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

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5
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1answer
360 views

Calculating Topographic Exposure with Raster Calculator

I need you help trying to calculate Topographic Exposure (TOPEX) on a DEM in ArcGIS. I am trying to figure out wind exposure on a DEM with 25m cells. There is a great blog post where someone explains ...
4
votes
1answer
57 views

Iterate through rasters in subfolders using Model Builder

I have a directory folder of precipitation data; within this folder are subfolders for years 1901-2014. In each of these subfolders are 12 .asc grid files; each file represents a month of the year ...
4
votes
1answer
45 views

Raising raster to a power gives no data values

When performing the following operation in QGIS Raster calculator: 10 ^ (("20091201_20100101_chl_modis_malvinas_ns@1" * 0.0000581)-2) I get no dada values for every cell where I should get < 1, ...
3
votes
1answer
337 views

An error in raster calculator in Arcgis

I wrote and ran this formula in raster calculator in ARCGIS. But the following error gets me into trouble. Does anyone have a suggestion to overcome this? Here is the formula I wrote and the error ...
2
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1answer
25 views

How to calculate values in a 3*3 matrix using raster calculator?

How to manipulate a raster values in a 3 X 3 matrix.. using raster calculator or any other method e.g. to find out how many cells are there in a 3 X 3 matrix having cell values less than the center ...
2
votes
1answer
92 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 ...
2
votes
1answer
415 views

Help with scripts for processing raster files with the raster calculator in QGIS

I am trying to process some raster files using python scripts in Qgis 2.20, and I have been having trouble finding any documentation on using raster calculator in scripts being run in the processing ...
1
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1answer
52 views

QGIS SAGA Raster Calculator

I am using SAGA --> Grid Calculus --> Raster Calculator on QGIS version 2.6. The formula I am using is: ifelse(gt(a,0), (a), b) where a is my layer with values in a greater extent than that of b. ...
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1answer
22 views

Raster layer - changing values in raster cells

I have a lot of cells in a raster layer (GeoTIFF) with a -9999 value in it. I would like to update that values to 0. I mean, in vectorial layers would be something like: CASE WHEN band1=-9999 THEN 0 ...
1
vote
1answer
30 views

QGIS Raster Calculator, joining two raster

In QGIS raster calculator I do: Plus (+) And I get: The red circle in the middle is like cut in the result, QGIS it's not adding every pixel on each raster, it makes a kind of ...
1
vote
1answer
55 views

R.Mapcalc giving only blank maps as result

No matter what function I put in the r.mapcalc in the GRASS GUI I get a blank map full of null values. I even tried DEM+0 (I can see my DEM) and this also yielded a blank map.
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vote
1answer
70 views

How do I replace cell values of a raster using values of another raster with differing extent?

I have two rasters (raster1 and raster2). The raster1 extent is smaller than raster2. I want to replace the value of raster2 pixels using raster1 pixels. How can I replace the values?
1
vote
1answer
229 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 ...
5
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0answers
148 views

Focal Statistics for Special Neighborhood

I'm looking to calculate focal statistics for each cell of a raster, within a neighborhood of a specified criteria. Background - I have three binary rasters, each representing a single vegetation ...
3
votes
0answers
93 views

Single Tree detection

I was wondering how I could extract "crown area" of single trees in a forest from a high-resolution image with only 3 band (RGB) in ArcMap. ( No NIR to use NDVI as any threshold). I need a fast ...
3
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0answers
97 views

Creating a new raster based on pixel value of original raster using raster calculator but new layer is not evident

I am trying to create a new raster based on a current raster (w001001 - NVIS) which has one paletted band, with palette values ranging from 1 to 29, with each palette/value representing a vegetation ...
2
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0answers
103 views

Merge Raster Layers with Raster Calculator

I am looking to merge three raster layers together, we are only allowed to use the Raster Calculator tool in Spatial Analyst, ArcToolBox. Using ArcMap 10.2
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0answers
134 views

Why do comparisons in QGIS 2.4.0 Raster Calculator return -3.40282e+38 aka no_data?

