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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4
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1answer
617 views

Cannot compute area of shapefile in field calculator of QGIS?

This shapefile represents the counties of NM. I am trying to compute the area of each polygon (yes, I know there is an area field, but this is a simpler example of a problem I'm having which doesn't ...
2
votes
1answer
68 views

How to choose an area (of mxn metres) within a raster that have values above a certain range

I've got a raster of concentrations of iron on Mars and I want to be able to choose several areas of either m by n dimensions in metres, or just any area in m^2, that encapsulate regions that have ...
1
vote
1answer
105 views

How to restrict buffer extent within land area only?

I need to create buffer for a point feature, but the buffer area will be restricted within the land area only. For example consider the following: A buffer of say 500 km radius is to be generated ...
2
votes
1answer
428 views

Tabulate Area for large datasets

I have been struggling trying to use Tabulate Area in Arc 9.3 for a large raster dataset. I have one raster with 8 land uses and another vector layer with zones (which I converted to a raster with ...
3
votes
3answers
768 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 ...
0
votes
1answer
66 views

Newbie help — What do I need to calculate the 3D area of a terrain?

I have a terrain right on the side of a hill in Mexico. Initially I thought I could get the area from Google Earth, but after a few tests I found out that the area Google Earth calculates is flat, i.e....
0
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0answers
86 views

Query area without “AREA” field

In ArcGis 10.2 I'd like to show only polygons over 1m2, using something like a query. Can I do this without adding an AREA field and calculating/populating it in my table ?
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2answers
173 views

how to identify qgsvectorlayer area?

I need to identify the area from Qgis qgsvectorlayer anyone have an idea how to do that in python ?
0
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2answers
165 views

Count the area of rasterdata in specific shapefile polygons (residential density in different districts)

I'd like to count the exact area of three different residential classes (low, medium, high) by district of a shapefile which contains 225 districts. like: district 1 has: XXX sqm low, XXX sqm medium, ...
4
votes
1answer
110 views

Area calculation of an object without coordinates

I have a photo of an object with a scale and I want to calculate its area. I guess I have to create a polygon of the area to be calculated to use the 'field calculator'. But how do I tell the program ...
3
votes
0answers
688 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 ...
1
vote
2answers
458 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 !shape.area@...
2
votes
1answer
674 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
votes
2answers
197 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
vote
1answer
157 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
votes
0answers
1k 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
votes
2answers
775 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
315 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
440 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 ...
2
votes
0answers
92 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 ...
5
votes
1answer
486 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
votes
0answers
132 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
402 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
votes
0answers
2k 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
978 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. ...
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0answers
69 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 ...
9
votes
7answers
11k 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
2answers
667 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 ...
1
vote
4answers
201 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
388 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
29 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
61 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
votes
1answer
76 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
vote
2answers
420 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
562 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
846 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
votes
0answers
450 views

How can I calculate raster cell area for upslope contributing area

I am new to spatial analysis, and trying to follow this tutorial to generate a topographic wetness index for my area of interest: http://gracilis.carleton.ca/CUOSGwiki/index.php/...
0
votes
2answers
1k 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
426 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
2answers
920 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 ...
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 ...
3
votes
2answers
709 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
848 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 re-...
2
votes
1answer
226 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 ...
3
votes
2answers
8k 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
223 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 ...
3
votes
1answer
6k 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
793 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
132 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 ...
8
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 ...