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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3
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0answers
217 views

Extract values from raster based on weighted average area using polygon grid

EDIT: I am using Armap 10 sp 5 I have found similar questions but they were either unanswered or somewhat different to what I am asking. I have a raster with cell values 1-5 and a polygon shape file ...
0
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0answers
25 views

Get records that are in specific area - defined by array of points

I have a Rails application. I have records that contain long/lat field. I want to be able query the database with array of long/lat points (together they form closed shape area), and get all the ...
1
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2answers
155 views

Using a different projection to calculate areas using the Field Calculator

I have a dataset that is in a WGS84_UTM projected coordinate system, can I force the Field Calculator to use another coordinate system when I use it to calculate areas using pythons ...
2
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1answer
117 views

Unable to change the layer unit in QGIS

I have been working with QGIS for 2 weeks and I got the hang of it now. The problem now is I cannot calculate the area of a created polygon. Because the layer unit is not changing to meters. When ...
0
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2answers
89 views

Finding cumulative area in ArcGIS for selected polygons

I have 50 polygons of 5 different classes viz. A,B,C,D,E. and a field in the attribute table for area of each polygons. I want to add a field which give the cumulative area of the polygons of a ...
1
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1answer
143 views

Visualise data belonging to an area

I am looking for a way in QGIS (1.8.0) to visualise data, which is related to an area (polygon on a shape file). There are no x-y-coordinates with the data, just the info of the belonging area, means ...
2
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0answers
450 views

Projecting a Raster from WGS84 to planar Equal Area to Calculate Area: How to Select the Cell Size?

I have a broad question on how to calculate the 'correct' cell size for a raster when analyzing an area not at the equator. My goal is to project a land cover raster provided in GCS WGS84 to an equal ...
2
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2answers
257 views

Is the derived area/length/xy values of a polygon/polyline layer in QGIS usable?

I have a raster that is projected to a state plane CRS and I am adding polygon/polyline shapefiles that are projected to WGS84. On the fly transformation is set to reproject to my raster CRS. When I ...
1
vote
1answer
136 views

Calculating area of MultiPolygons within 250m buffer of points

I am using using PostgreSQL 9.2 and PostGIS 2.0. I have two tables: 1) a geocoded table of home addresses (address_list) and 2) a table containing data on tree density in the same geographical area. I ...
4
votes
1answer
168 views

How can I accurately measure area of polygons using field calculator in qgis?

I have several polygon shapefiles, both set to WGS84 CRS. I have been using the google basemap with the Openlayers plugin, using the mercator CRS. On the fly CRS transformation is enabled. Should ...
1
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0answers
53 views

Determining homogenous blocks of individual tree species in a woodland, and creating a new shapefile without blocks/polygons of < minimum area?

I'm working on a project attempting to identify suitable woodland habitat for red squirrel translocation wherein conservation efforts could be focused. Below is a small section of the map showing ...
3
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0answers
141 views

Tabulate Area ArcGIS

I am trying to work out the relationship between the 'processing cell size' and the result from Tabulate Areas. If one uses the same as the raster cell size, and this is the same for both rasters, the ...
3
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0answers
86 views

Reshaping polygons while preserving area

I'm looking to manually skew the shapes of areal polygons, but need to ensure their areas are not altered. Is anyone aware of any GIS tools or programming workflows that exist for manually reshaping ...
2
votes
1answer
129 views

QGIS vs. SVG export w area names

Salve a tutti, esiste la possibilità di esportare un file SVG (a partire dallo shapefile) che conservi però i nomi delle aree? In sostanza ogni tracciato chiuso dovrebbe avere il nome originale ...
0
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0answers
533 views

How to split polygons based on other polygons?

In ArcGIS, I have a layer of polygons (created from the Service Area function) and want to split each one of those based on another polygon layer (the boroughs of London). The purpose is that I want ...
3
votes
2answers
172 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. ...
1
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0answers
52 views

How to measure area of polygons generated from gps data in qgis? [duplicate]

Somebody classified my question as a duplicate. But applying the answer doesn't work for me. Here is what I did: - I made sure that my layer is in a projected coordinate system (UTM30N, WGS84) - I ...
5
votes
4answers
2k views

How to remove only donut holes from polygons 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. The drawback of this strategy is ...
1
vote
1answer
191 views

How to compute area for polygons in an EPSG:4326 shapefile?

I have a shapefile covering the whole globe, in EPSG:4326 (geodetic WGS84). I would need to compute the polygons areas in a metric such as km2. How can I do that in QGIS or with gdal/ogr and having a ...
0
votes
4answers
149 views

How can I calculate different polygons by different attributes?

I'm doing my master thesis and want to calculate different polygons (in QGIS 1.8 for Mac) in four different columns which I defined by different attributes. i.e. some of the attributes in the first ...
0
votes
1answer
123 views

How to import a simulation from ParaView to ArcMap?

I made a simulation and reworked the output with ParaView. I simulated an avalanche on a DEM and what I want to do is to compare the area of the simulated avalanche with that of the real avalanche. To ...
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0answers
23 views

Creating a buffer based on area (i.e. sqm) instead of distance [duplicate]

Is there a way in ArcGIS 10.1 or QGIS (or any add-on) to create buffer based on an area (i.e. sqm) rather than using buffer distance? I'd like to create a buffer of let's say 5% of the area within the ...
1
vote
2answers
49 views

Does OSM2po handle squares and places?

