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

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Raster display for topographic map

I'm trying to see how good a custom topographic map could be using only free data For the moment I'm just playing with the data so of course the colours are not pretty. I did some classification and ...
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1answer
237 views

Setting projection to a geotiff file when it's shown as Unknown

I have a geotiff file that has no CRS in the metadata but I know that the CRS of the raster is WGS 84 UTM 22 N. How can I modify the geotiff file to have the CRS WGS 84 UTM 22 N in the metadata. ...
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74 views

Create 6 band IMG file with GDAL out of two JPG files, one with WorldFile coordinates

I have two JPG files 1 ortomap: http://imageshack.us/photo/my-images/703/ortofoto1.jpg/ with WorldFile: 0.683772574816354 0.000000000000000 0.000000000000000 -0.683739485024190 ...
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1answer
417 views

Georeference Raster File with WorldFile into an aerial photo using GDAL [duplicate]

Possible Duplicate: How can I transform a georeferenced JPG to a georeferenced TIF? UPDATE:Corrected link I must note that I am new to GIS so pleas be understanding. PROBLEM: I have a ...
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1answer
651 views

How to view a 155 MB raster stored in PostGIS?

I am using the following command to load a raster into a postgres database: raster2pgsql -I -C -e -Y -F -s 3086 -I -C -M myraster.tif myraster -F -t 30x30 | psql -U postgres -d database -h localhost ...
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1answer
202 views

Probability distribution from list of rasters

I have 100s (exactly 224) of wind distribution rasters. I want to create a probability distribution raster of wind speed using all these rasters, so we can predict the possible wind speed in any ...
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3answers
2k views

How to display row and column indexes for an image in ArcGIS?

I have been struggling with how to find the row number and column number for particular points in any raster map. My raster details: columns and rows: 720 360 cell size (0.5, 0.5) How can I ...
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2answers
479 views

Is there a way to load a kml raster super-overlay in QGIS?

I have created a set of tiled rasters as a super-overlay in Google Earth, and it performs remarkably well. Is there some way to load a super-overlay as a layer in QGIS? I am wondering if this could be ...
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3answers
378 views

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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1answer
220 views

PostGIS raster support

I have the following requirements to manage raster data 1) Convert raster-maps from BSB format to PNG or GeoTIFF 2) Cut the borders of the map 3) Merge individual maps to form a contiguous coverage ...
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891 views

Raster grid for zonal statistics in R

I have two raster layer, the first one r is my zonal mask as a raster grid, and I created as: ext <-extent(Yraster) r <- raster(nrows=32,ncols=32,ext) r[] <-(1:ncell(r)) and project it ...
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1answer
232 views

How extract data from SNODAS file?

I'm trying to extract data from a raster file from "Snow Data Assimilation System (SNODAS)" and convert it to a MMQGIS (plugin) grid layer (Hexagon) with QGIS. This raster file stores the snow depth ...
4
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1answer
515 views

How to start from scanned maps in qgis

What I have: A large TIFF covering parts of several contiguous sheets of the British OS 6 inch first edition. It has no georeferencing. It's just a series of scans which someone has stitched ...
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2answers
1k views

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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1answer
885 views

Access PostGIS Raster layer through mapserver

I am trying to use a cgi script calling mapserver to display a raster layer that is stored in a PostGIS database. However, only a blank white image is returned and I don't know where the problem is. ...
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1answer
190 views

Is there a difference between projecting shapefiles then rasterizing & rasterizing shapefiles then projecting?

I currently have a project where I rasterize shapefiles into simple presence/absence (1 & 0) rasters and then add each one to a running total to create a total richness raster at the end. The ...
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0answers
207 views

Calculate optimal paths between different points

How can I calculate all the possible paths between a group of points, taking into consideration the SRTM and the Slope ? I am trying to do this in ArcGIS, my dataset is a group of points (shape ...
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1answer
175 views

gdal_rasterize -at function still won't capture covered pixels properly

I'm currently using the gdal_rasterize tool in bash. My code looks like this: gdal_rasterize -l $(basename $file .shp) -burn 1 -a_nodata 0 -te -180 -90 180 90 -tr 0.1 0.01 -at -ot Byte $file ...
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1answer
204 views

How to rename rasters in directory based on field value of their centroid feature class in ArcGis?

I have a lot of rasters named like r001.tif, r002.tif and so on. There is a point shapefile with centroids of these rasters and their real name in the attribute table. I'm looking for a way or some ...
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2answers
363 views

Detect whether there is a spatial polygon in a spatial extent

Given a spatial extent (for example cbind(c(0,0),c(10,10)),I want to see whether there is a part of a SpatialPolygons falls in this extent? How can I do this? Thank you very much!
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3answers
3k views

Loading geotiffs into PostGIS using raster2pgsql

I have an issue with loading some Ordnance Survey raster data into PostGIS. I have been using the following raster2pgsql command to load a tif that I have placed in my C:\Program ...
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2answers
583 views

focal statistics with variable radius

is there an easy way to do focal statistics on a raster, with a variable radius for the neighbourhood to be searched? As in: that search radius would be stored in another raster? i tried something ...
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7answers
5k views

How can I align two non-coincident equi-resolution raster grids?

