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

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15 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 ...
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1answer
25 views

How to calculate raster data in vector area?

I have two layers. One is a layer of USA ecoregions (there are 9 ecoregions). It is not raster (so it's vector?). The other layer is the National Land Use Data set (so I know where there's ...
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2answers
34 views

How to use OR in a CON statement, in the ArcGIS Raster Calculator?

I'm trying to compare two rasters, and create an output based on a formula like: if raster1 > 10 or raster2 < 20 then raster3 = 30 How can I specify the OR in the raster calculator's CON ...
3
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0answers
27 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, ...
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1answer
33 views

Making color map in ArcGIS for Desktop?

I have bands 2, 3, 4, and 5 map. How can I use these to make a color map in ArcGIS 10.1 for Desktop? Can you give me steps? Also I want to make attribute table of colormap. How this can be ...
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1answer
24 views

QGIS raster calculator using abs() function

Is it possible to use the Abs() function in the raster calculator in QGIS? I've tried it, but it didn't work.
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1answer
32 views

ArcGIS Raster Calculator output raster has one band but cannot build attribute table?

I built a raster using the raster calculator of ArcGIS 10.1 for Desktop. The properties of the output raster ("usle_1") indicate that this raster has one band. There is no attribute table but I ...
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2answers
35 views

Get raster expression

In Arcmap I have made a new raster with ArcToolBox -> Spatial Analyst Tools -> Map Algebra -> raster calculator. Now, months later, I have forgotten the source formula expression. How can I ...
2
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1answer
26 views

Adding additional parameters to image classification in ArcGIS for Desktop?

I have an RGB ortho rectified Image and I have another grid data with Elevation values. However, an image with only three bands does not give a good classification of landcover, so it is important ...
2
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1answer
50 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 ...
7
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2answers
88 views

Rules of Nodata value?

What are the arithmetic rules that govern Nodata values? Regardless of how these null values are defined? I am using ArcMap Raster Calculator. I am thinking specifically of operations like 1*Nodata ...
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1answer
35 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.
3
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1answer
71 views

SAGA raster calculator, ifelse command syntax problem?

I am trying to get the saga raster calculator in QGIS to spit out all values of a raster that are inferior to 10, and make all other values zero. I think the syntax is correct but I keep getting the ...
1
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0answers
24 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 ...
2
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1answer
53 views

Conditional Statements in QGIS raster calculator?

What is the equivalent statement of the following expression in the QGIS raster calculator? Con(((Abs("DEM" - "FSMin") > 120) | (Abs("DEM" - "FSMax") > 120)), 1, 0) I have no problem ...
3
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1answer
72 views

Running focal statistic with iterator in ModelBuilder?

I need to extent the Value of a grid (water mirror elevation) within the nodata area until reaching a specific barrier (the limit of the watershed), in ArcGIS 10.2 for Desktop. I am using this: ...
3
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2answers
72 views

Use Values from Raster Statistics (e.g. sum of all cells) in Raster Calculator

I need to do calculations on raster layers which require the sum of all cells of the raster. I've used the zonal statistics tool for that but it gets a little annoying to do those extra steps (run the ...
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0answers
32 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
49 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 ...
0
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1answer
40 views

Raster Calculator Blurring Image Results

I am trying to run a NDVI analysis using raster calculator on Arg Map 10.2.1 and the results create blurry or bleeding image, almost as if the map has been dipped in water. I am using the default ...
0
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1answer
70 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 ...
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0answers
45 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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1answer
37 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
51 views

QGIS – Raster Calculator: Using flat (no data) areas of an aspect-raster in the raster calculator

I´m playing around with the Raster tools, following more or less the qgis-tutorial but using my own data. When I calculate the aspect of a DEM, flat areas are (logically) left without data. However, ...
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1answer
79 views

Raster map calculation

I figured out a way to filter a raster by using the r.mapcalculator or the raster calculator. The problem is that I have to use Qgis 2.2 because some of my models doesn't work with 2.4. In 2.2 the ...
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1answer
82 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
64 views

How to convert raster negetive pixel value to positive

I was working on ground water Level. I used raster math minus function and the Output raster grid data contains negetive cell values. ma resulting raster contains values ranges from High : 0,187477 ...
0
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2answers
88 views

Error in which.max() : not yet implemented for large objects in R

I am going to create raster by Julian day that observed maximum value of NDVI within a single year. Actually, I want to know which julian day (or raster) has max value in each cells and get result by ...
0
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2answers
89 views

How to create raster map by day that observed maximum NDVI from multiple raster data in R?

