Measure of quantity of a two-dimensional surface
11
votes
5answers
3k views
How can I measure area from geographic coordinates?
If I have polygons in geographic coordinates (WGS84), how do I measure the total area each takes on the surface of the earth, taking into account the curvature of the earth?
2
votes
2answers
176 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
3answers
225 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 ...
6
votes
1answer
355 views
How to calculate te area between contour lines on a DEM with Qgis 1.8?
Does anyone know how to calculate the area in km² for each altitudinal band (between 100 and 200, 200 and 300...) based on a DEM? I added the contour lines with a distance of 100 metres but could not ...
4
votes
2answers
322 views
How to calculate area of 1 x 1 degree cells in a raster
I have a simple array (not geo-referenced in any way) in Matlab (which is not a language I know a huge amount about...so I can export it to other languages if needed) which has the dimensions 180 x ...
2
votes
1answer
774 views
Convert area from square meters to degrees globally
I have a global raster file with 3600x1800 pixels. I don't have any information about the projection used.
The raster contains one band with a quantity with the unit "per square meter". How can I ...
3
votes
3answers
8k views
Calculate projected area of polygons with field calculator in ArcMap 10
I've got a polygon featurelayer in arcmap.
The coordinate system of the featurelayer's featureclass is web mercator.
The dataframe of the map uses an equal-area projected coordinate system.
I've ...
6
votes
3answers
372 views
How do I get the area of a WGS84 polygon in square meters?
The following gives me the area of the polygon in square degrees:
SELECT ST_Area(ST_GeomFromText('POLYGON((871325.790874952 6105405.3261047,871418.748307692 6105359.72944624,871346.22022442 ...
4
votes
2answers
2k views
How to calculate polygon areas and perimeters?
If I load a polygon layer and make a new column, how do I fill that column with the 1) area of each polygon and another column with 2) the length of the perimeter of each polygon?
3
votes
2answers
122 views
Determine density or cover from a raster layer that has been clipped by a polygon
I am a very new GIS user using ArcMap 10. I have a raster layer of tree canopy that I have clipped so that the layer is in a polygon that is a circle with a 2km radius.
I have done this for four ...
3
votes
2answers
4k views
Cannot get areas for polygon layers in ArcMap 10
For an ArcGIS project opened in ArcMap 10, we have added polygon layers representing different geographical features.
After all the polygons were created, we opened the attribute tables for those ...
2
votes
0answers
68 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
2answers
301 views
calculate area of vegetations in a raster file
How do I calculate area of several vegetation types in a raster (.img file type) image. They are color coded. Am using QGIS (1.8.0) and ERDAS 9.2.
4
votes
2answers
768 views
How to find the area of raster values within polygon zones?
I'm using ArcGIS 9.3 and I just can't seem to get this right - I've tried tabulate areas, zonal stats, converting to polygons, etc. I'm missing something somewhere.
I have a USGS impervious surface ...
3
votes
1answer
59 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 ...
3
votes
4answers
3k views
How to recalc WGS84 Shape_Area field to square miles in ArcGIS 10
What are the units of the Shape_Area field in a wgs84 feature class? Is it decimal degree squared?
I would like to convert that to something more meaningful like square miles without reprojecting the ...
2
votes
1answer
111 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 ...
