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

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4k views

What is Lanczos resampling useful for in a spatial context?

GDAL includes a resampling method beyond the normal mix of nearest neighbor, bilinear, cubic and splines: "Lanczos windowed sinc resampling". I understand that its a convolution filter, but unlike ...
3
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3answers
286 views

What DEMs does QGIS support? + DEM data sample

I am working on QGIS rasters. I want to know about DEM file formats supported by QGIS. I know that QGIS can read the GDAL supported formats. but what is GDAL supported format ? Does QGIS support the ...
1
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1answer
283 views

Polygon to raster without losing any polygons

I'm trying to convert polygons to raster. But the output raster dataset doesn't have polygons which went into as input data. I need all the date in the attribute to follow with to the raster dataset ...
2
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1answer
151 views

Change Values of Georeferenced Raster

I am using QGIS to georeference B&W images. I have now done this and would like to set the black surround of the image (as a result of the georeferencing) to transparent but this does not work as ...
0
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1answer
880 views

How to convert a bil image into grid in ArcGIS?

GIS beginner here. I've downloaded RFE data from FEWSNET. It's a compressed file which includes .bil files. Now i want to convert this ".bil image" into a grid to use the precipitation data in an ...
5
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1answer
1k 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 ...
0
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1answer
79 views

GDAL clips raster at wrong position

I try to clip raster data with GDAL (in fact I am using QGis, which produces me a command line for GDAL) The raster has been transfored to EPSG:3857, which is also the projection of the shape file ...
1
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0answers
320 views

Cannot add the PostGIS raster layer with QGIS

I've imported some raster data in PostGIS database with the following command: raster2pgsql -s 31468 -I -C -M -t 50x50 /home/stefan/Quantum\ GIS/Neumarkt/NM_NW.tif public.demelevation | psql -U ...
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2answers
534 views

How do I import OS raster tiles into QGIS at the correct scale?

I have some tiles of OS raster mapping and their associated TFW georeferencing files. The GR files are in the same folder as the raster data and have the same names, ie TQ21.tif/TQ21.tfw. In QGIS ...
1
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1answer
133 views

How can I turn QGIS into a simple hiking planner?

I'd like to try and turn QGIS into a simple hiking planner. I have found and worked out how to import OS raster mapping at the correct scale and how to add freehand vector lines to the mapping, which ...
1
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2answers
65 views

Adding 'freehand' data to raster mapping in QGIS

Having just worked out how to import raster mapping into QGIS at the correct scale, I'd like to now add useful information to the map like marked routes, labels etc. How can I do this in a 'freehand' ...
1
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0answers
329 views

How To calculate raster land cover inside overlapping buffer zones?

I am working with a raster land cover file that consists of several land cover types (e.g. forest, buildings, grass ect.) in total there is 40 different land cover types. I have 1200 bufferzonen ...
1
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2answers
454 views

gdal_calc.py outputs huge files

I think this is a general enough question to apply to more than just gdal_calc, but perhaps not. When I run gdal_calc.py -A map.tif --outfile=deforestation_00-10.tif --NoDataValue=0 --calc="A >= ...
5
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3answers
2k views

Extract raster by mask output does not completely overlap the mask

I have a flow accumulation grid and a shapefile containing catchment areas. Now I want to do some calculations on them so I need to extract data from cells in the raster adjacent to certain catchment ...
0
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2answers
335 views

Add a time dimension in ESRI mosaic raster dataset

I am in the process of creating a script to pull daily .asc files from a ftp server, convert them to a raster format, and push them into a mosaic raster dataset. Ultimately, the raster dataset will be ...
2
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0answers
160 views

Can I update the service on ArcGis Server programmatically?

There is Windows Service. This service adds user raster data to the Raster Dataset in sde database. The Raster Dataset registred on the ArcGis Server. This Raster Dataset also was publishing on ...
0
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1answer
305 views

How to conditionnally assign a new value to pixels of a raster image?

