2
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1answer
49 views

Calculating geometry area in ArcGIS for 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: ...
2
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2answers
131 views

How to calculate area of shapefile with a merged layer

so i have 'save as''d the new project and layer with my new Custom CRS project string being '+proj=laea +lat_0=70 +lon_0=0 +x_0=0 +y_0=0 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs'. ...
2
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3answers
49 views

How to figure out the unit of measurement from table fields?

I have a couple of fields with predefined values. In particular I have an 'area' field that I need to figure out its unit of measurement (e.g. km, miles, acres). What's the easiest way to do this?
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1answer
51 views

StArea() in sqlserver is in which unit?

I have a problem with saving STArea in sqlserver. Here is a query where I get the area of a polygon: select Geometry::STGeomFromText('POLYGON ((51.3386535086000000 31.7951253522000000, ...
4
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2answers
84 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. ...
3
votes
2answers
77 views

Create a buffer with a pre-defined area?

I have a road (line) system and need to create a polygon from it to show the right-of-way area. The right-of-way area is calculated in the field from taking measurements from the road centreline. From ...
2
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1answer
47 views

JTS “points must form a closed linestring”

I'm trying to create a polygon and calculate it's area using final GeometryFactory gf = new GeometryFactory(); final ArrayList<Coordinate> points = new ArrayList<Coordinate>(); ...
1
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1answer
21 views

Area of an EPSG 27700 polygon

I am working with EPSG 27700 polygon data in PHP. All the polygons are in the UK. The polygons do not have holes inside them. I'm hoping to be able to calculate the area of these polygons. For this I ...
2
votes
1answer
66 views

Problem measuring area with gps coordinates

I am trying to measure area from gps coordinates but fail to get the correct result (7200 square meters). I used the formula from this post but I get way too high number as result (should be in square ...
3
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2answers
96 views

Remove Holes Existing Within a Single Polygon for a specific area in Qgis

I have a shapefile that consists of a single polygon. I have gaps within the polygon that needs to be eliminated, but only the ones that are less than 200m2. I tried different ways but none of them ...
2
votes
2answers
45 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 ...
1
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1answer
58 views

How can I measure area in square kilometres from lat / lon gps coordinates?

I have code from openlayers that I cannot quite handle because I am so new for these kind of codes. My main goal is to measure area from n amount of lat/lon gps coordinates and convert the result into ...
2
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1answer
83 views

Defining projection, reprojecting, and wrong area values [duplicate]

Apologies for duplication--this was mentioned in a previous post, but was suggested that this specific problem should be posted separately. My data: http://water.usgs.gov/GIS/dsdl/aquifrp025.tar.gz ...
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1answer
54 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 ...
0
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1answer
88 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 ...
0
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1answer
36 views

Calculating Area of Raster Classes

I have a raster in a GRID format that was created by Image Classification. The GRID is projected in StatePlane meters, but I would like the area in square feet. I'm assuming I will need to use the ...
3
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1answer
120 views

Calculate population coverage?

I am relatively new to QGIS and hope I explain this right. I am looking at the percentage of an population that has geographical access to healthcare. Therefore I have one shapefile with village ...
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3answers
60 views

Same size polygons giving different overall areas

I am currently working with multiple shape files that I have clipped to the exact same extent, but when I calculate area (acres) within each polygon. I am getting different results between the ...
0
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1answer
88 views

Determining if a Geodetic location is inside a polygon made up of Geodetic vertices

Suppose we have a polygon with Geotic vertices (Points A through E). Is there an algorithm that I can use that could determine If F is inside of it? In addition, what is the most efficient way to ...
0
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1answer
62 views

Calculate tree cover over certain area from raster data

Last year Hansen et al. published Global Forest Change map as set of raster data available in TIFF format. Basically those are 30-meters resolution satellite images with pixel values ranging from 0 ...
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1answer
71 views

Difference in vector / raster area measurements

I'm comparing raster and vector distance zones. So I created a line, calculated the Euclidean distance, and reclassified the raster to two zones: from 0-10m and 10-20m. To compare it with vector ...
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43 views

How to calculate the area of overlapping buffers within a single layer

I am very new to GIS, so don't know if this is EXTREMELY easy or impossible. I have GPS coordinates for stores (about 15000) for which I have created a buffer zone around each store location ...
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2answers
274 views

Setting default units for Shape_Area to be Acres using ArcGIS Desktop 10.0

When I create a new feature layer polygon, how do I set the default in Shape_Area to read out in Acres? I am using ArcGIS Desktop 10.0.
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1answer
39 views

How to select a specific area (in a polygon form) determined by some value range in a raster band?

