Questions tagged [raster-calculator]

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

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10 views

Giving input of multiple rasters in Raster Calculator of ArcGIS Desktop

I want to add-up more than 100 raster datasets to derive the sum of all. Adding all these one by one in calculator using basic algebra expression is time consuming. Can anybody suggest me how can I ...
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How to use mean function in QGIS

I want to make a raster showing the average values of 12 rasters. I use Raster Calculator and simply add all of them and divide them by 12 but the result is not correct! The max is far less than what ...
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Getting latitude / longitude in the QGIS Raster Calculator

I have raster files in the good and old EPSG:4326 (WGS-84) and I would like to create two other raster files with the exact same extent and resolution of it, but with the first raster having the the ...
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23 views

Constraining raster calculator results

This is in ArcGIS Pro. I will be performing a raster calculation to determine how much a given raster might change over time by multiplying the current raster by the percent projected change and then ...
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I want to create NDVI of multiple raster using ArcPy

I have multiple raster data which are layer stack. Now I want to create NDVI of each raster data. I am stuck in the code, I developed a script but dose not generate any output. import arcpy, os from ...
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30 views

QGIS Raster calculator predefined expressions syntax?

What is the correct syntax for the 'Predefined expressions' feature of the Raster Calculator of QGIS 3.14? How one can replace layer names with variables in the expression being saved (so they can be ...
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1answer
35 views

Is it possible to do raster calculations with ST_Union (PostGIS)?

I would like to perform raster calculations in PostGIS. (A change detection should be performed, for this purpose every pixel of different raster is accessed and it is checked if the pixel values have ...
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12 views

Kernel Density Percentage Isopleth

I have generated Kernel Density Rasters from GPS species locations. I want to generate percentage isopleth polygons to enable me to identify core areas. I am using ArcMap10.6 and therefore cannot use ...
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1answer
36 views

GDAL raster calculator

I have a series of raster data (GeoTIFF) with 5 bands (B / G / R / rededge / NIR). I would like to calculate different indices by using the gdal raster calculator. I would like to use the batch ...
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How can I calculate the interquartile range of a group of overlaying pixels using the raster calculator function in R?

I am able to find the mean, min, and max, but I can't get the interquartile range when I replace mean with "iqr" for instance. This works: list <- list.files(path="C:\\Users\\Desktop\...
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1answer
19 views

Intersecting multiple classified rasters

I have 3 raster files: A transform aspect (TRASP) layer (classified into 2 strata-(0-0.5, 0.5-1)) A canopy cover layer (classified into quantiles-5 breaks) A canopy height layer(classified into ...
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40 views

How to calculate mean of raster layers where some layers have missing values (R or QGIS)?

I am trying to create annual averages of some raster layers, but some of these layers have gaps in the data. If all pixels in all of the layers contained info I would just use Raster Calculator and do ...
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Issues calculating VARI from Sentinel L2A

I have a dataset of Sentinel-2 L2A imagery for which I am calculating the Visual Atmospheric Resistant Index (VARI). The bands that I am using (B2 = blue B3 = green B4 = Red) I am working in ArcMap. ...
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58 views

If conditional for multiple raster in ArcMap10.6

I have a list of four rasters and i want to apply a lot of if then statements using Python in ArcMap 10.6. I was able get the result using raster calculator with Con statements and i tried to use the ...
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How to train or calibrate stream flow accumulation using observation data?

I need to calculate flowrate at designated coordinates (Point of interest - POI) in a watershed. I have real-world data from stream gauge stations along this watershed for each 50-150 km2 rainfall ...
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Constructing CON statement in Raster Calculator of ArcGIS Spatial Analyst

I have this expression that works in the QGIS Raster Calculator but not ArcGIS Raster Calculator. How can I reconstruct it? It is a binary raster that I am working with. ("Outputs\Model Fin" ...
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How to use a clipped Raster with Raster Calculator in a script

I want to make a script which will asking me a raster layer, a vector layer and a double. The point is to clip the raster and then process to filter data, like (raster > filter)*raster. My script ...
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How to write natural logarithm in SNAP software

I want to compute the temperature of a band using the equation: where L(6) is Band 6 of a Raster file and K1 and K2 are constant. I am using Band Math to perform conversions. However I could not find ...
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Analyzing NDVI rasters with same dimensions but different extents with Raster Calculator

I have drone sourced remote sensing imagery (NDVI) of a trial site set up to measure yield response to varying nitrogen (N) rates. The trial includes N rates ranging from 0 to 600 kg/ha. The trial ...
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1answer
26 views

Calculating average of values in raster in QGIS?