I tried to use comparisons as conditional statements in QGIS 2.4.0 raster calculator. My statement is: (a < 230) * 230 + (a >= 230) * a The expected result is raster a with all values lower ...
2
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0answers
61 views

How do I make a path cross the most possible classes in a raster?

I want to create a function and possibly use Arcmap tools to create something similar to Cost Path. Instead of just choosing the LCP, it must cross through the most different integers. Let's say I ...
1
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0answers
14 views

SAGA Raster Calculator, ifelse doesn't return specified value exactly

First time caller, long time listener.... I am using the SAGA Raster Calculator in QGIS 2.6 to change NaN values to zero and that part is working great, however the specified 'if' value is being ...
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0answers
15 views

How to calculate the Vertical Distance to Channel Network in ArcGis?

In Saga there is the tool "Vertical Distance to Channel Network". Is there a way to produce the same data in ArcGIs? With con("flowacc" > xx, 1) I was able to create the Channel Network. I am ...
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0answers
41 views

Assigning score to raster based on cell overlap with other raster and field value

I have a set of rasters that I've assigned scores to individually (scored based predominantly on values of other fields). The scoring scale is the same for all rasters, but the factors that determine ...
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0answers
60 views

Creating a Raster of Road Distance to Point

I am using QGIS 2.6. This question is in two related parts: I'm trying to create a raster of travel time from one point to another point travelling via the road system. Each raster pixel will roughly ...
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0answers
115 views

How to Normalize or rescale the NDVI raster image

I have processed my landsat band 3 and band 4 of different years to derive NDVI values the possible values of Normalized difference vegetation index is -1.0 to +1.0. The bands were atmospherically ...
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0answers
52 views

Raster calculation with string in modeler

In my model I have one raster file and also a string input (factor for further calculation). I tried to use the grass r.mapcalculator where I can find the raster and also the string input. I tried to ...
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0answers
43 views

Multiply Rasters with Scalar Numbers as Input in QGIS Modeler

I built a little model in the QGIS modelbuilder which uses the raster calculator with the command gt(a,threshold) I need to run the model with varying thresholds from 2 to 30 so it would be ...
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0answers
193 views

Error 000539 I am new to Raster Calculator and can not figure out what is going wrong

I am new to Arc and 10.2 but can not seem to figure out why this won't work. Executing: RasterCalculator Con(("SLOPE_SLO.tif" >= .015) & ("SLOPE_SLO.tif" <= .15,1,0)) ...
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0answers
80 views

Raster Calculator

I have a slope dataset. How do I calculate the real surface area for this slope dataset using the raster calculator. This is the example I was given: orthogonal area of a raster cell in square ...
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0answers
201 views

plug logistic regression equation into Raster Calculator when one predictor is nominal

I am conducting a study that aims at building a Logistic Regression model for land productivity quality (binary dependent variable: good, no good) using different predictors such as slope, elevation, ...
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0answers
85 views

How to produce a hazard map using slope and geology information

for my project I need to display a landscape's susceptibility to erosion. I created a slope-map out of my DEM and added the bedrock geology as a polygon-feature shapefile. Now I want to tell ArcGIS ...
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0answers
41 views

Cell Statistics in QGIS

Cell Statistics in ArcGIS will calculate the mean (or statistic of choice) among multiple rasters on a cell-by-call basis. Can QGIS do this? If so, how?
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32 views

Layers and variables are not coming out in the raster calculator tool window

I have many shapefiles in the table of content but layers and variables are not coming out in the raster calculator tool window. I placed the cursor the left of the Raster Calculator window, dragged ...
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0answers
437 views

How To calculate raster land cover inside overlapping buffer zones?

I am working with a raster land cover file that consists of several land cover types (e.g. forest, buildings, grass ect.) in total there is 40 different land cover types. I have 1200 bufferzonen ...
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0answers
440 views

Raster calculator error 000539 - cannot create weak reference to 'classobj' object

I was - like many times before - trying to clip a raster with the raster calculator (raster * 1 with shapefiles as mask). Now - the following error keeps popping up: ERROR 000539: Error running ...
0
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0answers
16 views

Computing View Distance in One Direction from Point on Elevation Raster in PostGIS?

