Raster is a data format consisting of regular grids of values, usually stored in an image-like format.

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Using polygons to apply unique value to all raster cells within those polygons?

In ArcGIS 9.3, I have a raster file that I would like to "mask" with polygons, giving a single value to all the raster cells that overlap the polygons. How can I do this? Here's a screen shot, ...
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Creating randomly shaped clumps of cells in a raster from seeds of 1 cell/pixel?

As my title says, I wish to "grow" clumps of cells from seeds within a raster. My base raster is full of 1's and 0's, 1's indicate land and 0's sea/NA areas. From the 1's I wish to select 60 random ...
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How to reclassify a very large land cover dataset?

Consider the NLCD2001 Land Cover dataset for Alaska (download link). I need to reclassify this dataset so that only pixels of value 41, 42, and 43 are preserved; all other pixel values should become ...
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How to reproject a raster file in QGIS with datum transformation?

I want to reproject a tiff raster file from projection A (ETRS89/UTM Zone 32) to projection B (DHDN/Gauss-Kruger zone 2). The two projections have a different datum so I have to use a datum ...
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seeking “Available Sky” implementations

I'm looking for implementations of an algorithm called "Available Sky". ArcGIS (Spatial Analyst or GRID) is preferred, but solutions in GDAL, SAGA GIS or others are perfectly acceptable. The ...
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Make the nodata area of a resampled orthophoto overview white?

I have a set of orthophoto images which are each fully filled with data, but when placed together the coverage does not form a rectangle so there are nodata areas. In MapGuide, I need to be able to ...
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Is there a fast way to copy large raster datasets between File Geodatabases?

Why does it take so long to copy a large raster dataset from one file geodatabase to another? I can copy the entire database in windows explorer in minutes but copying a single raster in ArcCatalog ...
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Extract the area of a DEM above where 60% of the region lies?

I have a DEM of a mountainous region. I'd like to extract the areas of the DEM above which 60% of the total DEM area lies. So, essentially I'd like to extract the areas representing upper portions of ...
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Best way to manage large number of geoTiff rasters

I have around 2-3000 1-bit geoTiffs of size 11000x9400. Color 0 should be transparent, and QGis gets it wrong in the first place, so I used a .vrt file to set all the parameters in one single place. ...
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869 views

How to apply a Majority filter in GRASS GIS?

I was wondering if someone could help me write a majority filter for GRASS GIS. I have this map (see below) which I need to run a filter over to make the red areas a bit more dominant. I know I can ...
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How to convert a vector boundary to a raster map?

I need to output a PNG file of a raster map overlayed with boundaries present in a vector map. The problem is, the r.out.png script only exports a raster map. My boundaries are in a vector format. ...
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Looking for a fast, open-source raster cost-distance function to use in code

I've been scouring the internet for a fast, open-source cost-distance function that I can embed inside my code. The functionality should basically work like the ArcGIS implementation where I can ...
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706 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 ...
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How to add a band to an existing GeoTiff using GDAL?

This seems like it should be straightforward but I can't for the life of me figure it out. Given an existing GeoTiff containing a single band, how can you add another band to that GeoTiff? Is the ...
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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 ...
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GDAL RasterizeLayer Doesn't Burn All Polygons to Raster

I am trying to burn a shapefile to a raster using GDAL's RasterizeLayer. I pre-create an area of interest raster from a different shapefile, given a specific pixel size. This AOI then serves as a base ...
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Smoothing raster features into polygon

I have raster data representing urbanized areas, which I'd like to trace and convert to a polygon. Using ArcMap's Raster to Polygon tool, I'm able to get something close to that. Unsimplified: ...
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calculate area of vegetations in a raster file

How do I calculate area of several vegetation types in a raster (.img file type) image. They are color coded. Am using QGIS (1.8.0) and ERDAS 9.2.
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Identify corrupt shapefiles or rasters via Python or ArcObjects

I'm interested in a way to identify rasters (e.g., ESRI GRID format) or shapefiles that are corrupt that would prevent them from being used in an analysis tool. I have a large number in structured ...
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R, rasterVis and RGL: how to prevent reflective surfaces?

I have been experimenting with digital terrain model files in ESRI ASCII grid raster format. Despite zero experience with this type of data I found it very easy to load into R, as per code below. The ...
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How to grid unevenly sampled categorical data?

I am looking for a method for gridding categorical data. I have extracted from nautical charts and field sheets a collection of points specifying the nature of the surface of the bottom of the ocean. ...
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Where is this raster offset being introduced in the QGIS processing toolbox?

I'm using the (awesome!) processing toolbox in QGIS 2.0 to reclassify some NoData values in a raster from -9999 to 0, but at some point in the process there's an offset of about 0.2 degrees being ...
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How to build an artificial 'dam' across a river?

I have a DEM. Created all files related to watershed including accumulation, direction, streams etc... I'm stuck creating a dam. I request you to please let me know how to build an artificial 'dam' ...
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How do I layer stack rasters in QGIS?

I have some multi-spectral data, where the individual bands are separate Raster files. How do I layer stack these rasters so that I get one raster with 3 bands instead of 3 different rasters? This ...
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How to change null values raster values to 0 in QGIS?

I need help... I'm having problems with QGIS. I have some rasters that appear to have null values, even though I reclassified them to obtain a boolean raster :( How can I change the NULL values to 0?
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Find the intersection of two rasters

I have two raster images, Boolean classified (1 or 2). They overlap in given areas. I need a raster that is only the overlapping sections. Using Arcinfo 10. Answer can only use raster methods, no ...
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How to add Raster legends in QGIS map composer?

