Linked Questions

12
votes
1answer
11k views

Calculating area of an EPSG:4326 Polygon [duplicate]

Possible Duplicate: What is the most accurate coordinate system for calculating areas of polygons? In our Postgres/Postgis database we store polygons in a column defined as lonlat/EPSG:4326, as ...
0
votes
1answer
3k 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 against ...
1
vote
0answers
258 views

how to calculate area if it is falling in two utm zones [duplicate]

I am using ArcGIS 10.1. How do I calculate an accurate area measure for a polygon, where portions of it are falling in two zones, i.e. UTM ZONE 44 & 45 (India)?
4
votes
1answer
180 views

Why does not equal length of line in DIRECTION/LENGTH with length of line in MEASURING in OpenLayers 2.13? [duplicate]

My map projection is: "EPSG:900913", display projection is "EPSG:4326" and units is "m", however does not equal the length in Direction/length with the length is calculated in measuring in OpenLayers, ...
0
votes
1answer
136 views

What is most accurate Spatial reference system for calculate Area entire world [duplicate]

I want to know what Spatial reference system is most accurate to calculate area? I want to use it for entire world (-180,+180,-90,+90 area in WGS84 system) I have every thing ok I only need to ...
1
vote
0answers
93 views

What is the right projection for area calculation in Kenya? [duplicate]

I want to calculate the area of counties (1st admin level) in Kenya in ArcGIS. What is the right projection for that? I know I should use an equal area projection, but when I use them (I tried six ...
3
votes
0answers
66 views

Projecting polygon when calculating its area using R? [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 ...
13
votes
2answers
6k views

ArcGIS Length and Area Calculation Scenarios [closed]

Trying to get a handle on how length and area are calculated in different scenarios in ArcGIS. I don't know why I can't find a answer on the feature class fields, but I can't find a precise answer, ...
8
votes
1answer
8k views

How to measure areas of features in OpenLayers plugin background maps correctly?

I can't figure out how to make areal calculations (eg. in km2). I have tried the 'field calculator', I have tried the 'measure area' function on the "attributes" toolbar, and i have tried fTools in ...
4
votes
2answers
19k 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 ...
11
votes
2answers
582 views

Why do I get correct area and intersect area when use wrong projection?

I need to calculate areas and intersection areas for polygons (some real geographical objects like lake, city, country, e.t.c.). Polygons located in California, New Zealand, Russia.Anadyr, Sweden All ...
4
votes
3answers
1k views

Which equal-area projection to use for UK?

I have a bunch of UK polygons that are saved in my PostGIS database as WGS84 projection. I would like to calculate the area of these polygons using st_area. According to this answer I can save these ...
3
votes
2answers
3k views

Polygon area calculation in Ruby (on Rails, rgeo, PostGIS and GEOS) in sqare meters

In a Ruby-on-Rails application, I need the area in square meters (or any other surface measure, be it ares, hectares, square kilometers, but not in pseudo surface measure like square degrees) of a ...
1
vote
0answers
2k views

Why Haversine formula and Web Mercator give different length between two latlng points?

I am calculating the distance between two points given by latlng. However, Google Maps (i.e., web mercator projection) gives me a longer distance than Haversine formula. Which is the most accurate ...
3
votes
1answer
615 views

PostGIS: calculate area of intersection of EPSG:27700 polygons?

I have two tables in Postgres, both of type geometry(MultiPolygon,27700) and I would like to find any that intersect with an area of more than 100 square metres. I know how to get any that intersect ...

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