# Tagged Questions

A tool in some GIS software programs for performing algebraic operations on rasters.

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### Combining information from multiple rasters into aggregate raster and populating fields accordingly

I am stuck on how to best combine the information from multiple rasters into one raster. Specifically, I am working with a time series of raster files, whereby each raster corresponds to a different ...
40 views

### Compare euclidean distance with network distance

I have a raster file with euclidean distance. It contains information about how long it takes for a chopper to arrive to certain destinations. I then have a polygon made from a service area with ...
64 views

### Calculating Geometric Mean in Raster calculator

I am calculating Geometric Mean for land degradation mapping. I am applying following formula in ArcGIS 10.2- ("GW.img" * "LULC.img" * "Rain.img" * "Temp.img" * "Wind.img" * "NDVI.img" * "Livestock....
15 views

### How it can be made a spherical cap surface with qgis raster calculator

I would like to make a test in QGIS raster calculation: I'd like to make in a flat raster surface (0m as elevation) a kind of hill or dome with the spherical cap geometry formula. P is the point ...
22 views

### Why would having a reference string “boh@10” cause a crash?

When using the raster calculator in a pyqgis script, I have several layers to process. When it gets to "boh@10", the processCalculation() call crashes. I don't see anything in the code that requires ...
102 views

### Sediment transport index STI

To calculate the STI one applies the following formula in the raster calculator: Power(“FlowAccumulationArea_Raster”/22.13,0.6) * Power(Sin(“Slope_Raster”/0.0896),1.3) Now I have a problem which I ...
68 views

### Raster Calculator and Land Change with multiple classifications

I am looking at land cover data that is separated into three classes: upland, wetland, and open water. I have the data for varying years. I am interested in seeing how the land has changed over the ...
31 views

### Do rasters have to be of same extent for the QGIS Raster Calculator?

I am trying to use the Raster Calculator but, I get a raster with Nan values. My rasters are in the same projection system but, one of them, it is a classified landsat map which covers only some part ...
65 views

### Con statement in raster calculator Arc GIS 10.3

I have four rasters (A, B, C, D) based on which my classification works. The con statement I have been using is posted below. My problem is when A_01 is 2. Area when A=2, if value of B is less than ...
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### How to change value in raster layer?

I have created future temperature raster (tiff format) in ArcGIS. However I want all pixel's value to be multiply with 10 (constant value). I tried to use con tool and raster calculator in spatial ...
65 views

### Summing pixel values from several raster layers with partial overlap in QGIS?

I have several presence maps (rasters values 1 and 0) from different species. They are all from South America, but they do not have the same extend (i.e., different sizes). So, I am trying to ...
31 views

### Raster conditional tool unexpected results. What's wrong?

I have a DEM raster (High: 53441, Low: -3444, unit: cms) with negative values, and I want to make all values 100 or less to be 100. I've tried Raster Calculator, and also python. I've got the same ...
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### Conditional statement in ArcGIS Raster Calculator?

I am new to Arcmap... I want to make a conditional statement in Raster calculator that checks if the pixel does not contain water or forest value ,, assign them snow as 1 and vice versa... Like the ...
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### Reclass a raster based off a percentage of the COUNT values using Con

I have a raster with a VALUE field and a COUNT field. I've sorted (descending) the VALUE field. Now I want to run a Con statement or a reclass to create a new raster based off the top 20% of the SUM ...
201 views

### Markov chains, cellular automata, and raster algebra

I need to build a probabilistic cellular automaton for simulating land-use changes and am wondering how to implement this in a GIS. I understand that Markov chains are a way of doing this, and IDRISI ...
60 views

### How to replace raster values in one Raster with another [duplicate]

I have two raster files in ArcGIS 10.1, raster 1 and raster 2 all with values and similar spatial resolutions, and overlay in some areas. I want to replace values in raster 1 with those in raster 2 ...
212 views

### Adding all Binary Rasters in a Directory Using Raster Calculator in a Standalone Python Script

I have a directory with binary raster files (1 band only) which I need to add in a standalone python script. The problem is the rasters have different number of rows and columns and different ...
61 views

### How to find the sum of many raster files in arcmap?

I have a list of 576 raster files for which I need to find the SUM. Obviously using raster calculator one by one would be tedious. Any easy script in Arcpy to do this?
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### QGIS 2.8.6 raster calculator: cannot select cells which are below a value in a raster

I have a distance raster map in tif format and I am trying to generate a binary raster where cells below 200m are asigned value 1 and cells above that value are 0. I've converted the distance raster ...
53 views

### problem with raster calculator results when subtracting two rasters with different resolutions

I have two elevation datasets which I am trying to subtract to calculate thickness (using ArcGIS raster calculator). The first datset is a tif which is oriented north-south and has a cell size of 5 ft ...
34 views

### Looking for a raster calculator C# class

I am developing an application using C# and dotspatial. I need to performs raster calculation a lot..I need a library which helps me to do it..Do you know any library for this purpose? The library ...
48 views

### Addition of rasters using raster calculator

I have five classes of rivers as different rasters. and I want to add them all in a new raster file using raster calculator. But when I do this, it creates 16 types of classes, while I want am ...
23 views

### Recover failed raster calculator operation QGIS

Users can recover their raster calculator algorithms via the "results" panel in ArcMap (i.e., analogous to viewing one's "history"). Is there a similar function in QGIS? In other words, is there a ...
70 views

### How to prevent RGB composite flatten to 1 band after raster calculation

I have a series of landsat wanting to process in raster calculator, but after doing the tool it happened these output images only contain one single band. They used to be RGB 3-band images. It is on ...
77 views

