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

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How to get hypsometric curve from elevation data?

I have my elevation data but cannot make an attribute table from it and so I'm not sure how to get any of that data into a table in order to make a hypsometric curve.
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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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438 views

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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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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How to make transparent the background of a topographic map in QGis 1.8.0?

I'm starting to use QGis 1.8.0. I have a raster topographic map, i.e. white background and black contour lines, houses, roads and so on. I want to make transparent the white background, so if I ...
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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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How to fully load a raster into a numpy array?

I have been trying to check my filters on DEM raster for pattern recognition and it is always resulting in missing last rows and columns(like..20). I have tried with PIL library, image load. Then with ...
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479 views

What Open Source (command line/API) method is there to orthorectify and georeference an aerial image given telemetry data?

How can I take an image and orthorectify it automatically with open source software? The information associated with each image is: camera specs latitude, longitude, elevation of the camera ...
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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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Is there a way to clip an image with the basic ArcView package (9.3)?

Is there a way to trim a geo-referenced air photo to an irregularly shaped boundary? I tried the clip tool shown in my attachment, but it didn't work. It looks as though the output extent field ...
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1answer
189 views

Raster to vector with gaps in Landsat ETM

I need to find size of water area from a raster (jpg) using QGIS 1.8.0-Lisboa. The raster is a Landsat image with gaps of data in it. I used Polygonize, but the output file shows wrong polygon size ...
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166 views

parallelization of raster mosaic

I would like to create a raster mosaic of the national USGS NED 30m DEM (~50 GB). I'd like to leverage parallel processing using python multiprocessing module where possible. I'm using ArcGIS 10.0. My ...
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285 views

How to cope with imprecision in floating-point grids?

I have a floating point grid/raster and will want to make all values rounded to the nearest tenth. I have converted to integer (added 0.5 for rounding), but the final floating point output grid is ...
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Grid vs TIF vs IMG

As the title suggests both of the above three formats are raster files. In ArcGIS, apparently there's no difference between them. So what's the difference between these three formats?
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How can I join several raster files using QGIS?

I'm new to QGIS. How can I combine multiple raster layers into one layer? The raster images are of different areas with very little overlap. The goal is to bring numerous town plats into one project. ...
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Extract Raster Value into Polygon Attribute

I have Raster Data for a State which has Elevation Data in its pixels. I also have Vector layer which has the 300 divisions of State. what I need is, I want to get the average elevation value of ...
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R: Download a large DEM, change projection, and adjust to smaller scale

This is a process that takes just a few seconds in GIS software. My attempt to do it in R uses a large amount of memory then fails. Is there something wrong in my code, or is this just something R ...
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643 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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926 views

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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How can I export raster data from Arcmap to an R *.grd file format?

I want to work with raster data in R, but I have problems exporting my raster dataset from ArcMap. By "export data"/GRID I get a file with an *.aux extension. What I need is *.grd. Can anybody help ...
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Breaking apart a polygon layer by unique values, creating many new layers

I have a large dataset of habitat information that I need to calculate distances from animal locations to the closest polygon of each habitat type. The way to do this, that I understand, would be to ...
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how to overlay shapefile and raster?

I have a shapefile with polygons. And I have a global raster file. I want to overlay the shapefile's polygons onto the raster grid and calculate the mean raster value for each polygon. How can I do ...
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188 views

What is the best raster format for large NoData areas?

Is there a good raster format for dealing with a large number of NoData cells? I do a lot of flood modeling and mapping, and recently I've been using rasters to show predicted flood depth and/or ...
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520 views

Raster to Vector

I want to map out moisture availability using satellite image but I do not know how to convert the raster image to a thematic map with limiting boundaries like state boundaries. I am using ArcGIS 9.3 ...
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4answers
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Advanced colour palette for raster data

I'm working with satellite date namely chlorophyll and sst. Each geophysical parameter generally has standard colours to represent them. I'm importing geotiffs into Qgis and I'm having difficulty ...
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879 views

grib2 to raster? (grib2 -> raster2pgsql -> PostGIS 2.0 -> GeoServer)

I'm looking to implement import of US National Weather Service data for doing various sorts of models (www.soils.wisc.edu/uwex_agwx if you're curious about what we're doing with the data). The ...
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1answer
171 views

How to speed up band math in R 'raster' package?

