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

learn more… | top users | synonyms

1
vote
1answer
398 views

QGIS SAGA Raster Calculator [closed]

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. ...
1
vote
0answers
144 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 ...
2
votes
1answer
252 views

Create Raster Surface from Points and Equations in ArcGIS

I want to use point data to create a raster surface which distributes the values over space, as defined by an equation, and NOT by interpolating. I have an equation to describe how the characteristic ...
0
votes
0answers
111 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 ...
1
vote
1answer
91 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
90 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
2answers
55 views

How to automate conversion of raster NoData values?

I am doing the work of change all null pixels to a value of -1 in the raster file X with raster calculator by using following syntax: Con(IsNull("X"),-1,"X") However, I need to do the same work on ...
1
vote
0answers
117 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 ...
1
vote
1answer
49 views

if condition is false but output is true . what is the exact expression of greater than to bands value ('mjune@1'> 99.6:)

from qgis.core import * from qgis.gui import * from qgis.analysis import QgsRasterCalculator, QgsRasterCalculatorEntry from math import * from PyQt4.QtCore import QFileInfo import os from osgeo ...
1
vote
1answer
699 views

What will happen if we subtract two raster with different cell size using Raster Calculator?

I want to subtract a topography raster with a depth raster. The problem is the two rasters have different cell size. The topography raster have a square cell size of 5, 5 while the depth raster have a ...
0
votes
0answers
555 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 ...
3
votes
2answers
600 views

Calculating average raster grid values perpendicular to a barrier and transferring values to adjacent cells

I was hoping I could get a little help for 2 questions dealing with raster datasets. I have access to ArcMap 10.2 and ArcView 3 to do this. Here is what I am trying to do: 1) I need to calculate an ...
1
vote
1answer
142 views

How to sum 10 raster bands instead of 9 from code?

I want to sum 10 raster bands but the problem is that the following code will only work for summing 9 bands, which means the output image consists of 9 bands. from qgis.core import * from qgis.gui ...
0
votes
1answer
221 views

Raster Calculator with conditional arguments?

I am trying to create a binary raster using the Raster Calculator in ArcGIS 10.2. I have a raster with ~20 different values, but I'm only interested in cells where the value = 10. I've been using the ...
1
vote
0answers
79 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 ...
1
vote
1answer
218 views

weighting and combining data sets in Raster Calculator

I`m having problems using Raster Calculator to create a final cost raster. I have to add 7 raster data sets together and multiply each of them with the correct weight. The resulting raster is ...
2
votes
1answer
51 views

If statement using QgsRasterCalculator

So in the sequence of my previous question (Can't use Raster Calculator with two different rasters), I am stuck again in my project. With my source rasters, I created 3 different outputs using ...
1
vote
3answers
188 views

Raster calculator to create single raster with 4 values from two binary rasters

I have two binary rasters showing habitat suitability (0 = unsuitable, 1 = suitable) under current and future climate scenarios. I am trying to create a raster showing: 0 = cells that are not ...
0
votes
1answer
57 views

Animating alterations to DEM based on function using ArcGIS for Desktop?

I've generated a function that alters height values of a DEM based on certain criteria. What I'm looking at doing now is animating this in ArcScene. Is there a way, in ArcGIS, for each frame to be the ...
1
vote
3answers
508 views

Can't use Raster Calculator with two different rasters

So, I have several maps like this one: And with the proximity tool and a coastline shapefile I made this output, representing the distance to shoreline: Now, I want to combine both using the ...
1
vote
1answer
39 views

Error summing 2 different rasters?

I was trying to sum two different rasters and the final outcome is an error (image attached below)? The main goal is to sum the values of each pixel in those rasters (both raster files have the same ...
2
votes
1answer
946 views

Exclude Raster Cells with Value of Zero in ArcGIS 10.2 Raster Calculator Expression

I need to perform a simple calculation in ArcGIS 10.1 Raster Calculator. I am using a raster layer that contains many cells that have a value of zero. I need to exclude these cells in the expression ...
0
votes
2answers
317 views

changing pixel values using raster calculator Qgis

How could I convert a value of 32767 to a 0 using raster calculator in QGIS?
0
votes
1answer
18 views

Rastercalc.py and Rastercalcengine.py

Is there any examples on how to use the rastercalc.py or rastercalcengine.py? And what are the purpose of these python module? Are these modules the same with gdal utilities which can be run in ...
3
votes
1answer
219 views

How to subtract out the slope (in general) of a DEM?