### Calculating percentage of cells which are lower than site in Grass GIS?

In GRASS GIS: I have a shapefile with 300 hundred of sites (with height values for each point), and want to calculate the percentage or number of cells (of a given DEM) which are lower than the site'...
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### QGIS Zonal Stats Plugin - Python Console - compute one specific statistic

I think this is more of a syntax problem that I have here. But I am absolutely not able to figure it out. On a different Linux machine I got the following working: zoneStat = QgsZonalStatistics (...
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### QGIS Raster Calculator syntax

I have tried this several different ways and get lots of NaN. I need to specify that in my raster 'test1', I want a certain set of values to equal 1 and the rest to equal zero. For instance, I want 1,...
117 views

### Huge file size after averaging two rasters

After I average two raster files (singleband gray, initial size ~700MB each) through QgsRasterCalculator() with formula "Raster1@1/2 + Raster2@1/2" the size of the resulting file is 2.9GB. Is there ...
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### How do I change my “no data” values to get “true” values in raster calculator in Qgis

I have two rasters and I want to subtract the values from one of the layers. The first raster is a altitude raster and the second raster is depth values for a lake. I would like to subtract the depth ...
42 views

### ArcGIS merge/unite two rasters with same extent with RasterCalculator

I've a problem with the ArcGIS Raster Calculator: I have two 2-Bit Rasters with the same extent, the only data stored in it are 1-values and NoData. Now I want to combine this two Rasters: If in ...
83 views

### Convert 0's to NoData in QGIS Raster Calculator [duplicate]

What is the easiest way to convert cells with a value of 0 to NoData in QGIS Raster Calculator?
92 views

### Sequentially distilling several raster data sets into final map based on first time pixel’s value was greater than zero?

I have 120 daily data sets that contain a value only when a threshold temperature is exceeded. If the threshold has been reached that pixel was assigned a value indicating the day it occurred (the ...
47 views

### Changing raster value based on point feature

I am working on some landslide modeling. Within ArcMap I have a raster layer, representing the area of the county I am working in, and a point layer that shows landslide locations. I reclassified ...
102 views

### Using Raster calculator in Modelbuilder ArcGis 10

I am using Modelbuilder to calculate several rasters with different parameters for each grid cell. One of the final steps is to calculate the log of one of the rasters using Raster calculator. ...
36 views

### Polygon to raster. How to keep same values?

I have a polygon with values 3, 6, 9, 12, 15, 18, 21, 24, 27 an 30. These are the time it takes for the firetruck to reach certain destinations. Now i want to compare these to another raster that have ...
58 views

### I have slope raster and that is categorized with slope in percentage(%) but my script not successful

I have slope raster and that is categorized with slope in percentage(%) my condition is if slope <= 1 then m = 0.2 1 < slope <= 3 then m = ...
59 views

### Add value to entire column in attributes

Is there a way to add a value to the entire column? I don't think i can use raster calculator because it's a text i want to add, the letter "B". Here is a picture. This is what happends when i use ...
86 views

### Using attribute table values as input for raster calculation - modelbuilder and iteration

I have multiple years of daily XY point shapefiles that contains multiple attributes. I would like to choose one attribute from my XY point and perform a raster calculation with that value and apply ...
55 views

### Performing Raster Algebra using DotSpatial?

I want to perform some Raster Algebra using DotSpatial. Is there any solution for it? Or any examples? this is a class which I am developing to perform raster algabra but as you see there is some ...
41 views

### Raster calculator iteration

I have a set of rasters within a file gdb in which are of continuous values (NDVI). I am trying to build an attribute table for each raster in order to reclassify into either 1 or 2 (water or land). I ...
60 views

### Polarity of Slope raster for use in Multi Criteria Evalution

I'm looking to use a slope raster in a MCE however i am struggling to ensure it has the correct polarity. The polarity of my other two layers is high values = good and low values = bad. The slope ...
79 views

### Using decimals in ArcGIS Raster Calculator tool?

I would like to create a new raster by using the following regression equation in the Raster Calculator tool in ArcGIS 10.3: Outputras=0,000826345+(0,000203494*"Roads_density.tif") ("Roads_density....
164 views

### how to get max and min from a raster using arcpy?

I have a land surface temperature raster file and I want the max and min of it. minLSTresult = arcpy.GetRasterProperties_management(raster_result, "MINIMUM") minLST = minLSTresult.getOutput(0) ...
32 views

### How to iterate a raster calculator with a change in the input raster and in the values calculated? Than, how to put the results in a table?

What I do without iteration is the following: Change radiance to reflectance for band 3 with raster calculator Samething as #1 on band 4 (the values in the formula are different from #1) Calculate ...
81 views

### How to chain several conditions in SAGA raster calculator

Is there a way to use an AND statement within SAGA raster calculator expression to include several conditions in the same operation? I have 3 rasters, the statment should be: If (A = 0 and B = 0),...
186 views

### SAGA tools in QGIS only allow save as .sdat file?

I'm just beginning to learn how to use SAGA 2.1.2 tools within QGIS 2.12.1 on a Windows 7 64 bit computer by working through exercises in Mastering QGIS by Menke et al. (https://www.packtpub.com/...
57 views

### Raster Calculator subtraction giving wrong difference

I'm performing a pretty simple subtraction: The values of the resulting raster are correct for some pixels: But many pixels are calculated wrong: Which settings do I have to change to get ...
67 views

### Standardising DEM raster for a MCE

I'm trying to complete a Multi-Criteria Evaluation for an MSc assessment and am in the process of standardising my factor maps. Unfortunately, my DEM layer (ASCII file) keeps changing from this: ...