OSM2po is converting data from OSM to postgresql. But how is it handled with places or squares? Not every places, square has pedestrian way routes on it. But for routing I need nodes and pedestrians ...
0
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1answer
67 views

Raster image outside Grass screen, How to get it inside from start?

HI ALL: I'm new in Grass and need some help! I have created a LOCATION based on the coordinate system in which I want my data to be projected. So far I'm being able to Import & display the raster ...
1
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2answers
202 views

How to re-calculate area, perim, p2a,width and length in QGIS?

I cut a part out of one feature and added it to another feature in a polygon shapefile. My problem now is that both features has the same values in the area-, perim-, p2a-, width- and length-columns? ...
0
votes
1answer
189 views

How to calculate the area of the convex hull of a points layer

I have a shapefile in QGIS that I have created by importing a CSV of points, using Points2One to convert to a shapefile and then importing the shape. I am now trying to calculate the are of the shape ...
2
votes
2answers
399 views

Why is QGIS Field calculator button greyed out?

I'm using QGIS to attempt to calculate the area enclosed by a set of points that I have capture used a GPS device. I have imported the coordinates from a CSV but when trying to open the field ...
0
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0answers
161 views

How can I calculate raster cell area for upslope contributing area

I am new to spatial analysis, and urgently trying to follow this tutorial to generate a topographic wetness index for my area of interest: ...
0
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2answers
309 views

How to scale/reduce my polygon without changing the central lat & long?

I am writing a VBA code to resize my polygon, I get a input as vector points(Shape file). The code below resizes it as according to my scale factor but my central latitude and longitude are also ...
1
vote
1answer
207 views

How does QGIS calculate the area of a polygon?

I am working on a project that requires the calculation of the area of a polygon by two different methods. I need to know what algorithm QGIS uses to calculate the area of a polygon. I know ESRI ...
3
votes
1answer
346 views

How calculate areas between certain contour lines in qgis?

Sorry for asking a question which I found in similar ways already here, but I am trying this for days and just got no result: How do I calculate the area between certain contour lines (e.g. 0-800, ...
2
votes
1answer
709 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 ...
3
votes
2answers
285 views

How to calculate the shared area between a raster and a shape file in ArcGIS 10?

I have a raster file with 5 classifications developed from habitat modelling algorithms. I'd like to know how much of 2 classes of the raster is covered by the network of protected areas (Shape file). ...
3
votes
1answer
384 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 ...
2
votes
1answer
164 views

Calculating area [closed]

I have a polygon layer. I toggled to edit mode. I added a new column, while number (integer) and called it "area". I then use the field calculator - geometry - $area to populate the polygon area for ...
2
votes
1answer
2k views

What are the units of the calculated area from a raster in decimal degree

I'm trying to calculate area for a raster file which contains 2 layers (0 for unsuitable habitat and 1 for suitable). It's been calculated successfully but I don't know what is the unit of the ...
3
votes
1answer
133 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
1answer
2k views

How to combine (join?) two overlapping polygons to determine combined area they cover?

How do I combine (join?) two overlapping polygons to determine the combined area they cover in ArcGIS 10? I am sure the Geoprocessing tools can do it, but just how eludes me.
2
votes
2answers
387 views

How to calculate area in sq km of an ellipsoid shapefile

In QGIS, I often find myself setting up projects with an ellipsoid coordinate system (e.g. WGS84) so that the resulting maps have lat lon scales, etc. Often in these projects I also need to do some ...
2
votes
0answers
98 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 ...
6
votes
1answer
3k 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 ...
0
votes
2answers
251 views

Calculating area gets a different result

I've calculated the area of polygons with QGIS by using ctr-i - geometry - $area. I've set it on real. The results seem fine, but I've noticed they differ from the area given when I use the ...
2
votes
1answer
352 views

How to measure the area of polygons within a fishnet

I am currently trying to measure the area of polygons within each square of a fishnet. The aim of what I am doing is to work out the proportion of different agri-environment schemes by 1km squares. ...
1
vote
1answer
60 views

QGIS 1.8.0 Mac where is measure window or measure area symbol?

Just trying to measure the area of a selected polygon (a few km2) but can't find out where the measure symbol is (mentioned in some posts here) or how to get the measure window shown in the manual. ...
3
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2answers
704 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.
3
votes
1answer
1k 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 ...
4
votes
1answer
278 views

The number of digit of decimal point when you calculate area of polygon in QGIS1.8.0

I would like to change the number of digit of decimal point when I calculate area. For example Now: 32.456677 Ideal: 32.46 I try to adjust "output field width" and "Precision" These don't work well. ...
3
votes
3answers
722 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 ...
5
votes
3answers
362 views

Polygonize vegetation area from Landsat7 RGB using QGis / Bilko?

I'm trying to extract the areas with vegetation as a polygon-shape from a landsat7-image, 30m resolution, RGB, using QGis 1.8 or Bilko or (hopefully in the near future) ArcGIS. The area is in Northern ...
0
votes
1answer
400 views

Which area measurement to trust? - The same polygon in GoogleEarth v. ArcGIS [duplicate]

Possible Duplicate: What is the most accurate coordinate system for calculating areas of polygons? I'm currently involved in comparing the "official metropolitan" areas of several cities ...