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

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1answer
24 views

Problem with algebra formulas for work with gdal_calc.py

I'm trying to update some values of a raster based on another raster. 1st raster (A): landuse data (values from 10 to 240) 2nd raster (B): mask data (only nodata values and a given value, for ...
1
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1answer
108 views

How to reclassify raster data that falls within a polygon

Thansk for your response Okay so I will reword my question more clearly I'm currently using ArcGIS 10. My task is to map forest cover with the image classification tool. The problem is some of the ...
0
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2answers
296 views

Remove sections, defined by a line or polygon, from a raster in QGIS

(QGIS 2.6.0 on Windows.) I have created a raster layer of heights using the TIN interpolate function. I also have another raster layer with more accurate information on the height of particular areas ...
1
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1answer
186 views

How I can sum 360 raster files in a folder with the Arcgis raster calculator?

In a folder I have 360 precipitation raster files and I want to sum them all to the raster calculator
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1answer
15 views

combining rasters without losing their values? [closed]

Using ArcMap 10.3.1 I have 4 different rasters with values from 1- 4 (i.e raster file is 1 or no data, 2 or no data, 3 or no data, or 4 and no data). they each cover a land use category. I'm ...
3
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1answer
41 views

unexpected output from raster calculator function

Working in ArcMap, I am trying to convert the logit values in raster into their actual probabilities (logistic regression,) using the following function: 1/(1+Exp(-"sn_topo_poly_log")) Ive used this ...
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0answers
16 views

problem with raster calculator syntax [closed]

I am trying to build a raster representing the output from a logistic regression model. i keep getting syntax errors. heres the script: -2.41-(15.97 * "Topographic_Predictors\wadem10m_annsolrad") - ...
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1answer
17 views

Iterate variables in Con statement in Raster Calculator- model builder

I have this formula which works fine in raster calculator on its own. Here is a simplified version of it: Con((("Trial_analysis\winter_pm" == 2)) & ("Wind_directions\winter_pm_WD" <=b) & ...
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2answers
36 views

Combining non-overlapping binary rasters with ArcGIS Raster Calculator?

The issues I keep seeing depend on unique combinations of values. I have three rocktype raster layers for area and they are edge-to-edge (they do not overlap). They each have "VALUE" fields and ...
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1answer
40 views

Constructing LS factor for RUSLE without outliers using ArcGIS for Desktop?

I'm using the following formula in RUSLE via raster calculator to obtain a LS factor Power(Flowacc)*1/22.1,.4)*Power(sin(slope)*.01745/.09,1.4)*1.4 My expected outcome is a raster from 0 to ...
1
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1answer
565 views

Raster vs. Raster Scatter Plot in ArcGIS

I created two raster datasets from the same world view 2 image. One dataset is NDVI, the other is a normalized surface water index (NDSWI). I would like to create a scatter plot for a pixel by pixel ...
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20 views

Curve Number equation

I have a floating point raster of Curve Numbers (70-91) and I'm attempting to use the curve number equation to create a weight raster for flow accumulation, to determine runoff for a single rainfall ...
1
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1answer
45 views

Raster calculator fails with large raster in QGIS

I'm working in QGIS 2.14.1 with a DEM ranging from 200 feet to 1600 feet elevation called "dem_3m_Zft1b" (geotiff, 16822 X 33349 cells, No-data =-9999) If I enter "dem_3m_Zft1b" > 0 in the ...
0
votes
1answer
108 views

QGIS raster calculator wrong output

I am trying to create a mask from a DEM (SRTM tile) using raster calculator in QGIS. I have performed the same operation in ver 2.6 with no problem but in the current version the output is incorrect. ...
1
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1answer
406 views

PostGIS ST_MapAlgebra Assistance

I would like to perform the equivalent of the below ArcGIS raster calculator equation in PostGIS using the ST_MapAlgebra function and return it as a tif using ST_AsTIFF. Con(("Sol_gain_clipped.tif" ...
1
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1answer
34 views

ArcMap raster calculator error 000539

Using ArcMap 10.3, I am trying to perform map algebra on a raster with 2013 annual PRISM precipitation for the U.S. (http://prism.oregonstate.edu/recent/). The raster has 1 band an is floating point. ...
3
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0answers
41 views

Mapping habitat suitability using ArcGIS for Desktop?

I have been having somewhat of an issue recently with one of my projections. I am currently trying to map out the preferable habitat for a species in Arcgis. To do this, I performed a GLMM in R and ...
1
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1answer
527 views

Raster Calculator error

I'm trying to use the Raster Calculator inside ModelBuilder to get rid of null values, but I'm hitting a snag. I'm using the expression: ...
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2answers
32 views

Recalculating raster based in number of cells?

I am working with binary rasters of fish species distributions (1=presence, 2=absence). I am looking to recalculate each raster in this way: Count the number of cells with value 1. Divide: 1/Number ...
1
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1answer
21 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 ...
0
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0answers
32 views

Create Cost Surface Raster with slope as percentage of total costs

I know there is a similar question on this website (How to Create Cost Surface Raster for Least Cost Path Analysis?) , but I couldn't find the answer that I'm looking for. I'm currently working with ...
2
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1answer
57 views

Is QGIS Raster calculator faulty?

