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

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2answers
215 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
617 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 ...
2
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1answer
35 views

Averaging large number of raster layers using ArcGIS for Desktop?

I have a large number of rasters (300+) I would like to average using Raster Calculator as is explained at How do I average a set of rasters? I know I can manually select each raster by double-...
5
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1answer
4k views

Averaging set of rasters using Raster Calculator of ArcGIS Desktop?

How do I average a set of rasters? I have remotely sensed chlorophyll a rasters for several days and I need to get an average of the days represented as one raster layer. I am using ArcMap 9.2.
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2answers
1k 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
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2answers
130 views

How to update raster pixel values based on another raster with conditions in QGIS?

I have 2 land cover rasters. I want to update parts of the first raster with values from the second using QGIS. The workflow should be like this: 1. Select values equal to 30 and 34 in the first ...
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1answer
270 views

I want to compare multiple raster layers against each other to identify changes in pixel values over time

I am using LAI values to assess vegetation growth over large areas. I want to be able to identify areas that are doing well and areas that are decreasing based on the changes in pixel values. Ideally ...
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2answers
347 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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1answer
48 views

Why does SAGA raster calculator interpolate between cell values?

I have a raster layer with a series of integer values (classes) for each cell. I am trying to use the SAGA Raster Calculator module (called through QGIS) with conditional statements to reclassify each ...
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1answer
65 views

QGIS raster calculator: difference gives NaN for Landsat 8 scene

I'm strugling with the QGIS Raster Calculator, trying to get a NDVI image from a Landsat 8 scene (path 222, row 84, date 2015-11-15). The problem is, I'm consistently getting NaN values for all the ...
4
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1answer
181 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 (i....
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1answer
31 views

Bands disappear after Raster Calculation ArcGIS [duplicate]

I have a tif file containing 36 bands. After I applied raster calculation on the file the bands aggregate into one single band which I don't want because I need them for further calculation. People ...
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2answers
324 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 ...
3
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1answer
888 views

How to use raster calculator in ModelBuilder to batch reclassify hundreds of rasters?

I'm attempting to use iterate by raster to feed all the files through a simple map algebra expression (I'm looking at data that indicates probability of salamander habitat) so I want to reclassify the ...
2
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1answer
27 views

GRASS 7 raster map calculator

I am new to GRASS and am trying to use it because I can't afford the Spatial Analyst extension in ArcGIS. I am trying to remove all of the values in a NDVI raster less than some value to exclude ...
0
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0answers
12 views

Cropping out overlapping raster areas from old maps?

I am trying to take out the white bordered areas from my crop lines from multiple PDF maps I georeferenced and now exist as rasters. My goal is to mosaic or merge them all together to have a seamless ...
2
votes
2answers
73 views

Raster calculator in Process Toolbox Qgis

I am not able to find the Raster Calculator in my process toolbox anymore, even though I worked with the Raster Calculator through the toolbox in the same version of QGIS (2.8) one month ago. It ...
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0answers
39 views

Getting values lower than specified using Con, Raster Calculator?

Expression used in raster calculator (ArcGIS 10.2.2 for Desktop): Con(("%NDVI.tif%"> (-0.05)) & ("%Height_2015.tif%" >= 16), "%Height_2015.tif%", 0) I want an output raster containing ...
3
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2answers
3k 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 ...
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5answers
130 views

Normalizing raster using raster calculator in ArcGIS 10.3.1?

I have been trying to 'range standardise' or normalise my raster values from 0-100 and I know how to do this mathematically: ("raster"-min("raster"))/(max("raster")-min("raster"))*100 and I have ...
6
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1answer
2k views

How to evaluate raster calculator expressions from the console?

How can I execute from the console an expression that should be used with the raster calculator? I'm searching for something like this: qgis.someRasterCalcClass.evaluate("boh@1 + boh@2", "outputfile....
3
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1answer
41 views

Using raster calculator to show multiples of particular value?

How do I use raster calculator so that the new raster only shows multiples of 128? I'm not sure what the expression should be.
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1answer
49 views

How to get the inverse of a raster in ArcMap 10.1

I have a raster ranging from 0 to 80,000. I want to invert this, such that 80000 becomes 0.0000125. When I use a raster calculator as (1/x) it returns 1s where the were values and blank where there ...
6
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2answers
104 views

How to calculate the difference between two rasters in QGIS?

I have two similar rasters of the Mount Vesuvius and surroundings: one spans 20 kilometers, and the other one 50 kilometers. The two rasters are overlapping: What I would like to do is to create a ...
6
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3answers
7k views

How to standardize raster output from 0 to 100 using raster algebra?

I am working on generating an integrated moisture index based on the following equation: IMI = (hill shade * 0.5) + (curvature * 0.15) + (flow accumulation * 0.35) Iverson et al. 1997 Another ...
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1answer
43 views

How can I calculate the percent of a raster cell covered by a polygon?

First, I am going to try and intersect a raster and a polygon shapefile. I'm not 100% sure how to do this (or if I need to do this for the next step), so if you have any suggestions please let me know!...
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1answer
328 views

Creating an R factor raster in RUSLE Soil Loss equation with multiple input rasters

I am attempting to obtain the rainfall erosivity "R" factor for the RUSLE Soil Loss equation using rainfall PRISM 30 year history data. I have both monthly and annual data that comes into ArcMap as ...
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1answer
33 views

con statement to change the default value in ArcGIS

I have obtained a flow accumulation map using Arc Hydro tools and obtained the default value in the range of 0-204567. Now I need to change these value by default so that it gives 1 instead of zero. I ...
3
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1answer
54 views

Summing pixel values from several raster layers with partial overlap in QGIS?

