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

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OpenLayers (allOverlays): Vector layer not rendered without raster layer beneath it

This is another newbie question. I'm trying to create a map using OpenLayers that comprises only of vector layers from a WFS server. However, I'm thwarted because my vector layer won't render unless ...
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1answer
376 views

Recreating A Lat/Long Grid Using a Specified Formula

I'm trying to recreate the Gridded Mercury emissions 2000 (0.5 x 0.5 degree grid) designed by the Arctic Monitoring and Assessment Programme. The file is in ASCII format, but without any coordinates. ...
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2answers
294 views

Clip raster to multi raster

I have a raster aerial photo. I have county wide parcel data. I want to clip/screen shot the raster at each individual parcel. Think of this application - a post card with an image of your house ...
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1answer
432 views

How to create aux.xml file?

after starting to use MOBAC to create offline background maps I found the aux.xml files very useful as QGIS automatically sets the CRS so this would be very useful for my colleagues with smaller GIS ...
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5answers
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Multicriteria Analysis : how to?

I have to do a multi-criteria analysis to answer the question : "which is the best lot to develop". A few of the criterias are : distance of the nearest bus stop (point layer with bus stops) ...
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2answers
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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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2answers
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How can I save raster dataset using arcpy

I'm trying to save filled raster object to geo database by my specified filename. import arcpy from arcpy import env from arcpy.sa import * env.workspace = r"C:\GIS ...
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1answer
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calculate building density in ArcMap

I have two questions related to calculate building density. I need to calculate the building density in a map which Data is in shape format. The buildings and the area are in two different layers. ...
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2answers
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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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0answers
181 views

How to read pixel values from an image server layer with ArcObjects?

I'm having a problem with reading pixel values from the image server layer. The image server layer class implements IRasterLayer, so when I tried to read pixel values using IRaster2 obtained through ...
5
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1answer
143 views

Smaller raster file natively supported by GeoServer

I have a 800MB GeoTIFF file generated from (ASTER GDEM v2 tiffs) depicting relief to be used as part of a basemap for an application I am working on. I intend GeoServer to serve this raster but it's ...
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1answer
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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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2answers
386 views

TIFF, Grid, FGDB Grid, etc. - what performs better in ArcScene animation?

I am creating a flyover animation in ArcScene and I would like my surface raster to be rendered in full resolution (an exported function raster dataset - a blend of shaded relief and high resolution ...
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1answer
196 views

Phenological event extraction in IDL

I’m doing phenological study using a threshold method in IDL. I have a twelve-band image in 2005 (format is in .tiff not ENVI format). Twelve-band means that monthly images (Jan to Dec) have been ...
2
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3answers
996 views

Batch script converting and resampling orthophotos

I would like to convert more than 300 orthophotos produced at scale 1:8.000 with a pixel size of 0.8m X 0.8m from Ecw format to Tiff format and after resampling pixel values. My aim is to batch ...
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1answer
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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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2answers
1k views

How to vectorize a Raster-Classification? (qgis, grass)

I classified my raster-DHM into elevation levels using colormap. Its not a "real" classification, just a colormap. So I cant vectorize the classes to get polygones for every class. Whats the best ...
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1answer
726 views

Get a pixel value

How can i do this operation: I want to get a pixel value fro the satellite image (Landat, GeoTIFF, 7 bands) using qgis-python. What operators should i use? (for example in qgis's Python Console) ...
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2answers
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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. ...
7
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2answers
588 views

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 ...
7
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4answers
3k views

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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2answers
195 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 ...
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2answers
264 views

Raster calculation confusion

I need to do some raster calculation, I've been trying to make it work but I am not sure everything is working properly. I need to apply a formula, but I am unsure if I am doing it properly. The ...
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0answers
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identify the fraction of raster cells and listing all the cell values in every polygon

In Arcgis 10 I have a netcdf file that maps the fractions of cropland in the world from 1700 to 2007. I extracted the years that i needed as raster layer format (continous data from 0 to 1) and now, ...
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1answer
281 views

Multishading: bring them together to one Raster-Image

I made a multi-hillshade with 4 different light-directions and colors and stacked one above the other, each with its own transparency. Now I want to "save" the result in one raster-image. Whats the ...
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1answer
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How to rasterize SpatialPolygons in R?

I'm trying to extract the bathymetry values of my area of interest from a world bathymetry raster layer using the 'rasterize' function in the {sp} package. *Edits: I found the 'extract' function ...
3
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1answer
601 views

Cell calculations; QGIS,GRASS,GDAL,SAGA

I recently asked a question about trying to calculate the slope over distance (manually) using QGIS, but then I came up with another way of solving the problem, but I would have to get some help for ...
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1answer
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ArcMap, Make Grids and Graticules Layer example

I'm trying to use the Make Grids and Graticules Layer tool in ArcMap (have a ArcInfo license). I'm looking for a basic example like in North America. eg. 1.)Start with empty map 2.) Set data ...
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2answers
652 views

Calculating slope over distance from raster

I am sitting with an elevation raster, trying to produce a calculation for slope angle. I have a cell size of 2,-2 and I am trying to figure out how to calculate cell value difference between adjacent ...
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1answer
231 views

managing .adf's in QGIS or SAGA?

