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

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3answers
230 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 ...
0
votes
1answer
127 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
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0answers
208 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
444 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 ...
6
votes
2answers
581 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 ...
6
votes
2answers
2k 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?
3
votes
2answers
852 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 ...
2
votes
1answer
75 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
3answers
3k 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
votes
1answer
240 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 ...
3
votes
1answer
480 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 ...
5
votes
3answers
970 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 ...
0
votes
1answer
459 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
210 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 ...
19
votes
5answers
3k 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. ...
1
vote
2answers
213 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
votes
3answers
1k 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
333 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 ...
8
votes
2answers
4k 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 ...
4
votes
1answer
1k 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 ...
5
votes
1answer
827 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 ...
2
votes
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 ...
3
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0answers
161 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 ...
1
vote
2answers
390 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 ...
1
vote
3answers
420 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 ...
0
votes
2answers
357 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 ...
3
votes
3answers
933 views

How to speed up Postgis raster layer display in QGIS?

i've been importing some digital orthophoto geotif files into postgis 2.0.1 via raster2pgsql tool (i also made 3 levels of an overview table - pyramid). Then i tried to import the layer into qgis via ...
2
votes
2answers
173 views

Is there anywhere that I can obtain global UV data in either raster or vector format?

I'm looking for some UV data (currently with no spatial or temporal resolutions in mind, but ideally split into UV-A and UV-B) for the whole earth. Can anyone recommend a source for data like this or ...
0
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0answers
193 views

QGIS Invalid Data Source in raster calculator

I just installed QGIS and am new to it. I want to use the raster calculator, but after assigning a name to the output layer QGIS tells me "Invalid Data Source" and "filename.tif is not a valid or ...
8
votes
6answers
5k views

Rasterfile clipping error: Cannot compute bounding box of cutline

I have a raster file and want to clip it, a vector file is supposed to be the mask layer. I use the most obvious method (Raster->Extraction->Clipper). No matter what I do, I get this error (see pic): ...
2
votes
0answers
311 views

Can hdf4 images be used in QGIS?

I'm trying to use hdf4 raster image in QGis 1.8. This image come from the MODIS satellite. I've loaded the file, it appears on the layer window bu it is impossible to see it on the display window. ...
6
votes
3answers
2k views

How can I select vector features that overlay raster in arcpy?

I have two datasets: point feature class and raster (stored in file geodatabase). The spatial extent of the raster is smaller than the point dataset. Is there a way I could select (or create new, ...
10
votes
2answers
368 views

What are the advantages/disadvantages of populating a PostGIS database with Raster information?

...as opposed to keeping the rasters as locally stored GEOTIFFs? I have a large project that will require making available approximetely 50,000, 10mb GEOTIFFs as WMS to an OpenLayers based web map. ...
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vote
0answers
189 views

Reclassify ESRI raster using variables from a SQL Server table (connecting with pyodbc)

I am trying to reclass a raster file (representing vegetation and land cover types) using values stored in a SQL Server Express table. I have a set of ~400 species records in the table, with each row ...
4
votes
1answer
1k views

How do you add a long list of rasters together in Python?

If you have produced a long list of rasters (lets say 50) and want to add them together, is there any shorter way to write in python rather than typing all the inputs, like so: outRas = inRas1 + ...
4
votes
1answer
595 views

Are there limitations using a PostGIS out-db raster?

I have been trying to import a large raster into a PostGIS 2.0 database and hit a few stumbling blocks. Initially when I tried to import the raster using raster2pgsql, I would receive the following ...
0
votes
1answer
159 views

QGis : superimpose 2 rasters georeferenced (adjustment)

I am pretty new in QGis and I encounter the following problem. I have 2 rasters, let's say, "cadaster" and "tranchot". The raster "tranchot" was georeferenced from the raster "cadaster" with QGis. ...
2
votes
2answers
738 views

Conditional combining of multiple rasters to produce one output using Python?

I have two rasters for same spatial extent and need to compare both rasters cell by cell and produce one output raster. Each has 10 land cover classes. Based on those 10 classes the comparison should ...
3
votes
0answers
113 views

How to view Esri GRID format file in wxpython file browse window? [closed]

I'm trying to browse for all kinds of vector and raster data using a filebrowsebutton. The problem is I don't know how to let the browse window see the Esri GRID files (which contains a folder and a ...
8
votes
1answer
2k views

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 ...
2
votes
1answer
1k views

Creating a raster map using Excel file and calculating averages

I am working on my Master's thesis and have thought about using ArcGIS to create a raster map of latitude/longitude (0 to 360 degrees) temperature data (in Excel format). This temperature data ...
2
votes
2answers
1k views

How do I use ranges for raster colour map in QGIS

I have a raster layer in GeoTIFF format, with continuous data values between -1 and +1. For the colour map, I would like... >0 to be green = 0 to be grey <0 to -0.25 to be pink <-0.25 to ...
2
votes
0answers
139 views

3d arcgis raster .tiff image to CFD software

i am trying to export 3d raster image prepared in arcgis to cfd package such as Fluent. I was wondering if any one has experience to convert raster image to autocad 3d format, stl, vrml or any other ...
4
votes
1answer
276 views

Stripes in Landsat-image after topographic correction (SAGA)

I got stripes in my topographic corrected Landsat images (see second image below). I used SAGA GIS 2.0.8 at xubuntu 12.04 Image and DEM are in the same projection, tried it with EPSG:32636 and ...
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vote
0answers
110 views

Corrupted rasters after import into ArcGIS FGDB

I have been seeing a number of corrupted rasters recently after importing them into file geodatabases (FGDB). The image below left shows a .tif prior to the import, while the image to the right shows ...
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vote
0answers
534 views

How to add ECW support to GDAL bundled with PostGIS Windows

I'm currently trying the new raster functionalities of PostGIS 2.0 and I successfully imported some GeoTIFF file into PostGIS (although it only find one band so it's all black and white for some ...
2
votes
0answers
509 views

Output raster extents when using the Spatial Analyst Extract By Mask tool to clip a raster

I am using ArcGIS 9.2 and I have a simple python script that does the following : Loop over a polygon feature class (shown in red in the image below) For each record, create a feature layer to ...
4
votes
2answers
1k views

Rasterize a vector layer in PostGIS

Related to this question asked here on gis.se and this thread on postgis-user, has anyone worked out a good solution for in-database rasterization of a vector layer using PostGIS? It sounds like the ...
6
votes
3answers
2k views

How to smooth / “reinterpolate” a raster with GDAL?

Short: I want to change the resolution of a raster and smooth the gray ramp like shown in the images bellow. The preference is to use GDAL, PIL or Numpy. Description: I'm kriging points into rasters ...
5
votes
4answers
4k views

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 ...