I want to get the average of values in a raster. How do I get this using Raster Calculator? I was looking for this kind of function: AVE("yourraster@1") in the raster calculator.
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1answer
39 views

NDVI calculation

I am a newbie in PyQGIS. I start to write my own simple code to automatically calculate NDVI from Landsat 5. Here is my code: from PyQt5.QtGui import * from qgis.analysis import * land_3 = 'D:\...
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54 views

Understanding what the Min/Max commands in QGIS raster calculator do?

I understand the examples on the official QGIS page showing bracketed expressions result in 0 or 1 and those integers can be scaled or values added, but I clearly do not understand how to use the MIN ...
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60 views

Identifying and quantifying gullies and hags from aerial imagery in QGIS

We are involved in an extensive peatland restoration project in the Shetland Islands. We provide high resolution and accurate digital surface models and orthomosaics for initial analysis and on-going ...
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1answer
34 views

QGIS raster calculator splitting resulting image in two

I'm trying to calculate vegetation indices via the QGIS raster calculator using two separate bands of a Sentinel-2 tile (both of which have the same extent and CRS) but the resulting image is split in ...
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1answer
30 views

How to assign fixed values in a raster using to multiple polygons in QGIS?

I have digitised multiple small polygons over a city boundary and its floodplain. I would like to create a raster of the run-off coefficient out of it (for a flood model). Therefore I would like to ...
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Selecting pixels from a raster by value

I have two digital elevation model rasters. I calculated the difference of these two rasters using raster calculator and got a single output raster. Now I want to highlight areas where the surface has ...
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1answer
22 views

QGIS Rastercalculator: unexpected results for cos() function

I've calculated the slope values of a DEM and created a raster with values from 0 to 51,3 (degree). I wanted to calculate the Cos of these pixel values with the Raster calculator (to calculate in the ...
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1answer
31 views

Multiple linear regression between grids: reviewing the assumptions

I am performing a regression analysis with three raster stacks in R. This worked so far. Now I want to check the conditions of the model and I am not sure how exactly that should work in this case. ...
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19 views

Calculating TWI after getting the flow direction, flow accumulation and slope

There are many tutorials online with this, but it seems that people use different equations and/or what they put into the general ln(a/(tanb)) equation. Do I need to know the cell size of the raster ...
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1answer
39 views

Empty result layer was created by raster calculator

I'm a new user of QGIS and learning some tips from this book https://www.amazon.com.au/Learn-QGIS-Andrew-Cutts/dp/1788997425. I'm currently practising how to use raster calculator to find areas at ...
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1answer
68 views

Function to sum by pixel order in R

I am trying to quantify the number of months required to reach a specific value at the grid level. For this, the monthly raster values were then ranked, and the time length was defined as the number ...
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Vegetation coverage using NDVI

I met a problem when I was using this equation f=(NDVI-NDVI MIN)/(NDVI MAX-NDVI MIN) to get vegetation cover. The problem is “NDVI-NDVI MIN” part. NDVI value range is (-0.05115,0.605945)When I used ...
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1answer
17 views

TypeError: ufunc 'expi' not supported for input type, and input can't be safely coerced to supported type according to casting rule ''safe''

Here is my code for raster calculation in ArcGIS. However, I am getting raster file for "uw" only. The python is unable to calculate exponential integral of raster uw. Thus, I am not getting the ...
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25 views

