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

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8
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1answer
445 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
913 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 ...
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
515 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
4k 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
158 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
272 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
574 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
395 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
234 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
1answer
818 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
3answers
380 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
110 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
132 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
66 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? ...
3
votes
1answer
564 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
670 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
2answers
186 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. ...
3
votes
1answer
422 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
101 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
369 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
384 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
299 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
257 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
1answer
89 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
134 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 ...
3
votes
1answer
78 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
436 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
134 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
1answer
92 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
0answers
71 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
263 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
290 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
49 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
132 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
855 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 ...
2
votes
1answer
97 views

extend the size (area) of raster

My problem is that I would like to multiply two rasters using raster calculation tool. Both rasters have values 0 and 1, but the covered area of first raster is bigger (100 x 100 miles) then the area ...
2
votes
1answer
70 views

How could I assign point values to a raster stream segment?

I need to assign a point value in raster format to a raster stream segment, which contains the point. See bellow: The expected result is a segment, whose value is the point value. How could I?
2
votes
1answer
109 views

How to iterate GRASS region definition?

I am using GRASS r.skyview command (v.7, Windows) to determine "urban canyon effect" on pollution due to the presence of buildings. The command nicely works, unfortunately I need to process a very ...
2
votes
2answers
53 views

Calculating loss of value from a wind turbine on surrounding properties depending on distance

I have to evaluate where installing a turbine would be most efficient, depending on wind speed and price of properties surrounding each cell in a raster. The cost on value of properties is computed ...
2
votes
1answer
210 views

How to reclassify a raster (tiff) with multiple bands?

i have a raster file containing information about the windspeed average for the year. My purpose is to reclassify the 15 classes based on their rgb-composite. The color is the only information given. ...
2
votes
1answer
110 views

Measuring polyline lengths running through a raster - is this possible?

I have a reclassified raster layer with 4 values and a vector layer of polylines. I would like to discover the length of the lines running through each raster value, or the percentage of the lines ...
2
votes
1answer
137 views

Efficiently check for equal adjacent values in raster calculator

I have a raster consisting of integer values in each cell. I want to check every adjacent cell in a 3x3 grid to see if any one of the adjacent cells has a value EQUAL to the center cell, and if so, ...
2
votes
2answers
102 views

How to adjust raster size for usage in raster calculator?

I want to make a visibility analysis of planned wind turbines in my region. I have a DEM raster and a polygon describing the possible area where the wind turbines might be set up. People are ...
2
votes
2answers
394 views

Why does Raster Calculator return GRID ERROR-Unable to open the input grid: 1+FLOATC:\document…?

I'm calculating Simple Ratio (SR) from NDVI using Raster calculator in Arcgis. Here is expression I wrote in Raster calculator. SR=(1+float[NDVI_apr.tif])/(1-float[NDVI_apr.tif]) But when I evaluate ...
2
votes
2answers
704 views

How to calculate a new raster based on nodata values from original raster, in QGIS?

I'm using the raster calculator from core in QGIS and I need to generate a new tif raster file (mask) from the nodata values of another tif raster file. I tried isnull(), but no luck. Any one can ...
2
votes
1answer
65 views

Raster calculator help needed

I have time-series data (rasters) from which I need to calculate the direction of change (increase, no change or decrease) for every pixel from one time-step to the next. I further need an output ...