Is there a plugin or method to add legends for raster layers (with a custom colourmap) as an item in the print composer?
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Simple Question: Raster from ArcGIS to Geoserver

we have a couple raster files which could be open in ArcGIS. They come with the extension of .aux and .rrd and they are the GRID file format from ESRI. We want to put them on Geoserver to overlay them ...
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Merging hundreds of Aerial Photos into one big file?

I have tried to merge my 405 Aerial Photos into one. I have FME and ArcInfo 10.0 at my disposal on Windows 7 64bit. I have tried the following: create a mosaic; export all images from a ...
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GDAL and Python: How to get coordinates for all cells having a specific value?

I've got an Arc/Info Binary Grid---specifically, an ArcGIS flow accumulation raster---and I'd like to identify all cells having a specific value (or in a range of values). Ultimately, I'd like a ...
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Statistical relationships between rasters

I am trying to analyze how sets of rasters relate to each other using some statistical techniques. As, I don't have much experience using the spatial statistics tools in ArcGIS I was exporting my ...
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Extracting roads out of Landsat raster images

For a study into the expansion of road networks in the rainforest I am trying to extract roads out of Landsat images. We already have sharp and cloud-free composites on which the roads are clearly ...
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Creating raster or vector raster from DEM point file?

i have a point shape of 75.000 elevation points in a regular 5 m grid. We now want to create a polygon grid with the elevation points as "centroids". Unfortunately, all attempts to do so fail: I ...
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How to install “1-band color raster color table”?

I would like to use the "1-band raster colour table" extension. I'm using QGIS Wroclaw 1.7.4. In the plugin installer I can't find this extension, even I quote for third party extensions thing. Does ...
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Finding specific pixel values ​​in ArcGIS using Python

I have a raster file containing some integer values. I need to find all pixels whose values are not defined in list like this one: l = [1,2,4,8,16,32,64,128]. Is there any easy way to solve that ...
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Best Way to Handle Many Raster Files in QGIS?

I have a project with a large number of raster files, but it is becoming very slow. I wonder which is the best way to handle all this. I'm simply georeferencing these files creating .wld file (geoTiff ...
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How to create a solar intensity map for a garden plot?

I'm interested in creating a raster surface that depicts the average solar intensity per unit area for a small garden plot. I imagine the inputs into the model would be the following: Plot ...
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Converting a polygon into a raster using R

I'm trying to convert a shapefile into a raster within R. My approach is to read in the raster as follows: library(rgdal) # Loads SP package by default demo <- readOGR('F:/data/', 'shapefile') # ...
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QGIS and Raster Mapping in 'Seamless' layer

I would like to use Ordnance Survey base mapping in QGIS. I would like to set up something like a seamless table in MapInfo. I think that the equivalent in QGIS is a Virtual Raster Table. The files ...
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Modify raster layer display and symbology properties programmatically with arcpy or ArcObjects

I have over 1500 NITF files that I need to be able to modify the layer display and symbology of programmatically from within ArcMap. I need to set the properties outlined in red below: I've looked ...
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R - How to sampleRandom() from large raster without NA values

I have a number of vary large rasters which need to be randomly sampled with the return value being a matrix of x, y, and value. The raster package sampleRandom(raster,n, na.rm=TRUE, xy=TRUE) will do ...
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How to compare areas in scanned historical land use maps

I am a relative beginner to using GIS, and am running QGIS 2.0.1 in Linux. I have two historical maps which I want to analyze, that show land use patterns in the same area at two different moments in ...
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How to keep spatial reference using arcpy.RasterToNumPyArray?

I am using ArcGIS 10.1, and want to create a new raster based on two preexisting rasters. The RasterToNumPyArray has a good example which I want to adapt. import arcpy import numpy myArray = ...
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478 views

Reduce extent of raster processing

I need to reduce the processing extent of my raster by some sort of automatic procedure in python. Currently the borders of the dataset I've been using has anomalies (due to the classification of the ...
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How to animate raster time series using open-source GIS?

I have a bunch of rasters taken about 10 minutes apart, and I have a nice QGIS project that produces pretty enough maps of them. I'm wondering if there's a way to animate this raster series, with a ...
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GRASS - Will r.to.vect work on this scanned map?

Total GRASS noob here. I have several very large hand contoured maps to digitize, and this thread intrigues me. In the past I have spent hours upon hours digitizing these maps and revisions in ArcMap. ...
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How to create points around edge of viewshed results?

Is there a tool or module, or multiple tools, in ArcGIS that will allow you to automate the creation of points around the outer edges of a viewshed? What I am trying to do is gather data about the ...
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ArcMap 10 - Extract raster cells from imagery based on RGB value

I've got some aerial photography (format: IMAGINE Image) which is detailed enough to see to fire hydrants and a shapefile of fire hydrants which was digitized based on some CAD data. My project is to ...
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Are there GIS tools for simulating landscape fragmentation?

I am currently looking for any GIS packages (or add-ons) that allow the simulation of landscape fragmentation on raster data. Maybe also other software than GIS tools? Does anyone of you have had ...
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What are the rules that the Gdal rasterize function follows to allocate a value to a cell?

How does the rasterize tool decide which value to represent when a cell covers an area which inclueds different values? I need it in this case for polygons but would like to know for lines and points ...