Linked Questions
25 questions linked to/from Coordinate system for accurately calculating areas of polygons that cross UTM Zones?
12
votes
1
answer
12k
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 ...
- 295
0
votes
1
answer
4k
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 ...
- 61
0
votes
1
answer
211
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 ...
- 623
1
vote
0
answers
284
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)?
- 11
4
votes
1
answer
195
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, ...
- 989
1
vote
0
answers
98
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 ...
- 2,217
3
votes
0
answers
68
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 ...
- 361
13
votes
2
answers
7k
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, ...
- 3,421
8
votes
1
answer
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
2
answers
20k
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 ...
- 305
11
votes
2
answers
706
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 ...
- 327
4
votes
3
answers
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 ...
- 3,251
4
votes
2
answers
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 ...
- 1,445
1
vote
0
answers
3k
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 ...
- 161
3
votes
1
answer
951
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 ...
- 3,251
1
vote
2
answers
1k
views
How to calculate the area in kernel density?
I have estimated and reclassify my kernel densities and I would to calculate the area of each value. How could I do it?
My Projected Coordinate System is WGS84 World Mercator. My pixel size is 10000 ...
2
votes
1
answer
732
views
Changing projection for field calculator
I've just succeeded in getting the area of a polygon using field calculator. The polygon was drawn on a Google hybrid aerial photo. There are no units given in the calculation and I assume the area ...
3
votes
2
answers
698
views
How to calculate area in sq m - troubleshooting projection issues in a global dataset in QGIS
I am using QGIS version 2.12.3.
I have 3 polygon shapefiles: A, B and the intersect of A and B, which we can call C.
All I want is to add a field to the attributes table of each shapefile giving ...
2
votes
2
answers
1k
views
How does the projection of a dataset affect the results of spatial analysis?
I am planning on conducting a multi-criteria-analysis with a number of different source datasets. A number of the datasets are found in different coordinate systems and projections. Do I need to ...
- 215
1
vote
1
answer
382
views
Getting geodetic area from rgeos::gArea? [closed]
I need to get an area of different polygons at continental scale (like third of Africa etc.). Usual functions like rgeos::gArea work only in the projection units.
Is there any function which works ...
- 1,191
2
votes
1
answer
375
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 ...
5
votes
0
answers
372
views
Intersection and area calculations in geographic vs. projected coordinates
I think one should do intersection calculations when layers are in the same coordinate system, and one should do area calculations in the appropriate projected coordinate system.
The order matters, ...
- 71
2
votes
0
answers
463
views
How to choose a projection for area measurement on building to continental scales?
I have many geographical objects described as polylines, polygons, multipolygons. All objects are in WGS84. Object could be: a building, stadium, park, street, highway, city, state, even country and ...
- 327
1
vote
1
answer
143
views
Choosing projection for calculating 2D 3D area in New Zealand?
I'm trying to use Surface Volume tool in ArcMap to calculate 2D and 3D area of a catchment.
What would be the best projection to use and how do i check the maximum error of the estimation?
- 33
0
votes
1
answer
50
views
calculating ratio of areas on a sphere
I have 2 shapefiles and after identifying their intersections I'd like to know the ratio of intersecting areas, e.g.
a given shape S in file1 intersects with shapes (x1,...,xn) in file2 with ?...
- 179