I am trying to perform some rounding operations on rasters. I have used GDAL to convert the raster to an integer which is fine but now I want to /100 which should be simple in raster calculator but ...
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1answer
221 views

I want to compare multiple raster layers against each other to identify changes in pixel values over time

I am using LAI values to assess vegetation growth over large areas. I want to be able to identify areas that are doing well and areas that are decreasing based on the changes in pixel values. Ideally ...
0
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2answers
91 views

Syntax Raster Calculator

I have never worked with the raster calculator before and I can't solve my problem. There are two raster datasets. One contains roads ( "closed", "in use", "under construction") and the other dataset ...
1
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1answer
90 views

Conditional statement in raster calculator - ArcMap

I'm Just wondering how to incorporate a conditional statement basically to say: if value in raster >= 128, then put in new raster, otherwise make the values null. Basically the purpose of this is ...
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2answers
73 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. ...
0
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1answer
131 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 ...
4
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2answers
2k views

Specify a field in attribute table with raster calculator

How can I specify the attribute field to use in the raster calculator of ArcMap 10.2? In 9.x, I used the dot notation. i.e. To use the "New_Value" field, I could do the following: ...
0
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1answer
48 views

Can I multiply fractions in map algebra?

I have a couple of rasters that show % of success in different things. I want to calculate the overall probability of success. The numerical values are integers so they represent the percentage. This ...
3
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3answers
200 views

Flow Accumulation Python or MATLAB Script

does anyone have any resources for scripting the D8 flow accumulation in Python or MATLAB after obtaining the flow direction values and filling in 'sinks' and 'flats'? I am trying to understand the ...
4
votes
1answer
254 views

How to compute NDSI in ArcGIS for Desktop?

How do I compute a Normalized Difference Snow Index (NDSI) in ArcGIS's Raster Calculator? I have a Landsat 8 scene (hdf4 format) that contains derived surface reflectance band-by-band. Each band is a ...
2
votes
2answers
795 views

Trying to run raster calculator to build an expression for ls factor

I am trying to run a raster calculator, but it failed. I believe that ArcGIS 10 does not understand when I use the variable resolution. What do I need to put in its place? I took the equation from ...
0
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1answer
272 views

Creating an R factor raster in RUSLE Soil Loss equation with multiple input rasters

I am attempting to obtain the rainfall erosivity "R" factor for the RUSLE Soil Loss equation using rainfall PRISM 30 year history data. I have both monthly and annual data that comes into ArcMap as ...
2
votes
1answer
34 views

Why does SAGA raster calculator interpolate between cell values?

I am hoping for a bit of help with a raster calculator issue that is puzzling me. I have a raster layer with a series of integer values (classes) for each cell. I am trying to use the SAGA Raster ...
6
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3answers
6k views

How to standardize raster output from 0 to 100 using raster algebra?

I am working on generating an integrated moisture index based on the following equation: IMI = (hill shade * 0.5) + (curvature * 0.15) + (flow accumulation * 0.35) Iverson et al. 1997 Another ...
4
votes
1answer
316 views

Raster Calculator Iteration in ModelBuilder?

I have a large number of rasters and I want to add 1 to each of them (e.g. each raster's values currently range from 0 to 1, and I want to make them range from 1 to 2). I believe ModelBuilder, using ...
0
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2answers
326 views

Issues calculating range with QGIS 2.0 raster calculator

I would like to calculate a simple range using the QGIS 2.0 Raster Calculator, but am getting strange results. I believe I am not using the correct syntax. To get all values between .003-.5, I ...
0
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1answer
29 views

raster calculator fail to sum?

I am having a question about the raster calculation as I am trying to create a tool which I want to link with my python script to sum weight rasters but if failed to do so. here is my code: #*the ...
1
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3answers
2k views

Create an X,Y latitude and longitude grid from an raster

I have a satellite image (LandSat 5), I want create a raster with X,Y coordinates, this is possible in Model Builder of ArcGis 10.0? or other option. I know that the option $$YMAP ($$XMAP) not work ...
3
votes
2answers
108 views

How to update raster pixel values based on another raster with conditions in QGIS?

I have 2 land cover rasters. I want to update parts of the first raster with values from the second using QGIS. The workflow should be like this: 1. Select values equal to 30 and 34 in the first ...
1
vote
1answer
52 views

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 ...
1
vote
1answer
50 views

Calculating maximum value in Raster Calculator of ArcGIS for Desktop?

I have MODIS NDVI data of four months and I have to calculate NDVImax. I am using the Raster Calculator of ArcGIS and have been using various algorithms like [MAX ("june2000", "july2000" , ...
2
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2answers
52 views

Using Con in Raster Calculator of ArcGIS for Desktop? [closed]

I have two images, "dvel.img" and "evi.img", and i want to extract water related pixels. The condition is: (("dvel.img" <= 0.05) & ("evi.img" <= 0.3)) I want to get an output by putting ...
3
votes
1answer
24 views

In ArcGIS raster calculator can you access the individual cells surrounding a central cell like you can in GRASS r.mapcalc

Is there a way to do the following in Raster Calculator in ArcGIS? In GRASS r.mapcalc you can access the cells surrounding the current cell by writing inputRaster[a,b] where a and b represent the ...
0
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1answer
43 views

Meaning of ERROR 000539: Error running expression: rcexec() <type 'exceptions.ImportError'>: No module named os?

In Raster Calculator using: (FocalSt_meanDEMtif5-FocalSt_minDEMtif1) / (FocalSt_maxDEMtif2-FocalSt_minDEMtif1) What is the meaning of ERROR 000539: Error running expression: rcexec() : No ...
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0answers
27 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 ...
4
votes
1answer
625 views

Performing Raster Calculator functions using Python and open source modules?

I would like to perform mathematical functions similar to those you would use Raster Calculator for in ArcMap, however I'd like to do it in Python without using the ArcpPy module. I have the osgeo ...
1
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1answer
52 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") ...
1
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1answer
43 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" * ...
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0answers
12 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 ...