I have several presence maps (rasters values 1 and 0) from different species. They are all from South America, but they do not have the same extend (i.e., different sizes). So, I am trying to ...
3
votes
1answer
29 views

Problem with algebra formulas for work with gdal_calc.py

I'm trying to update some values of a raster based on another raster. 1st raster (A): landuse data (values from 10 to 240) 2nd raster (B): mask data (only nodata values and a given value, for ...
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1answer
141 views

How to reclassify raster data that falls within a polygon

Thansk for your response Okay so I will reword my question more clearly I'm currently using ArcGIS 10. My task is to map forest cover with the image classification tool. The problem is some of the ...
3
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1answer
43 views

unexpected output from raster calculator function

Working in ArcMap, I am trying to convert the logit values in raster into their actual probabilities (logistic regression,) using the following function: 1/(1+Exp(-"sn_topo_poly_log")) Ive used this ...
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0answers
20 views

problem with raster calculator syntax [closed]

I am trying to build a raster representing the output from a logistic regression model. i keep getting syntax errors. heres the script: -2.41-(15.97 * "Topographic_Predictors\wadem10m_annsolrad") - (...
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1answer
26 views

Iterate variables in Con statement in Raster Calculator- model builder

I have this formula which works fine in raster calculator on its own. Here is a simplified version of it: Con((("Trial_analysis\winter_pm" == 2)) & ("Wind_directions\winter_pm_WD" <=b) & (...
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2answers
47 views

Combining non-overlapping binary rasters with ArcGIS Raster Calculator?

The issues I keep seeing depend on unique combinations of values. I have three rocktype raster layers for area and they are edge-to-edge (they do not overlap). They each have "VALUE" fields and "...
1
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1answer
54 views

Constructing LS factor for RUSLE without outliers using ArcGIS for Desktop?

I'm using the following formula in RUSLE via raster calculator to obtain a LS factor Power(Flowacc)*1/22.1,.4)*Power(sin(slope)*.01745/.09,1.4)*1.4 My expected outcome is a raster from 0 to ...
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0answers
26 views

Curve Number equation

I have a floating point raster of Curve Numbers (70-91) and I'm attempting to use the curve number equation to create a weight raster for flow accumulation, to determine runoff for a single rainfall ...
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1answer
62 views

Raster calculator fails with large raster in QGIS

I'm working in QGIS 2.14.1 with a DEM ranging from 200 feet to 1600 feet elevation called "dem_3m_Zft1b" (geotiff, 16822 X 33349 cells, No-data =-9999) If I enter "dem_3m_Zft1b" > 0 in the ...
0
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1answer
118 views

QGIS raster calculator wrong output

I am trying to create a mask from a DEM (SRTM tile) using raster calculator in QGIS. I have performed the same operation in ver 2.6 with no problem but in the current version the output is incorrect. ...
1
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1answer
424 views

PostGIS ST_MapAlgebra Assistance

I would like to perform the equivalent of the below ArcGIS raster calculator equation in PostGIS using the ST_MapAlgebra function and return it as a tif using ST_AsTIFF. Con(("Sol_gain_clipped.tif" &...
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1answer
60 views

ArcMap raster calculator error 000539

Using ArcMap 10.3, I am trying to perform map algebra on a raster with 2013 annual PRISM precipitation for the U.S. (http://prism.oregonstate.edu/recent/). The raster has 1 band an is floating point. ...
3
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0answers
49 views

Mapping habitat suitability using ArcGIS for Desktop?

I have been having somewhat of an issue recently with one of my projections. I am currently trying to map out the preferable habitat for a species in Arcgis. To do this, I performed a GLMM in R and ...
1
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1answer
539 views

Raster Calculator error

I'm trying to use the Raster Calculator inside ModelBuilder to get rid of null values, but I'm hitting a snag. I'm using the expression: Con(IsNull("%temp_ras%"),FocalStatistics("%temp_ras%",...
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2answers
33 views

Recalculating raster based in number of cells?

I am working with binary rasters of fish species distributions (1=presence, 2=absence). I am looking to recalculate each raster in this way: Count the number of cells with value 1. Divide: 1/Number ...
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1answer
21 views

Why would having a reference string “boh@10” cause a crash?

When using the raster calculator in a pyqgis script, I have several layers to process. When it gets to "boh@10", the processCalculation() call crashes. I don't see anything in the code that requires ...
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0answers
39 views

Create Cost Surface Raster with slope as percentage of total costs

I know there is a similar question on this website (How to Create Cost Surface Raster for Least Cost Path Analysis?) , but I couldn't find the answer that I'm looking for. I'm currently working with ...
2
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1answer
64 views

Is QGIS Raster calculator faulty?

I am trying to perform some rounding operations on rasters. I have used GDAL to convert the raster to an integer which is fine but now I want to /100 which should be simple in raster calculator but ...
0
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2answers
94 views

Syntax Raster Calculator

I have never worked with the raster calculator before and I can't solve my problem. There are two raster datasets. One contains roads ( "closed", "in use", "under construction") and the other dataset ...
1
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1answer
105 views

Conditional statement in raster calculator - ArcMap

I'm Just wondering how to incorporate a conditional statement basically to say: if value in raster >= 128, then put in new raster, otherwise make the values null. Basically the purpose of this is ...
1
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2answers
94 views

Using Raster calculator in Modelbuilder ArcGis 10

I am using Modelbuilder to calculate several rasters with different parameters for each grid cell. One of the final steps is to calculate the log of one of the rasters using Raster calculator. ...