Given a topographic GIS raster of one country crop.tif: Given a know pixel value such as elevation (z) is +73 : $ gdallocationinfo crop.tif 1 1 -valonly > 73 Given an elevation threshold n = 50 ...
0
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2answers
214 views

How to georeference a raster based on identical, already georeferenced raster

I have two identical rasters, one has been georeferenced, the other has not. I would like to georeference the second raster automatically using the first one. I do not want to create links by hand and ...
2
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1answer
181 views

Convert lat/long four corners data to raster

I have a data set in the following format.each row represents the coordinates of the four corners of a cell and the last column is the value associated to the cell. lon1 lat1 lon2 lat2 lon3 lat3 lon4 ...
0
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2answers
294 views

Gdal: How iterate through all pixels of a raster image?

Given a topographic raster image. How to iterate through all pixels of this raster image ? Solution preferably with gdal, in console. Some other libraries/script could be installed. Related: ...
0
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1answer
326 views

Gdal: How to get a pixel's value from raster image?

Given a topographic raster image. Given a pixel's coordinate in pixel/lines or geocoordinate. How to get it's pixel value ?
2
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1answer
173 views

How to work with flt & hdr files

I have been working on a vector-based spatial analysis in R using shapefiles. I wish to use some environmental data that is downloadable, however it is only available in raster format (FLT & HDR ...
2
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1answer
742 views

Filtering a raster by pixel value ? (Qgis)

I have downloaded Globcover data in GeoTIFF format. I want to create a new grid which only has values where the Globcover data (the only band in the TIF file) has one certain value (==190). Can I do ...
0
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0answers
73 views

Vector/Raster Intersection - Speedup and replacement for ST_Centroid

I have some raster data which is the altitude above sea level and also some vector data which represents building outlines. What I want to do is grab some buildings outlines and fetch all the raster ...
2
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0answers
192 views

How to render a transparent raster layer on top of one or more vector layers with PyQgis?

I been trying to render a map with a 3 vector layers and one raster layer. The idea is that the raster layer should be on top of the other 3 vector layers. The problem is that even when I add the ...
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1answer
2k views

Import PDF to qgis

i have a PDF containing a region of Baltimore city that contains lots of polygons in it. you can download it from here: ...
3
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1answer
356 views

How is slope of a surface in an arbitrary direction produced?

I am currently developing a program that requires that I calculate the slope for each cell in a DEM. However when I try to understand the algorithm to be used I get stuck trying to understand exactly ...
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1answer
656 views

Problem merging two rasters in Qgis

I have two rasters in Geotiff, same CRS. I tried to merge them and I have this error code ERROR 4: `C:/Anita_Tepoztln/Rasters/e142.tif' does not exist in the file system, and is not recognised as a ...
1
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1answer
146 views

Aggregating a raster to fit a polygon grid

I am working at the scale of 10 square km grid cells for the UK, and have a polygon layer of the Ordnance Survey 10k grid cells in ArcGIS. I have another layer of the human footprint index, also for ...
3
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0answers
284 views

How to calculate the distance to multiple locations from each cell of my raster?

I'm working with Arcgis 10.1 and Python 2.7.2 How can I calculate the distance to multiple locations from each cell of my raster? I tried euclidean distance but it only provides the distance to ...
0
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1answer
97 views

Integer rasters referring to the same scale

I'm using ArcMap 10. I want to display the area of simulated avalanches. I want this area to be divided in different colors depending on the thickness of the deposit. I managed to do that. But I want ...
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0answers
75 views

QGIS merge rasters error

I've been trying to merge some raster tiles at work and I've been getting an error message saying I don't have the correct permissions. This works fine on my home pc. Any obvious reasons for this? ...
11
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2answers
452 views

Converting ascii windspeed files to rasters

I have been trying to convert windspeed files to rasters without success. It was discussed in an Arcgis forum which I followed. This involved replacing semi-colons with spaces and adding a header. I ...
2
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3answers
455 views

Raster dataset doesn't exist error

Dataset exist and I am able to get statistics from ArcGIS python window. But it failed as a script with error: ERROR 000865: Input raster: C:\temp\ras does not exist. I have tried following ...
0
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2answers
425 views

How do you use 'reclass' in GRASS?