How to write Con expression in Raster Calculator

I want to calculate S factor for USLE model when I tried to run my expression, I met a problem. Con("Slope_Fill_sl" <=5 ,10.8*Sin("Slope_Fill_sl" +0.03 ) Can anyone tell me which part I did wrong?...
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Raster Calculator functions

I was trying to overlay 8 thematic maps using the raster calcular in modelbuilder in ArcGis Pro but the ouput displays using only the sketch symbology (one symbol) when I wanted the classify. I was ...
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Building a model to standardize rasters in QGIS

I have a little problem, but I think there is a simple solution, but I can't see it. I want to make a simple model for the rasters to standardize them using a simple formula: I want to compare the ...
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How to get a conditional attribute from two Raster datasets attribute table?

I have two rasters, clipped both the dataset using the same shapefile, project them to the same coordinate system but they have different cell size and different extent. The rasters are of the ...
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2answers
47 views

Round Raster values up to nearest 10 QGIS

I have a raster with cell data varying between 0.1 and 156. I want to round the data to the nearest 10, i.e any value between 0.1-10 = 10, 10.1-20 = 20 and so on. Theres lots online about rounding to ...
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Issue with QGIS modeler raster calculator

I'm trying to apply a formula to scale an NDVI map from a WMS with QGIS modeler, but it keeps throwing me an error. I tried to do this without the modeler and it works. Here are the steps I want to ...
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50 views

QGIS Raster subtraction giving 0.005 value off from correct value

I have two synthetic DEMs I have created to test a method of detecting changes. I am using the Raster Calculator to subtract the first DEM from the second DEM. The formula is simple, just "...
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1answer
28 views

How to write it on ArcGIS Raster Calculator?

I just started using the Raster Calculator, so I don't know how to build the formulas. How can I do this? I need to write both of these formulas: D = is a raster file called "Slope_2" P = 13
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Input type error from raster calculation in ArcPy

I am trying to do raster calculation in ArcPy, which includes the application of expi (exponential integral function). Here is my code : import arcpy import scipy.special as sp from scipy.special ...
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1answer
44 views

QGIS raster calculator using second raster to set value in first

I have two rasters. ras1@1 has values from 1-50, ras2@1 has values 0 and 1. I want to convert values from ras1@1 >= 4 to 1, except where ras2@1 = 1, which I want to set to 0. I cannot work out how ...
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13 views

ArcGIS for Desktop: Interpolate point to raster for polygons separately

I have the point feature file MyPoints.shp with the field thickness and the polygon feature file MyPolygons.shp. My attempt is to calculate a raster from field thickness of the points in MyPoints.shp ...
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42 views

Raster Calculator conditions in QGIS [duplicate]

I'm trying to create an index using the Sentinel Imagens at Raster Calculater (QGIS), but I don't know how to put the following conditions: if ((B2>B3) and (B3<B4) and (B4>B11) and (B4>...
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1answer
63 views

Dealing with no-data values in raster calculator of QGIS

I am trying to patch two rasters with raster calculator but I am not finding the way to work with no-data values. Lager@1 has some information I need as first option, this has as no-data -9999 (...
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21 views

QGIS Raster Calculator with Python

I was wondering if you could help me with my problem. I want to execute a Map Algebra expression with the QGIS Raster Calculator. It would be easier to use the GDAL Raster Calculator, but since the ...
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29 views

Using exponential integral function for raster calculation in ArcPy

How do I use "exponential integral" function for raster calculation in ArcPy? The equation that I want to apply in raster calculator is of the form EXPINT (r^2*S/(4*T*t)). Here, r, S, and t are ...
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1answer
27 views

Find overlapping area of each class in classified images

I have three classified satellite images, lets say 2005, 2010, and 2015. All images are similar i.e. the same total area and same number of classes. I want to output those areas where pixels of all ...
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28 views

Normalizing raster reflectance values between 0 and 1 in ArcGIS Pro 2.4.2?

I am using ArcGIS Pro, and I am trying to mine some data from a raster that I collected via UAV (drone) imagery. The multispectral sensor I used consists of 5 different spectral bands, and radiometric ...

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