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

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14
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4answers
2k views

Where can I find examples of fuzzy logic applications in ArcGIS?

The last ArcGIS version (10) includes two arctoolbox tools for fuzzy logic (Fuzzy Membership, and Fuzzy Overlay). Does anyone know where can I find some examples showing how they can be applied? ...
8
votes
4answers
1k views

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 ...
2
votes
1answer
96 views

how do I select more than one features from raster attribute table

for ex: "lc_2001" = 21, 22, 23, 24 AND "lc_2006" = 11, 31, 41, 51
5
votes
2answers
2k views

How to set the value of a pixel based on its current value?

I am attempting to set the value of a pixel based on its current value. I am using the Raster Calculator in Quantum GIS dev 1.7 trunk. For example, if the value is 0, I want to set it to 255. Based ...
1
vote
0answers
341 views

How to reproject a raster in QGIS? [closed]

I wanted to reproject raster file from UTM to decimal degree in QGIS version 1.7.1 or 1.8.0.. I could reproject one raster file before in QGIS Version 1.8.0. I have tried again, but now we cannot ...
6
votes
7answers
3k views

Extract raster values at points

How can I extract values from a raster by points. I prefer not in Arcgis. I prefer in Qgis or Mapwindow or other open source gis.
0
votes
1answer
178 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. ...
6
votes
2answers
341 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 ...
1
vote
0answers
70 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 ...
1
vote
1answer
246 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 ...
5
votes
1answer
450 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 ...
3
votes
1answer
136 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 ...
5
votes
3answers
264 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 ...
4
votes
2answers
254 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 ...
5
votes
3answers
644 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 ...
2
votes
1answer
631 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. ...
5
votes
1answer
534 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 ...
1
vote
0answers
570 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 ...
0
votes
2answers
241 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!
6
votes
1answer
134 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 ...
2
votes
1answer
373 views

accessing postgis raster data using Query layer in ArcGIS

I tried to load raster file (jpg) into post gis using the syntax provided here "C:\Program Files (x86)\PostgreSQL\9.1\bin>raster2pgsql -I -C -e -Y -F -s 102003 -t 300x300 ras_test.tif ras_test1 | psql ...
2
votes
2answers
257 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
115 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 ...
4
votes
1answer
825 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 ...
4
votes
3answers
1k views

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. ...
9
votes
1answer
337 views

Efficient raster sampling of billions of polygons (bounding boxes)

How can a raster be computed efficiently (in Python), given a set consisting of billions of bounding boxes (read sequentially from a file), and given that the raster values for each cell should give ...
10
votes
2answers
229 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?
3
votes
1answer
493 views

Merging raster data with different resolutions

I need to merge different raster datasets which have one layer and contain discrete values to a layer stack. The resolutions of the data can have any value so not only multiples of the resolutions ...
6
votes
2answers
2k 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 ...
0
votes
1answer
114 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 ...
0
votes
0answers
186 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 ...
7
votes
1answer
350 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 ...
7
votes
6answers
12k views

How to get X Y coordinates and cell value of each pixel in a raster using Python?

I’m really new to Python and I would like to know whether there is a quick method to get cell values of a raster pixel by pixel and the coordinates (map X Y coordinate of centre of each pixel) using ...
1
vote
3answers
2k views

How do I get the values of each cell in the 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 ...
4
votes
1answer
2k views

Loading a raster using QGIS into a PostGIS2.0 enabled database

Following on from my attempt to install a postgresql 9.1 db with postgis 2.0 on windows 7, I am trying to figure out how to load a raster. I have successfully loaded a shapefile, and am trying to do ...
2
votes
1answer
65 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?
3
votes
1answer
154 views

storing jpeg in spatialite database

How to store jpeg file in spatialite blob column so that spatialite gui and Qgis can recognise the format and show the image. I have created in memory jpeg from raster bands using jpeglib and stored ...
3
votes
5answers
2k views

arcpy : Add Raster Layer layer without lyr file

i wonder how i can add a raster layer to a remote (not the current) mxd file with arcpy. I need to not use a lyr file for that. For vector Layer i have the following lines working fine : mxdPath = ...
5
votes
3answers
731 views

Kriging points in a raster 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 call interpolation with barrier. i wonder if there is something similar in r?. I ...
3
votes
1answer
365 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 ...
4
votes
1answer
436 views

How does cost allocation work?

Why, when I use the cost allocation function of Spatial Analyst, is space not allocated in all input source locations (as shown in image below)? In particular, the input raster has 18 spots while the ...
1
vote
2answers
371 views

how to remove the color formed on the edge of satellite image?

my AOI requires two scene of satellite image but when I try to mosaic the images using ERDAS imagine, the color of the edge is seen forming black line after mosaic! so please how can I remove the ...
3
votes
3answers
291 views

ArcGIS 10 Raster Mosaicing versus Lizardtech Express Server

Trying to determine if I still need to use Lizardtech Express Server to mosaic rasters together or just use the Mosaic Raster Dataset function of ArcGIS 10? I know for earlier releases of Express ...
0
votes
1answer
350 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 ...
2
votes
1answer
181 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 ...
1
vote
2answers
180 views

Configuring a WorldImage data store starting from a folder containing tif and tfw files

i have a folder of tif and tfw files and i'd like to show the raster in a map using geoserver. Even reading the geoserver tutorial for this kind of datastore ...
3
votes
1answer
155 views

Change ellipsoid reference for altitude in a DEM

I have DEM data stored as RGF93 (Lambert-93) for lat/lon and NGF-IGN69 for altitude. I'm trying to change the reference ellipsoid for the elevation data (ultimately to NTF, but WGS84 would be fine to ...
1
vote
1answer
169 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 ...
5
votes
3answers
787 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 ...
4
votes
2answers
255 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 ...