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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8
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2answers
148 views

More accurate way to calculate area of rasters

In my daily work, I am constantly asked to calculate areas of global raster datasets in geographic projection at 30 arc second resolution. These datasets are normally the result of a Combine operation ...
4
votes
1answer
79 views

Routing ensuring all areas are touched

I'm making a web application with leaflet and OSM. It's all going well, but now I need a little help. I'm searching for a good routing engine, that's capable of creating the most probably taken route ...
0
votes
1answer
40 views

Converting area of a polygon from steradians to square kilometers using D3.js?

How can I find the area of a polygon in square km using D3.js? I'm not even really sure whether to use d3.geo.path.area or d3.geo.area. Here is my code (JSFiddle): var d = { "type":"Feature", ...
3
votes
1answer
48 views

Thiessen Polygon Total Area Calculations Model Builder/Python Code

I am attempting to create a tool using Model Builder (and Python code) for calculating the average annual precipitation of a study area using the Thiessen Polygon Method. My model runs good other than ...
1
vote
1answer
38 views

Is product purchaser in distribution area?

I am going to be using PostGIS 2 to create a lookup service. Given a point (lat/lon), I need to either find if a product can be distributed there, or b) a list of products or distributors. I am ...
3
votes
0answers
64 views

Why do each of my buffer-polygons have different areas

I`m using Qgis 2.2 and 2.4 and loaded a wms-map using the coordinate system ERTS89 UTM 32N. I set 8 points (all in on shp-fileand in UTM 32N) on various locations on the map. After that i created a ...
0
votes
1answer
57 views

Is it possible to have auto-updating area fields?

I'm using QGIS 2.4.0 and I've noticed some problems with the derived area and the $area field. Firstly, I have a polygon which is a filled ring, inside another polygon. The derived area, and therefore ...
0
votes
0answers
60 views

Dividing a polygon into certain areas (open source solution preferred)

I have a polygon with an area of 50.000m². Now i want to devide this area in two polygons of different areas with a line layer. The left polygon should have an area of 30.000m² and the right polygon ...
0
votes
1answer
34 views

largest area polygon

I have a layer of polygon shapes, I know this could be a quite easy question to answer but I am a beginner and probably I am not using the right concept or terminology when looking at the desktop help ...
0
votes
1answer
44 views

How do I measure the area difference between polygons in different shp files?

I have couple if shp files with 1000 polygons scattered in them (around 1k in each file) , each shp file represents a time frame (3 months period) and I want to show the a report with a progress of ...
-1
votes
1answer
38 views

creating circle with radius in metres

I am using shapely and python. How should I go about creating a circle using shapely whose radius is in meters? If i use sampleCircle = Point(1,1).buffer(1) print sampleCircle.area This returns an ...
3
votes
0answers
29 views

What is the area that OGR extracts from the (geometry) shp files for polygons?

The ESRI July 1998 technical documentation for polygon shapefiles at page 10 makes no mention of either area measures or length measures (apart from byte/record-layout matters). Yet OGR enables me to ...
2
votes
2answers
79 views

Python Add-in- Message Box to display area of selected polygons

I am looking to create a Python AddIn which calculates the area of selected polygons. I would like to be able to select the features, click a button on the toolbar, and a Message box displays the sum ...
2
votes
1answer
58 views

Prior art on rhumb line and great ellipse areas?

I'm adding the computation of the area betweeen a rhumb line or a great ellipse and the equator to GeographicLib. My formulations are briefly given in here and here. These formulations are similar ...
2
votes
1answer
87 views

Calculating area of polygon inside region?

I am new to geographic information systems and i need to calculate the area of a a polygon ( a circle to be precise) that falls inside the boundaries of a region, say a state or a country. For ...
3
votes
1answer
81 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 ...
1
vote
2answers
153 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 ...
1
vote
1answer
36 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
votes
1answer
86 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: ...
1
vote
2answers
111 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 ...
0
votes
0answers
29 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
votes
1answer
143 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
votes
2answers
139 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
votes
3answers
71 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?
1
vote
1answer
87 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
votes
2answers
94 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
90 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
votes
1answer
80 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
vote
1answer
24 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
79 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
votes
2answers
121 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 ...
3
votes
3answers
58 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
vote
1answer
98 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
votes
1answer
99 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 ...
0
votes
1answer
61 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
votes
1answer
116 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
votes
1answer
51 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
votes
1answer
156 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 ...
0
votes
3answers
67 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
votes
1answer
125 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
votes
1answer
75 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 ...
0
votes
1answer
107 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 ...
1
vote
0answers
53 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 ...
1
vote
3answers
533 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.
0
votes
1answer
40 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.
0
votes
0answers
24 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 ...
1
vote
2answers
1k 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 ...
1
vote
2answers
166 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 ...
1
vote
0answers
66 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
votes
1answer
113 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 ...