combining map data of similar dimension to produce new maps using algebraic operations

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1answer
107 views

Map algebra from files in multiple directories

I'm a rookie in python programming. I want to do map algebra for multiple rasters but these rasters are in different folders. Here's the code ive created so far: #Importing modules import arcpy from ...
4
votes
0answers
110 views

Vector to raster, then map algebra

I have a table of polygons representing travel time isochrones on particular days. For each origin point, there are five isochrone geometries (stored in separate rows). For each origin point, I want ...
2
votes
0answers
68 views

Plotting Vector Arrows from U and V Component with ArcGIS for Desktop?

I have two raster layers representing the U and V components of a vector wind. I could generate the magnitude raster by applying Square root in Map Algebra in ArcGIS. I also generated a raster layer ...
2
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0answers
75 views

Arcpy script for summing pixel values in loop can't handle large number of rasters

I want to sum the pixel values of large numbers of rasters of different extents (ArcMap v10.2). 16GB RAM. I have the following code (with help from this site) which solves the different extent ...
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vote
0answers
85 views

How to compute the ls factor equation for USLE model in qgis grass r.mapcalc

To compute the LS factor for the USLE model, the following equation easily works in ArcGIS. How can I perform the same in QGIS under GRASS r.mapcalc? LSfator = Power (("flowaccNW") * ...
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0answers
151 views

Map Algebra in VB.NET Add-In Tool

I'm trying to run a map algebra expression in a vb.net add-in, and can't seem to get it to work. It's a roving window that interpolates noData areas in a DEM. The expression works in the Python ...
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0answers
27 views

ArcGIS Raster Calculator wont work in main model

I've created a Submodel in ArcGIS, which stretches my rasterdata to new values. The strange thing is, that the model works, if I run it itself - as soon as i implement it in the main model, I get ...
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0answers
33 views

multiply a rang of values in a floating raster to a constant

I have a floating raster layer. I want to multiply a rang of its values to a constant. So, I used the "Con" tool in map algebra with the following script. Con(("Extract_rast1" >= 0) & ...
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0answers
66 views

How to speed up raster/map algebra in PostGIS?

I am testing map algebra with PostGIS (2.1 with PostgreSQL 9.3) on two images, and found it to be rather slow. For example, dividing two images of 7200 * 3600 pixels took 110 ~ 120s on a desktop with ...