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

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8
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1answer
495 views

Calculating distance from points to different class in raster

I am looking for some advice on how to calculate the distance from a point to a different class of a raster. Specifically, I have observations (points) of animal use overlaid on land cover data. For ...
8
votes
1answer
1k views

How to make a new raster using con() script in Python?

I'm new to Python and have been trying to code a raster calculator style script. Basically, I want to convert a raster that has values 0 to -10,000 into a raster that is populated by 1s between ...
7
votes
2answers
94 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 ...
6
votes
3answers
1k views

30,000 data points… can this be reasonably served using openlayers?

I'm trying to tackle a web GIS problem and need to figure out the best strategy. I have a map with 30,000 cells on it forming a grid for the province of Alberta. I have a list of data points for ...
5
votes
2answers
632 views

How to calculate the number of cells with a given value?

I have a raster file where all cells have values between -3 and 7, no data value is -9999. Have can I calculate the number of cells with a specific value e.g. 6? Can I use the calculator?
5
votes
1answer
5k views

How to crop raster layer?

Can anyone tell me how to crop a raster layer in QGIS? I want to make contours from a section of a layer, and including the whole layer will create far more data than I need and slow down the ...
5
votes
1answer
160 views

Calc bottomline of valleys

Which way do I calculate bottomlines of valleys or even more preceise: which way do I "find" valleys (for example suggested tectonic faults). Sample below shows a height profile (profile from line) ...
5
votes
1answer
299 views

How to calculate a standard deviation across multiple raster layers?

I have 15 raster layers. Each one shows accumulated precipitation (rainfalls) for the month of April for the same US state during a given year. So, I cover the period from 1997 to 2012. I would like ...
5
votes
1answer
1k views

Working around the raster calculator in ModelBuilder - ArcGIS

I am experiencing a problem with the raster calculator in the Model Builder under ArcMap 10. I need to combine two layers: a drainage map (issued from a series of previous operations on a DEM) and a ...
5
votes
1answer
621 views

Raster processing with Python or Arc raster calculator

I have 4-band NAIP imagery that require the following processing steps: Convert to 8 bit unsigned B/W Reverse (note not inverse) the image, so that dark values appear light and light values appear ...
5
votes
2answers
2k views

Using individual bands from a multi-band image in ArcGIS 10 raster calculator

I'm trying to use individual bands from a multi-band TM image (IMG file) within the raster calculator in ArcGIS 10 (SP2/3). I can add individual bands to my MXD, but raster calculator will only use ...
5
votes
1answer
438 views

Copy and Paste symbology in Raster?

I am trying to figure it out how can I take a preserved color from a raster I already set up before and then apply the colormap to a new raster file? Here are the details of what occurred: Before ...
4
votes
2answers
289 views

Using Python and open source modules, how can I perform Raster Calculator functions?

I would like to perform mathematical functions similar to those you would use Raster Calculator for in ArcMap, however I'd like to do it in Python without using the Arcpy module. I have the osgeo ...
4
votes
2answers
2k 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 ...
4
votes
2answers
2k views

How to exclude outliers from raster using ArcGIS for Desktop?

I calculated terrain curvature from a DEM. The DEM I use is interpolated from point elevation data. Generally, the DEM seems to be good, but some artifacts from interpolation exist. Those artifacts ...
4
votes
1answer
934 views

How to reclassify in Rastercalc?

I now need to reclassify, I'm using rastercalc... but I can't get the syntax right!! I need that values >0 become 1 I found this example... eq( [relief]@1, [mask]@4, 150 ) so I tried: ( [raster A ...
4
votes
1answer
58 views

Raster Calculator making incorrect calculations in ArcGIS for Desktop?

I am trying to use raster calculator (ArcMap 10.2.2.3552) to apply a poisson generalized linear model to estimate species abundances based on elevation. The outputs don't make any sense to me, and I'm ...
4
votes
2answers
236 views

How do I generate a random raster (or probabilistic cellular automaton) in QGIS?

I'm trying to create something like a cellular automaton land cover change model using QGIS, in which cells randomly change land cover based on probabilities determined from various input rasters. ...
4
votes
3answers
414 views

query raster cell values by point

I have a binary raster (0s and 1s) that I need to query given a set of point coordinates. This is easy enough to do with gdal (gdallocationinfo), but where it get's complicated is that I also need to ...
4
votes
2answers
115 views

How to do raster conditional comparisons in .NET?

I am comparing a raster with a constant value by raster calculator. Now I want to do this in a c# code. Question Is there any process to do this kind of raster conditional comparison in .net?
4
votes
2answers
146 views

How to find buffer radius around raster cell that covers a defined sum of raster cells?

I want to do a neigbourhood analysis on some raster data. I need to know how big a circle around each raster cell must be to include a certain amount of specified raster cells. Let's say that for ...
4
votes
1answer
165 views

How to create Series of Rasters that displays Standard Deviation from Mean?