I have two rasters: a digital elevation model (DEM) and a Landsat band. The grid resolution of both is 30 m, but the grids are not coincident (see image: the dark raster on top is the DEM; the light ...
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285 views

Count raster value in a bounding box (spatial extent)

I have simple question: given a bounding box, how can I count the number of specific values (say, I am interested in the number of value == 1 ) in a raster in 1) arcpy, or 2) raster package in R?
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3answers
238 views

How to compare a set of images with a shapefile?

I have around 150 images (rasters), each one is just a map of certain "classes", e.g. pixel value 1=forest. I also have a shapefile that consists of roughly the same area as the 150 images constitute ...
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1answer
132 views

Coloring pixels based on values

I have an image where pixel values are integers, they go from 0 to 6 and I also have some 999. I want the value 999 to be transparent, which I could achieve by myself. I would like values 0 to 6 to be ...
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226 views

QGIS Georeferencer and Coordinate Systems

I'm having an issue with Ubuntu and Windows versions of QGIS where the georeferencer does not properly assign the coordinate system to the output raster. When I assign the output CRS to 'EPSG:900913 ...
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1answer
516 views

Reduce extent of raster processing in ArcPy or ArcGIS Desktop?

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 ...
6
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2answers
861 views

How to simply label raster cells?

I think the title says everything but: I want to generate a small sample raster (eg. euclidean distance or cost distance) to explain the method of cost-distance analysis, and I'd like to label the ...
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3answers
3k views

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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2answers
1k views

How to render PostGIS raster with Mapnik XML?

I'm trying to manage raster files from PostGIS, which to be rendered using Mapnik. I used raster2pgsql to load those GeoTIFF images to PostGIS, and I think the loading process turned out OK. The ...
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1answer
79 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?
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3answers
4k views

How to get values of each cell in raster attribute table?

How do I get the values of each cell in the raster attribute table. Usually the attribute table gives you the value and number of counts. But, in my case I want each cell listed and corresponding cell ...
3
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1answer
254 views

Help with null values in rasters

I need to add different boolean rasters of the distribution of some species, since we need to obtain a single file that shows the locations where there are more than one species occurring. To do ...
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1answer
558 views

Georeference problem including EPSG 102067 projection

I'm Qgis user from Czech Republic. We have a spatial national coordination system (Krovak system) having positive X axes pointing to the south and positive Y axes to the west. Many geographical ...
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3answers
1k views

Kriging with barriers in R?

I wonder if there is a way to interpolate xyz points in a raster within certain bounds using R? In ArcGIS this is called interpolation with barriers. I wonder if there is something similar in R? I ...
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1answer
573 views

zonal histogram fails to create output table when looping

Using python I'm having problems when trying to attempt a FOR LOOP with the ZonalHistogram function of ArcGIS 10.1. It works fine if I use it only for one image but it gives me this error while for ...
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1answer
227 views

How can I apply correct colours to an elevation raster?

I have a problem to display elevation data with pseudocolours. The channel 1 is from -3.40282e+38 to 149.717 . A colleague used 1.7. and it looks like it should (from blue to Red) when I use QGis 1.8 ...
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5answers
4k views

What is Change Detection and how I can perform such analysis with open source tools?

From wikipedia page: Change detection for GIS (geographical information systems) is a process that measures how the attributes of a particular area have changed between two or more time periods. ...
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2answers
238 views

Break between two raster layers (topographic maps)

I have the following problem [in QGIS]. In displaying two raster layers (topographic maps), a white area appears between the two. If I apply transparency to one of the layers, this white area still ...
6
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3answers
2k views

How do I extract a raster's extent in python?

I am looking for an easy way to extract a raster's extent in python. Currently, I am using gdalinfo and then parsing out the corner coordinates. The problem with this approach is that gdalinfo is ...
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2answers
384 views

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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3answers
6k views

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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1answer
2k views

Can I access a raster attribute table in QGIS?

I have some Python code that makes Raster Attribute Tables for GeoTiffs using GDAL. In ArcGIS I can see these attribute tables fine and they behave how I like (as classifications). But in QGIS the ...
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1answer
1k views

Export selected raster cells to polygon

I have selected certain values in a raster (roughly 1000 cells), and would like to export them to be able to create a polygon. Converting it to points first then to polygons does not work. Can anyone ...
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2answers
1k 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 ...
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0answers
185 views

Geoprocessing Service to return Multidimensional Raster from a NetCDF file

I have tried to make this work for weeks with no results. I am trying to create a model in ArcMap that uses the Multidimension Tool "Make NetCDF Raster Layer" and return a raster to which I can apply ...
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2answers
483 views

Cannot get arcpy.MosiacToNewRaster to work with list

Below I have a snippet of a much larger code that I cannot get to work and I am not sure why. It seems that I always have trouble using arcpy functions with rasters. Can anyone help me get this code ...
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4answers
575 views

Determining gradient of road segment

I've a shapefile of roads data. It contains information about terrain of road segments, i.e., hilly, flat, undulating, etc. I want to determine gradient of every road segment. I know this might ...
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2answers
449 views

Set Raster Cells Based on NoData from other Raster

I have just no clue on this problem. I want one raster to set its values to 0 or NoData based upon another raster noData or 0 values. It's like a reclassify, but between two different raster's. I have ...