Tagged Questions

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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1
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3answers
132 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
50 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
220 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
votes
0answers
25 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
54 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
77 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 ...
0
votes
0answers
106 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 ...
0
votes
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
342 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 ...
1
vote
1answer
65 views

Is there any way to add an area column to new shapefile created from raster with gdal's polygonize in the same step?

I've been going through a fairly lengthy process of polygonizing very intricate raster images, then creating a new layer with the extra area attribute, so that I can then remove the millions of tiny ...
2
votes
0answers
23 views

Why outside border of a service area is always not reasonable?

In ARCGIS 10.1 network analysis, why results of service area are different if number of break points is changed? For example, the grid is 300m*300m, I try to produce service area around a node. ...
0
votes
0answers
70 views

How to paint area below certain elevation, using no coding and Google Maps, Google Earth, Bing

How can I show the area below a certain elevation, using Google Maps, Google Earth, Bing Maps or similar end-user application, and no coding? Thanks in advance
0
votes
0answers
89 views

How do I optimize the speed and enable ArcGIS to create the Service Area around my locations?

The Problem: Every time I try to solve the service area around locations, ArcGIS crashes. It takes forever to load facilities and draw just a single polygon. How do I optimize the speed and enable ...
2
votes
3answers
466 views

Calculate Area proportional

I have two tables both of them having polygon geometry. Lets consider Table 1 has bigger polygons which overlap over the smaller polygons in table 2.Now I know how to find how many polygons from table ...
0
votes
1answer
98 views

Area of a Cross Section GRASS GIS 7

I have a task I would like to solve with GRASS GIS 7, if somehow possible. I want to create a cross section from a landslide - and would like to calculate the area of that cross section/profile. Any ...
2
votes
1answer
220 views

extend the size (area) of raster

My problem is that I would like to multiply two rasters using raster calculation tool. Both rasters have values 0 and 1, but the covered area of first raster is bigger (100 x 100 miles) then the area ...
1
vote
2answers
87 views

how create a specific sub-study area in ArcGIS 10.1 - difficulties with classification

My study area is quite large (sometimes spanning across a few grid squares) and when I am running a viewshed analysis or calculating slope or euclidean distance it calculates for the entire region. ...
3
votes
1answer
211 views

Can't compute area of shapefile in field calculator

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
47 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
68 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 ...
1
vote
1answer
129 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
289 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
50 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, ...
0
votes
0answers
79 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 ?
1
vote
2answers
96 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
votes
2answers
94 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
86 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
311 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
200 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
votes
1answer
190 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
110 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
146 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
571 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
339 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
167 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
206 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
vote
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 ...
4
votes
0answers
192 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
91 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
167 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
804 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
310 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
vote
0answers
63 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 ...
6
votes
4answers
3k 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
233 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
160 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
154 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 ...
1
vote
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
votes
1answer
69 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 ...