I have 11 NDVI raster data, representing single summer. I want to create raster by day (Julian day or name of raster) that observed maximum value. In other words, I want to know which day (which ...
1
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1answer
70 views

Calculating field length in certain directions (raster)

Currently I'm working on winderosion. For my purpose I like to calculate the length of agricultural fields in certain wind direction. I would like to do it for raster. To be more precise: I have ...
0
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1answer
68 views

Cause of ArcGIS Raster Calculator Parsing error <type 'exceptions.SyntaxError'>: invalid syntax?

This is my first attempt at much code in the raster calculator of ArcMap 10.0, but I think I'm close. I have nine rasters (A-I below) and want a new raster with value = 1 where any of the rasters ...
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2answers
98 views

DEM mosaic: gaps

I have generated DEMs (bare earth) from Lidar data. For computational reasons, I have processed via ArcGis the lidar files in chunks, so I came up with different single DEMs. After, I used "Mosaic to ...
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1answer
86 views

QGIS Slope Classification Issues

I am very new to QGIS for the primary purpose of creating a slopes layer so we know where slopes are above 15% or 20% or whatever we finally decide. I have used our DEM to create a slope geotif and ...
0
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1answer
51 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?
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1answer
76 views

QGIS raster calculator manual or help

There is plenty unknown about how to use raster calculator, for example: how to write NODATA (Null) value in expression is it possible to use within (polygonLayerName) to clip result between shown ...
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0answers
53 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 = ...
1
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1answer
68 views

Need to calculate values for a cell based on surrounding landscape

I have a raster file with the urban development of a county mapped out (values: 1=urban 0=not urban). I also have a raster file with several blocks of forested land, each block of land has its own ...
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2answers
169 views

Replacing raster values in one raster with another raster in QGIS … how to?

I have a raster (DEM) and want to replace a few cell's values with the values from another raster in QGIS. I would have done this with the "over" tool in the raster calculator in ArcGIS. Specifics: ...
0
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2answers
121 views

Change detection with raster calculator

After applying the Diff operator of the raster calculator in arcgis to view changes in land use, would like to see the areas of increased and areas of decreased. This is possible using the raster ...
0
votes
1answer
77 views

How to calculate cumulative sum conditionally across raster?

I don't know if this is possible without coding, but I need to: Create a raster file that, for each value in the input raster, sums all pixel values across the entire extent that are less than or ...
0
votes
1answer
123 views

How to compare two rasters and reclass the greater value(python script)?

I am working on an assignment that requires us to reclass a raster(via python) from two rasters. We need to compare the power received at one cell(on raster1) and compare it to the same cell on raster ...
2
votes
1answer
57 views

Translating to Raster Calculator?

I am taking the Learning Spatial Analyst course, which is very good but written for Version 9. I and my students are using Version 10, so some of the syntax for Raster Calculator have changed. Can ...
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1answer
73 views

Raster Calculator Workaround in Arcpy for Suitabiliy Analysis

This is my first attempt at a complex stand alone python code. I am self teaching the arcpy module, well at least attempting to. I am having a great deal of difficulty getting my site suitability ...
0
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1answer
30 views

IF (there are three or more developed cells in the Moore Neighbourhood of a cell) THEN (the cell is developed)

Hi I need to create an expression for that principle, so far I have figured out CON ("FocalStatisticsSum" >= 3,"FocalStatisticsSum"="FocalStatisticsSum"+1) Although I pretty sure I am missing ...
1
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1answer
108 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 ...
0
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1answer
79 views

Define a circular neighborhood for a custom raster calculator function? [closed]

I have a 1 meter resolution raster containing values from 0-3 which represent increasing levels of habitat suitability. I need to identify circular regions that have contiguous pixel values. For ...
0
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0answers
193 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 ...
0
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1answer
22 views

Error 000539 - Band_# not defined

I'm trying to do an NDVI analysis of a some World View 2 imagery. It seems no matter what if I enter the term Band_# for any of the 8 bands I get the same error.
0
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2answers
107 views

Find the minimum elevation pixels from an elevation raster using arcpy

I want to create a python script to find the minimum elevation pixels from an elevation raster (aster,srtm) using arcpy and arcmap 10.1. The purpose is to reclassify these pixels. I have tried but I ...
3
votes
1answer
124 views

Expand raster extent and set expanded values using nearest neighbor sampling

I have run a hydrodynamic model which has given me a grid of surface elevations throughout a bay. I am trying to process the results in ArcMap (or QGIS if needed). My goal is to take the current grid ...