I have some GeoTiff rasters with over 100 bands in total, but they are not huge: resolution is about 1200x600 and total size is less than 7 mb. I'm trying to do a simple NDVI calculation: raster ...
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SPOT NDVI time series

I have 423 spot.vgt ndvi from first April 1998 till 31 Dec 2009. I want to know how to stack these NDVI to have one image for time series analysis? Or better to ask how is it possible to analyze a ...
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805 views

GDAL Clipping (hack)

I am trying to use the python script from http://www.sparkgeo.com/labs/2010/07/07/gdal-clipping-hack/ to clip a raster based on many shapefiles. The script is using a mysql database an i would like to ...
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What resampling technique should be used when projecting aerial photos?

I'm doing some time-intensive projecting of aerial photos, and I'm curious - what resampling technique is best to use on aerial photos? In ArcMap, my options are NEAREST, BILINEAR, CUBIC, and ...
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What is the correct way to convert a USGS Orthoimage from WorldImage format to tiled GeoTiff for GeoServer?

USGS provides different resolution orthoimage quadrangles in the WorldImage format (*.tif with an accompanying *.tfw world file). Some of these quadrangles can be used by GeoServer (2.1.0 - 2.1.2) by ...
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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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649 views

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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1answer
555 views

How can I change the class of one pixel in a classified image?

I have a classified image (I did it in ERDAS) with six categories. There are some misclassified pixels (especially high-density urban category). Is there any way that I can choose one pixel and then ...
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How to generate TFW files for a list of images?

I have a few digital images that are not georeferenced. E.g.: Img01.tif Img02.tif ... Img99.tif On the other hand, I have a text file, which contains georeferencing information for these ...
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1answer
271 views

ModelBuilder: How to extract data by date, export to separate tables and interpolate tables to rasters

I've been using ArcGIS for a couple years, but when it comes to model builder I've only worked with very simple models. I'm hoping someone that is much smarter than myself can help me in building a ...
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1answer
173 views

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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893 views

Creating a mask with transparent pixels in python

I have a geotiff image with pixel intensities ranging between certain values. Lets say bewteen -2 and 2 (the image is normalized). I have a certain threshold which interests me, lets sat 1. I would ...
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Create Zonal Grid in R

Suppose I have a n*n raster, and I want to create k square blocks (k can be divided exactly by n*n ) for zonal analysis: for example, when n = 4 and k = 4 a 4*4 raster is create with value 1 1 2 2 ...
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How to enclose clustered points with polygon?

I have a raster with forest (1), no forest (2) data. "1" is represent single/few trees and there is gaps between them. I want to create a polygon around these trees to a forest map. It is not a dense ...
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Using SearchCursor to access & export values in a raster table

I am desperately trying to export the values in a raster table to a .txt file. I've seen some other folk post about this, but for some reason can't get the code to work in my case. I have a raster, ...
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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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3answers
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Insert Raster to MXD using arcpy.mapping (ArcGIS 10)

What i want to do seems simple. But again i can't even find a workaround... I have got a lot of Raster-files (ESRI-GRID) which i need to insert into a layout mxd-file and then export the map to ...
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1answer
427 views

Python equivalent of gdalbuildvrt

Is there a way to perform the same task as the gdalbuildvrt utility using GDAL Python bindings? So far I have not found any way to do this other than creating a vrt of a single dataset and manually ...
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1answer
170 views

How to create cohesive Spatial Pixels from Spatial Points Dataset

I have a Spatial Point DF spo (covering an irregular shaped area of interest). The data are not on a regular grid due to crs transformation. My goal is a raster with predefined resolution and extent ...
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540 views

Spatial query of raster data

I have population distribution data as a raster layer and exposure contours as vector (polygon) layers. What I'd like to do is use the vector layer to estimate the population indicated from the raster ...
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In ArcGIS 9.3, how do I split a 3-band raster (.tiff) file and summarize the band values?

Using ArcGIS 9.3, I would like to make a new, single-band raster file that includes only one value: a summary of the three existing bands. The composite band is currently a composite .tiff file. ...
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QGIS Two Raster Data Sets with black line between the two sets where they join?

Where the two Digital Raster Quad sets (topo maps 7.5 Quad) overlap there is a significant thick black line (not a single line but wide and is wider the further south you go on the map). I am looking ...
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Export georeferenced image overlay from KML?

How might one export image(s) from image overlays in a KML file to a standard geo-referenced raster format like geotiff? Use case: NASA's Earth Observatory has a time series of the changing Athabasca ...
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How to clip raster image by the extent of each row in a shapefile with ArcGIS 9.3

I'm using Python to clip a raster image by each row in a shapefile with ArcGIS 9.3. I am hoping to end up with one raster image for each polygon row, clipped to the extent of the polygon row. ...