Cell statistics question for you. I have 100 rasters of raw rainfall data in which the pixels each represent rainfall for that particular pixel on the landscape for a single year during the 100 year ...
4
votes
1answer
67 views

Raster Calculator Bug at start

I use ArcGIS 10.1 on a Windows XP. ArcGIS completely shuts down when I attempt to launch the "Raster Calculator" tool. Has this happened to someone else? Any ideas on how to solve this annoying issue? ...
4
votes
0answers
45 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
1answer
723 views

How to reduce all value above certain value using Raster Calculator?

I have a raster with elevations above 2000m that I want to "cut" to 1800m. I cannot quite figure out the correct string and most simple way to do this in the ArcGIS 9.3 raster calculator. I tried ...
3
votes
2answers
759 views

Normalize raster values to 0-255

I need to normalize the values attained from a band ratio to 0-255. I'm using QGIS. How do I do this? Any ideas?
3
votes
1answer
575 views

How to reclassify raster inside polygon mask, leaving values outside as they are?

I am in the final stages of a landcover classification and need to reclassify thematic raster values that are inside different polygon masks, while leaving the values outside as they are. Can I do ...
3
votes
1answer
123 views

Where is qgis getting the NO DATA value from?

I have a project that contains an 8-bit paletted layer (call it the mask layer) and a float 32 single band layer (call this the clip layer). I create a new raster by using the raster calculator, ...
3
votes
1answer
527 views

Why does Raster Calculator (RasterCalculator_sa) give ERROR 000539 in ArcPy?

I am getting a not executed error for a raster calculator. Here is part of the output: File "C:\projectTemp\FloodAnalysis\floodxsectionanalysis.py", line 107, in makeSeemless ...
3
votes
1answer
418 views

How to exclude some parts of raster classes based on size of area?

I have a raster file with 5 classifications. I've calculated area for all of the classes via Zonal geometry, Arcmap 10. Now, I want to exclude patches which are smaller than 100 sq. km. and ...
3
votes
1answer
351 views

How to enter formula into ArcGIS Raster Calculator?

i have the following formula: L = (l/22,1)^m (l = Flow length) m is calculated like this: m = 0,5 when slope is >4 degrees m = 1,2 * sin^1/3a when slope is <4 degrees (a = slope in ...
3
votes
1answer
273 views

how can I obtain the areas where my rasters overlap, using Qgis?

I have a bunch of raster files showing the distribution of different species of mammals, and I would like to obtain the areas where they overlap, the areas in whitch more than one species can be found ...
3
votes
2answers
49 views

How to calculate the a list of rasters?

I'm writing ArcPy code in ArcGIS trying to calculate a list of rasters. I get an error message that says: TypeError: unsupported operand type(s) for -: 'unicode' and 'unicode'. Here's my ...
3
votes
1answer
87 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 ...
3
votes
1answer
84 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
votes
1answer
143 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 ...
3
votes
1answer
30 views

Fast editing in raster calculator — adding lots of images together

I need to add pictures together to make one raster. In one session there are about 150 - 200 images (named randomly - see syntax example) There are about 50 sessions (named randomly) Is there any ...
3
votes
2answers
81 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 ...
3
votes
1answer
81 views

Cell values to No data

I need to set cell values in one raster to NoData based on another raster. Both rasters have the same extent and some cells overlap. For those cells that overlap I want to set them to NoData in ...
3
votes
2answers
470 views

Scale raster in ArcGIS using raster calculator

I have a raster with values ranging from 0 to 8991130624. This raster is actually the result of a cost distance analysis. I want to scale the raster to range from 0 to 1 and take the inverse? so ...
3
votes
1answer
139 views

Issue with Sextante r.map calculator and modeler

I am trying to build a model with Sextante modeler and the r.mapcalculator algorithm but when I run the model I get the error message: ‘Could not load layer: ‘….’Check sextant log to look for errors ...
3
votes
0answers
29 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
1answer
183 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 ...
3
votes
0answers
79 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 ...
3
votes
1answer
103 views

Stack sat images and run operation on all

I have about 300 MODIS satellite with different acqusition dates, covering the same area. I am not used to work with so many tiles at once so I ask for advice. I am working with ArcMap10.1 What I ...
3
votes
1answer
283 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
2answers
309 views

Is it possible to attain a classified raster with several classes in just one QGIS raster calculator operation?

I'm using qgis' raster calculator and wanted to make a new raster (oraster) from the values of an input raster (iraster). something like: if iraster>2 then oraster=1; if iraster >4 then oraster=2; ...
2
votes
1answer
59 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 ...
2
votes
1answer
152 views

Combining Geological Grids

I have a situation where I have 3 Geological grids, each showing a different horizon + the Seabed Grid. I need to extrude between these grids in order to make the 3D polygon for the geological ...
2
votes
2answers
917 views

query raster in ArcGIS 10

I am using ArcGIS 10 (includes spatial and geostatistical analyst). I have a raster (GRID) with a value range of -167 to 18. I would like to query the raster and create a new one with only the values ...