# Questions tagged [map-algebra]

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

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### 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") * resolution/22.1,...
71 views

### Map Algebra loop only creating one raster

I'm trying to transform a bunch of rasters in arcpy according to specific functions to create suitability rasters. This portion of the code is supposed to find all the rasters with interpolated ...
406 views

### Calculating Aerosol optical thickness from Landsat 7

EDIT I have added question down I am reading one paper and I found method to retrive AOT from landsat 7 image This should be simplifield equation, because they assumed observation zenit as 0. Than ...
378 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 ...
41 views

### Using minus in water drainage model

I'm doing a lab and I'm trying to understand exactly why I'm using the tool "minus". I have a raster which I'm calling "heights". I also have two rasters with water surfaces and watercourse. I have ...
83 views

### Iterate a multistep Map Algebra

I am trying to write my first ArcPy script to iterate a Band Math process with requires a few steps. The uniterated, working script for a single group of bands in one Landsat scene is: #import ...
398 views

### ArcGIS Raster Calculator Error 000539

I am getting the error-000539: Error running expression: rcexec(). I've seen that other people have this same issue but I am not sure how to fix mine. I just want to average the values of 10 rasters, ...
82 views

### Writing Raster Calculator Map Algebra expression?

I have the following map algebra expression to be used in Raster Calculator. The "Output raster" should satisfy the following conditions: If (IsUseAWSSites == True): if (InputRaster exists): ...
141 views

### How to correctly input complex multiband functions in Raster Calculator?

I'm trying to compute a MTVI2 (Modified Triangular Vegetation Index - Improved) and EVI (Enhanced Vegetation Index) from Landsat 8 imagery. My formulas are as follow (I'm using ModelBuilder): MTVI2= ...
201 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 window,...
45 views

### Using tool “minus” in height model?

I'm doing a lab and I'm trying to understand exactly why I'm using the tool "minus". I have a raster which I'm calling "heights". I also have two rasters with water surfaces and watercourse. I have ...
18 views

### Buggy intermediate datasets in map algebra

I created a for loop to perform a (simplified here) series of operations over tiles from a larger dataset. My initial code looked like this: ext_template = bingmean_odd totalextent = arcpy.Describe(...