I'm a software developer just getting into GIS, so please forgive me if I don't use proper lingo, or if I use proper lingo incorrectly! I have a raster of elevation data. For a given point in the ...
0
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0answers
34 views

apply gdal to calculate raster that is already in qgis raster calculator

I am using the following code in qgis to calculate some raster.It is not giving the correct result as it is in arcpy.I want to apply same in gdal.Can anyone help me how to use the gdal api.Please give ...
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0answers
4 views

Implementing GLMMs in ArcGIS

I am looking to create a predictive model in ArcGIS. I have done this previously with glm with poisson distribution and found it relatively straightforward in raster calculator e.g. exp(intercept + ...
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0answers
38 views

Stream buffer and reclassification

![euclidean distance and the layout highlighted(but they are two different layers)][2]I have this task to perform for hydrology analysis as presented below: DETERMINATION OF STREAM NETWORK AND ...
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0answers
61 views

QGIS 2.4; How to convert float raster to integer raster

I am using Normalize difference vegetation index (NDVI) derived from the landsat satellite band 3 and band 4 that have float values ranges from -1.0 to 1.0. I want to see the attribute table that is ...
0
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0answers
27 views

How can i perform area calculations in a raster file?

I would like to know if is possible and how can i calculate all areas or parts of it in one raster? Can i do it using the raster calculator? All help is appreciated, Best regards
0
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42 views

Raster Calculator returning nodata for overlaying cells

I used raster calculator to divide two rasters setting the environment to intersection of inputs. The output has a nodata value in a cell where these two rasters clearly intersect. Any suggestions ...
0
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0answers
48 views

byte swap a mosaic raster

I'm getting into trouble to byte swap a raster. I'm using two DEM rasters that I mosaic using the function "mosaic to new raster". The new raster I get is called "mosaic". The cell range then shift ...
0
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0answers
78 views

Normalize the NDVI raster 0-255

NDVI values raster computed by using the band 3 and band 4 reflectance values b4-b3/b4+b3. The output raster is of 32bit type formate although the possible ranges that shows in statistics parameter ...
0
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0answers
50 views

Trouble with reading Leaf area index (LAI) Modis on QGIS

I am having trouble reading my Modis LAI data on QGIS. I imported my Modis hdf files and I used the QGIS raster calculator to apply the scale factor and all I get is a blank gray tile. My goal is to ...
0
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0answers
50 views

Problem with Raster Calculator in Model Builder

I have created a model which repeatedly uses the raster calculator. My problem is that unlike that of the other tools, the output name of the raster calculator does not change. This means that I can ...
0
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0answers
94 views

Arcpy raster calculation producing random no data cell in output

I've been trying to get the raster calculation below to work using python: import arcpy from arcpy import env import os from arcpy.sa import * arcpy.CheckOutExtension("spatial") KSat_mm = ...
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0answers
83 views

Extract raster values under under each polygon buffer in qgis

In qGIS: I have raster file and >100 points. I constructed buffers polygons (vector-->geoprocessing-->buffer) around each of the points. Than I clipped (raster-->extraction-->clipper) the raster file ...
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0answers
60 views

Efficient manner to buffer streams with multiple attributes?

I need to buffer a very large, complex hydro vector layer based on different water quality designations and surrounding slope. Different water quality classifications have different buffer ...
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0answers
84 views

How to calculate specified region area with raster in ArcGIS Engine?

By using the "Image classification" tool we can classify the raster image by "supervised classification",but how to calculate their area? I mean, for example, in regard for a produced class '4', how ...
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0answers
174 views

Why does the SAGA raster calculator fail when used in a Processing model?

I have a problem with the modeler and the saga raster calculator. When I'm using the raster caculator without the modeler it works fine. When I'm using the saga raster calculator in my model I always ...