I'm searching for a solution process to subtract out the slope of a DEM like this: I have a high resolution DEM and want to reconstruct historical/old/not active parts of a river. The problem is ...
4
votes
2answers
745 views

Querying slope data using raster calculator: why are all results true?

I am using ArcGIS 10.2.2. From a DEM, I have created a new raster showing slope using the slope tool. The color scheme was automatically classified into 9 tiers. What I want to do is query this raster ...
5
votes
1answer
946 views

Change NODATA pixel value in raster to arbitrary value

I want to change the value in all pixels that are currently 0 to 800 in QGIS 2.6.1. 0 is listed as the no-data value in Properties > Transparency. I have unchecked the No Data Value box there. Then I ...
0
votes
1answer
648 views

How to round up/down an pixel value of a raster to a pixel value with 2 decimal places?

I have a raster (DTM) with floating points as pixel value. Now i want to round up/down the pixel values (to its next nearest value) to 2 decimal places. I use ArcGIS (with extensions) and tried the ...
4
votes
1answer
136 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
134 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 ...
-1
votes
1answer
206 views

Classify Output Raster as percentage in arcGIS

I have water supply and water demand rasters.They are both of the same cell size and spatial reference. I need the ratio of water use to water demand. Then I want to classify this output in the ...
0
votes
0answers
105 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 ...
-1
votes
1answer
304 views

Calculating average NDVI

I would like to calculate average NDVI values. I have 3 values of NDVI: high:243 low:0 high:243 low:0 high:238 low:0 How can I use a a raster calculator to calculate the average valvue
0
votes
0answers
74 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
2answers
212 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 ...
0
votes
1answer
84 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 ...
1
vote
0answers
147 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 ...
2
votes
2answers
139 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 ...
1
vote
1answer
117 views

Only run r.neighbors if cell meets criteria

This is my first time using GRASS to work with Rasters, so please excuse my lack of knowledge on the subject. I want to run the GRASS r.neighbors function on cells that meet a specific criteria, ...
0
votes
1answer
499 views

Why is the result of a raster calculation integer when it should be decimal?

I'm trying to calculate the NDVI using raster calculator, but the result is integer instead of decimal. NDVI = (NIR - RED)/(NIR + RED) The result is normally in the range -1 to 1, but when i tried ...
0
votes
1answer
36 views

Create elevation dependent mean values in ArcGIS RasterCalculator

I have two rasters. Raster1 is a reclassified raster for certain elevation value ranges. Raster2 is an elevation raster too but with gaps. I want to fill the gaps of Raster2 by the median of the ...
2
votes
1answer
181 views

Raster Calculator syntax

I have two rasters depicting climate in two periods and I want to compare their values. I want to create a third raster returning: Values of raster 1 are within the minimum and maximum values of ...
2
votes
1answer
36 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 ...
1
vote
1answer
546 views

ArcMap 10; Syntax for Minimum operator in raster calculator

I want to linear stretch my raster grid formate having column/rows 3128, 3503 with 30 meter resolution by using the following syntax in raster calculator of arcmap 10.1. ("raster" - ...
0
votes
1answer
328 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 ...
2
votes
0answers
322 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 ...
3
votes
2answers
120 views

How do I get rid of this thin band between raster layers created from TNM?

After hitting my head against the table for many days, I'm humbly presenting myself to the QGIS community. I downloaded 4 IMG files (1/3 arc second, elevation data) from The National Map on the USGS ...
1
vote
2answers
600 views

QGIS's raster calculator— running as a batch process?

I have a series of raster files (150 or so) that I need to multiply by a baseline raster. Unfortunately, the series of rasters have a different cell size (30m×30m i.e. .00027777778 degrees ...
3
votes
0answers
337 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 ...
1
vote
0answers
110 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 ...