It could be user error, but for some reason, the reclass tool is just hanging and hanging... QGIS 1.8 Compiled against GDAL/OGR 1.9.2 Ubuntu 12.04.1 Running the tool from the Sextante toolbox Input ...
2
votes
1answer
170 views

How to get mean of pixel values within a buffer zone around current mouse position in QGIS

for a qgis 1.8 python plugin I want to query the mean of all pixel values of a raster layer within a defined buffer around the current mouse position, not for an existing point layer. For the buffer ...
0
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1answer
173 views

how to create a new raster from one field of a raster with several fields in a RAT

I have a raster with an attribute table containing many fields. I want to create a new raster from one field using arcGIS 10.1.
1
vote
1answer
171 views

Can't view PostGIS rasters after changing schemas

I have loaded a few rasters into the Public schema of a PostGIS 2.0 database. Using the db manager in QGIS 1.8.0 I can add the rasters to the map canvas. After moving the rasters to another schema in ...
1
vote
1answer
66 views

Area surface doesn't match

I have three municipalities with a total surface of 178 sq km. I want to analyze land cover of those municipalities using both LANDSAT images with a pixel size of 30 x 30 meters and SPOT with a pixel ...
3
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0answers
253 views

Getting coordinates of pixels

I want to compute an area of certain object on a picture using Monte Carlo method. The picture shows some shape on white background. To do so I figured out that I'd get the coordinates of non-white ...
6
votes
3answers
3k views

ArcGIS Export Selected Raster Graphics

I'm having a problem exporting raster graphics using ArcGIS 10. It seems simple enough, but for some reason I cannot get ArcMap to work with me. Here are my steps: Add a raster to ArcMap Open the ...
0
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0answers
159 views

How to create a raster mosaic from many asc files

I am trying to create a raster mosaic (in ArcGIS 10.1) as I am working with many asc files - I am trying to put all the different tiles together in order to run a view shed analysis. I have been told ...
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0answers
107 views

PostGIS raster functions aspect and slope slow

I am trying to compute the raster and slope values from a DGM table (8184 x 5159) imported from tif file tiled in 500x500 tiles. In my query in which I merge the DGM table with a vector (point type) ...
5
votes
4answers
3k views

Quantum GIS and ECW images?

How might I enable Quantum GIS to read ECW imagery? At the moment I'm mostly concerned about this on Ubuntu 10.4 amd64, but I also use WinXP & Win7.
6
votes
6answers
524 views

Interpolation of multibeam bathymetry

I'm trying to make a 3D map with multi-beam bathymetry (65536 features, xyz), but it seems that the interpolation methods are too rigid. I need to smooth the data so it looks more natural and ...
2
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0answers
39 views

simple raster format to use in Web applications?

I'm building a Web application in which users create and edit very coarse raster data. They're assigning values to cells in a georeferenced grid. Right now I'm storing the values in a multidimensional ...
0
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0answers
144 views

Assign spatial reference for 1000 different ECW raster datasets using 1000 different *.prj files through python programming or .net

I am having 2000 ECW raster datasets without spatial reference and also I have 2000 *.prj files in another folder. I know only the way as right click on raster datasets-->properties-->Spatial ...
0
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1answer
85 views

How can I establish patterns, hotspots and clusters?

AS a crime analyst you need to establish a few maps that would help police to do targeted patrols, I've given data of suburbs, roads, incidents, boundaries. How can I establish patterns, hotspots and ...
0
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1answer
175 views

Help loading Raster to PostGIS 2 .0

Similar questions have been asked, but since my reputation is not enough I am unable to comment on answers. (The following is from an answer by nickves for this question Loading raster data to ...
0
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1answer
325 views

How to batch merge rasters using FOSSGIS tools?

I'm working with QGIS 1.8 (gdal 1.9.2) and GRASS 6.4.3...but on Windows 7. I "just" want to merge my raster. I've got a folder with 50 GTiff raster from Lidar data. The aim is to merge raster ...