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

learn more… | top users | synonyms

1
vote
2answers
44 views

Using QgsRasterCalculator

I'm trying to make a sum of n rasters and create a new one using QgsRasterClaculator, the problem is, every time the code reaches processCalculation, it makes QGis close and create a dump file. I ...
5
votes
1answer
257 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
37 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 ...
3
votes
1answer
314 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
votes
1answer
22 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
75 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 ...
1
vote
1answer
40 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.
1
vote
1answer
61 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
184 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 ...
1
vote
1answer
251 views

Floating point calculations in QGIS

How do I manage floating point calculations in QGIS? I have carried out 3 consecutive calculations on landsat bands. I end up with 32 bit floating point rasters on which I can't carry out a 4th ...
0
votes
1answer
54 views

Modifying raster values in a zone with a math expression

I'm currently doing an SIG project with the goal of calculating groundwater volumes in chalk and silex residuals aquifers. I have point data of underground water, chalk roof, and floor elevations, as ...
0
votes
1answer
96 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
votes
1answer
54 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
0
votes
1answer
80 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, ...
0
votes
1answer
135 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 ...
0
votes
1answer
23 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
votes
1answer
59 views

Setting up Raster Calculater for QGIS Python Console: ImportError?

I'm trying to follow the instructions here How to evaluate raster calculator expressions from the console? to set up the python console to to use the raster calculator. I tried: from qgis.analysis ...
0
votes
1answer
44 views

Isolate And Save Raster Features From Existing Multivalue Raster Map

I have Cyprus Corine map with 44 different types of land use. I want to run a raster calculator query or any other way to isolate the areas with codes 10 to 22 and 26 to 34, all other values 1 to 44 ...
4
votes
0answers
103 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
64 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
votes
0answers
34 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
0answers
89 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
votes
0answers
37 views

Using iterator in ModelBuilder for groups of rasters

I'm trying to do some raster calculations on Landsat imagery in ModelBuilder. I'm calculating basic indices using Raster Calculator followed by Zonal Statistics. The resulting tables are merged ...
2
votes
0answers
73 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
2
votes
0answers
79 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
votes
0answers
60 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
vote
0answers
70 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 ...
1
vote
0answers
38 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 ...
1
vote
0answers
36 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 ...
1
vote
0answers
79 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)) ...
1
vote
0answers
66 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 ...
1
vote
0answers
114 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, ...
1
vote
0answers
75 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 ...
1
vote
0answers
30 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 ...
1
vote
0answers
389 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 ...
1
vote
0answers
393 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
votes
0answers
30 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
votes
0answers
26 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
votes
0answers
37 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 ...
0
votes
0answers
50 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
votes
0answers
30 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
votes
0answers
39 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
votes
0answers
70 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 = ...
0
votes
0answers
289 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
votes
0answers
66 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 ...
0
votes
0answers
59 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 ...
0
votes
0answers
29 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?
0
votes
0answers
40 views

How to find difference between terrain and groundwater potential map?

I want to find the difference between a terrain map and groundwater potential map to show where it is possible to apply SUDS (sustainable drainage systems) but the units makes no sense. First in ...
0
votes
0answers
77 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 ...
0
votes
0answers
148 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 ...