I have a few .adf's that I aquired from a fellow using ArcGIS (as I understand, this format is a specific ArcGIS format). I can open it up in qgis but their relative geographic position is off, seems ...
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1answer
1k views

How to generate smooth contours from cropped raster?

I’m trying to create contours from a raster layer in QGIS. On my first attempt, I cropped my raster layer in Photoshop and reimported it, but it lost coordinate data I think. I made the contours ...
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1answer
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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 ...
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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 ...
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2answers
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How can I calculate the number of raster pixels within polygons?

I have two layers, flood area (flood.img) as a raster and flow direction as polygons. Would you please help me in calculating the number of pixels in each flow direction polygon? I want to get the ...
2
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1answer
236 views

Raster format with rotated cells - no resampling

Is there any way to rotate a raster w/o resampling? I am aware that rasters are always 90 deg perpendicular grids, but is there any file format or methodology that allows for a diagonal raster - one ...
3
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2answers
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Reclassify raster values of 9999 to NoData, leaving all other values alone, in ArcGIS

I've got a really stupidly simple question, but I can't seem to work out how to do it. I have a raster in ArcGIS which has a number of cells with the values 9999, showing that the data could not be ...
4
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1answer
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How should I correctly exaggerate a hillshade raster (ArcGIS10, Spatial Analyst)?

I once wanted to generalize a high resolution raster and instead of MEAN i accidentally selected the default SUM technique, using a cell factor 5 (Lidar DEM is 1m resolution). When I used this result ...
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1answer
334 views

Can I create a legend of a map that I had get from a WMS?

Can I create a legend of a map that I had get from a WMS? Can I create a legend of a raster map with Qgis version 1.7.4, or only with the 1.8 version?
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4answers
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problem in raster data with arcmap 10

I have a problem when trying to load raster data (a TIF) in ArcMap. ArcMap 10 instantly shuts down and the well known window appears "ArcGis Desktop has encountered a serious application error and is ...
5
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2answers
401 views

Adding noise to a raster

I want to add some fine-grained noise to a raster in an automated python process (i.e. I do not want to use Photoshop or GIMP). I looked at PIL, but unless I'm mistaken, it doesn't seem to have any ...
2
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2answers
445 views

How do I create a negative to positive value raster with neutral 0?

I have a raster layer with a band with values from -137 to 9229. I want to create a color scheme showing how far from 0 the positive numbers are in one color, and how far from zero the negative ...
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2answers
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can't generate/display signed float values using python/gdal

I'm trying to create a raster with signed float values as the pixel values and display the results in MapWindow on windows. What is the proper gdal band type to use? I've tried both gdal.GDT_Byte ...
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2answers
130 views

Display Rectangular Data Grid

I'd like a Linux program which displays ASCII ArcGrid files (NxM rectangular ASCII data grids which may have either integer or floating point values). There is no practical upper or lower limit to ...
3
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1answer
458 views

Raster data array output flipped on x-axis using python/gdal?

I'm trying to create a raster using the python gdal libraries and I've gotten to the point where data is being output, but the output data is flipped on the origin point's x-axis. I know I must be ...
3
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2answers
817 views

Determine direction of rivers, which villages lie upstream and which downstream

I want to determine which villages lie upstream and which villages lie downstream big cities built on the side of rivers in Indonesia. I have the .shp file of villages and cities, the .shp file of all ...
3
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1answer
157 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 ...
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Get Raster Values from a Polygon Overlay in Opensource GIS Solutions

I have two layers. A polygon-shape-layer with many tiles and a raster-layer containing CORINE 2006 land cover with many categories in a colourmap. I want to obtain for each polygon in the shapelayer a ...
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3answers
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Why is my mosaic of rasters a big, black rectangle?

I downloaded NED rasters from USGS, and I now want to mosaic all of the rasters into one. I used the Mosaic to New Raster tool, but the output is a big, black rectangle. Am I missing something? I feel ...
2
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1answer
300 views

Get raster field names in R

Does anyone know how I can extract the raster field names (VALUE, COUNT and other existing field names on a categorical raster file) in R? I am using the raster package to load the raster files.
4
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3answers
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How to Clip a Vector File based on certain Raster Values?

I need to clip a vector file based on certain values of a raster (Slope > 2%). I can´t find a direct way to do it. Trying to vectorize the raster first didn´t work. Is there any tool (ArcGIS or ...