For example, I want create a vector layer with polygons that represents all areas where the elevation is between 500 and 600. Someone has any idea to help me? I'm using PyQgis 2.2.
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23 views

How to calculate area of lat/lon rectangle? [duplicate]

(Strange that this Q seems to be unanswered...) Given a rectangle like this, say (from Java, but that should be immaterial): double minlat; double maxlat; double minlon; double maxlon; How to ...
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2answers
831 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 ...
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2answers
118 views

ArcGIS 10.1 calculating area out of Aspects

I have used the aspect tool to visualize the 8(+ Flat) slopes of the different directions, now I would like to get the numbers of the areas for each different direction (+Flat). Anybody knows how that ...
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0answers
61 views

Problem with service area gap with Network Analyst

I am working on running Network Analyst to create a Service Area from a single location to all around it. Esri's network dataset was missing a couple crucial street lines, and so I uploading their ...
0
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1answer
91 views

QGIS: graphical-modeler to calculate area of polygons

I'm trying to calculate the area of polygons using the field-calculator in QGIS (2.0.1). If I do this manualy it works fine, but if I do this using the graphical-modeler I get NULL as area for every ...
1
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1answer
64 views

How to analyse point data as covariate for areal data

I have two data sets: a) a set of polygons with areal data variables. b) point measures of various co-variates of interest (note I do not necessarily have a point for each polygon) How do I ...
0
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2answers
51 views

How to remove small areas without reducing borders

I'm having a problem where I am overlaying two maps to create a new kind of map with the data conjoined. In general this is good, but I need to remove the smaller areas from it. For the interior ...
0
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0answers
61 views

How to calculate the area of an ellipse on the earth's surface using Python?

I have a dataset consisting of GPS coordinates. I use a clustering algorithm to generate a two dimensional Gaussian for me. The Gaussian takes the shape of an ellipse if visualized on the map. ...
4
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28 views

Projecting polygon when calculating its area? [duplicate]

I have a broad range of polygons (in vector format and in SpatialPolygonsDataFrame class), some going east-west, others going south-north, while even others span polar regions or very large ranges as ...
2
votes
1answer
132 views

Compute the area of a given polygon (in vector format) lying between specified lines of latitude

I have species distributions (in vector format) and I would like to calculate how much of the area for a given species distribution is within certain lines of latitude, such as temperate and tropic ...
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31 views

Finding a common area by a set of ID variables?

I am trying to find a way to find a way to get matches of areas based on multiple sets of ID variables. I am using state-county and state-puma as an example below, but I am wishing to do this for more ...
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3answers
109 views

How do I calculate the new shapefile areas after clipping?

I'm working with the WWF ecoregions, which use the GCS_WGS_1984 geographic coordinate system. I have clipped the ecoregions with a species range (consisting of two polygons), but the new attribute ...
0
votes
1answer
44 views

Getting wrong value for area of geometry using Spatialite?

I am trying to implement a measuring tool on apple maps for IPAD. As a part of that i collect all the touch points on the map into an array and constructing a geometry object from that and then ...
5
votes
2answers
213 views

How to calculate the area between two line shapes?

I'm a newbie using QGIS (2.0). I'm trying to calculate the sidewalk area of a city. For that I have some shapes, extracted from Mricostation, with the topology (facades, fords, fences, etc.), but ...
0
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0answers
24 views

Show the paths but not roadsides and driveways in the line layer

I want to display paths in the woods but the paths are all in One (line) layer that contains all roadsides, pavements, drivvays, but also paths, tractor road and other relevant roads in, and up to the ...
2
votes
1answer
50 views

Equal (ish) areas Map Projection at the Tropics

What map projection (non-interrupted) preserves areas well for the entire tropical region? I am thinking of using a Cylindrical Equal Area or a sphere based version of a Cylindrical Equal Area or ...
2
votes
3answers
75 views

Relative areas projection independent?

I need to calculate how much (in percent) each of thousands of spatial polygons shrink after some events. I use R and the very useful sp-library. Example: Projection: "+proj=longlat +datum=WGS84 ...
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0answers
99 views

changing unit of area from unknown unit to square meters

I am using Qgis 1.8 and I have this polygon.Now I wanted to know the area of this polygon and i have used field calculator and it shows my area as 651692439.under general tab crs is : EPSG:4326 - WGS ...
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2answers
74 views

Show only some buildings

How do I show only some buildings? I only need to show 3 cabins in the forrest, but not every house in the whole village around, and the city close by. Maybe some of the symbol buildings in the city ...
6
votes
3answers
308 views

How can I obtain the same area values provided by the Census for TIGER boundaries using PostGIS functions?

In PostGIS, how can I compute the area of Census Boundaries and obtain the same results as are provided by the Census? For example, most Census Boundaries include attributes for Land Area and Water ...