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

learn more… | top users | synonyms (1)

3
votes
1answer
680 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 ...
3
votes
1answer
517 views

How to align two rasters of exact same cell size, extent in ArcGIS 10?

I have two raster datasets. One is already georeferenced. The second one is not georeferenced but should have the exact same extent and cell size as the first one. It is supposed to exactly overlap ...
1
vote
0answers
198 views

Raster satellite images for QGIS

When I try to apply a downloaded GIS satellite (t=rimage to Quantum, it doesn't seem to open properly. There must be a step-by step description on how this would be done effectively. Can anyone tell ...
5
votes
2answers
1k views

How to sum pixel values within a polygon zone in QGIS?

I have two layers: a raster layer and a vector layer (polygon). I can see the values of the raster pixels but I don't know how to combine them with information from the polygon layer. More ...
4
votes
3answers
322 views

Export from GIS to static html clickable hypermap?

What plugins or tools are available to conveniently export a GIS view to a html clickable hypermap? Since 2005 or so we use a commerial plugin for ArcGIS, We have a working example of the output ...
5
votes
2answers
1k views

Exporting DEM-derived rasters to CSV from QGIS?

I have been able to import into QGIS a set of raster topographic maps and the associated DEM raster maps. It registered the two for me. From there I have calculated the associated slope raster map. ...
2
votes
1answer
159 views

How extract data from a 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 ...
9
votes
3answers
2k views

Best method to aggregate 1m DEM mosaic to 10m DEM

I have a mosaic of a 1m LiDar derived DEM. I need to output a subset of the data as a 10m DEM. I am currently using the aggregate tool in ARCGIS 10 to produce a mean value for each new 10m pixel. ...
1
vote
1answer
159 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 ...
1
vote
2answers
542 views

How to import .flt files into GRASS?

I am trying to import a raster file (.flt) into GRASS. The raster file (.flt) was generated from HEC-RAS. The said raster format cannot be imported into GRASS (it shows the error "file not ...
7
votes
3answers
1k views

GDAL and Python: How to get coordinates for all cells having a specific value?

I've got an Arc/Info Binary Grid---specifically, an ArcGIS flow accumulation raster---and I'd like to identify all cells having a specific value (or in a range of values). Ultimately, I'd like a ...
1
vote
0answers
139 views

Issues with building a VRT. from OS map tiles in QGIS

I am trying to speed up rendering of OS raster map tiles in QGIS. The tiles are 1:10k Tiffs - about 130 of them. When I attempt to build the VRT it says complete, then it shows up an error ...
4
votes
1answer
233 views

How to extract most probable flow line from multiple lines?

I have to apply uncertainty principle to computing flow accumulation using Monte Carlo method. I generate raster with random numbers which represents mistakes in creating DEM. Then I apply those ...
5
votes
2answers
738 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 ...
1
vote
1answer
61 views

How to conflate terrain data?

I have an 8 km by 8 km raster of 20 m/pixel terrain data. The georeference data has been lost. All I know is that it's within 100 km of Smithers, BC. I realize that this might involve some very heavy ...
3
votes
3answers
522 views

Is there a “Tabulate Area” function in QGIS?

I have a raster file about land usage in northern italy (crops / urban areas ecc..) I have defined some buffer zones around some given points of a vector layer and I'd like to calculate the % of ...
2
votes
0answers
133 views

How to geocorrect in qgis?

I need to fit a utm wgs84 tiff raster to a topomap in the same projection. I use GCP and it invariably fails. The first raster uncorrected rater superimpose well, the "geocorrected" raster is ...
3
votes
1answer
181 views

gdal_warp of multiple rasters keeping maxium intensity value

I have multiple rasters which overlap eachother geospatially but do not completely occupy the same space. I can combine them with gdalwarp like: gdalwarp -s_srs EPSG:4326 *.tif larger_output.tif ...
1
vote
3answers
351 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 ...
2
votes
2answers
1k views

How to classify/style rasters correctly?

I am using a GeoTiff raster data and trying to classify it. I was wondering what are the techniques that I can use in QGIS to do this? The raster I have looks like but I tried the reclassify tool ...
9
votes
2answers
1k views

What to do with -3.4e+38 nodata values?

I am trying to process some bioclimatic raster files, such as can be downloaded from http://www.worldclim.org/current (bioclim set). They seem to have nodata values set to -3.4e+38 according to QGIS ...
5
votes
1answer
165 views

Getting ArcMap to display rasters properly first time

This is a very basic question, but as I've self-taught most of my GIS skills this is still a gap in my knowledge. When I load a .tif raster into ArcMap, most of the time it requires re-exporting to ...
4
votes
5answers
583 views

How to save a raster and vector into a single PNG file in GRASS?

I am trying to save a raster and vector into a PNG file. The vector is overlayed on top of the raster map. I was only able to save the raster file into a png using r.out.png but without the vector.
2
votes
0answers
65 views

Cubist Add-In for ArcMap

I'm looking for an ArcMap add-in that will create a raster based on rules from RuleQuest Research's Cubist .model files. Ideally, the add-in will give the user the option of matching input raster data ...
3
votes
2answers
449 views

How to create a standard deviation map from three rasters in QGIS?

I have 3 normalised (0-100) raster maps. Is it possible to get a map which shows the standard deviation? I'd like to see the areas with smaller and higher std deviation. Thank you!
2
votes
1answer
240 views

How to repair broken Mosaic Dataset data sources?

I have a question. My computer has been replaced with a new Xeon Workstation. Before that, I had a temporary workstation and had ArcGIS 10 on it. While I was waiting for the new workstation to be ...
8
votes
5answers
295 views

How to ensure uniform colour for DEMs?

This is a silly question, but one I've been trying to figure out for a while. I have two Aster DEM tiles, one next to the other. How do I ensure uniform colour for both?
2
votes
2answers
341 views

How to get easting & northing of cell in raster using ArcPy?

It might be very simple task. But I would appreciate if someone can comment on How I can get easting and northing of a single cell raster using arcpy as this value is used for in further steps. ...
0
votes
1answer
599 views

Problem with raster calculator [closed]

When working with raster calculator there is an error 000539? The program failed to create a common raster map. I don't know what to do. I did the same in school without any problems. But now, on my ...
4
votes
2answers
341 views

Find locations of raster maximum within polygons: Basin Delineation

I'm trying to identify the Location (lat/lon) and upstream area of every raster point that flows into the Arctic Ocean (there are a lot so it has to be fully automated). I'm starting with the ...
3
votes
1answer
346 views

Looking for Mid-Holocene (~6000 BP) bioclim dataset

I am trying to obtain climate data for the Mid-Holocene (~6000 BP), preferably in the bioclim (19 bioclimatic variables) raster format. The worldclim.org website lists this dataset based on the CCSM ...
1
vote
1answer
140 views

How to correlate raster map and elevation data?

I have been provided with a set of raster maps. Thanks to another helpful user here I have been able to acquire some elevation data for the same region from gis.utah.gov in asc format. Now I need to ...
2
votes
2answers
156 views

Coordinate system of a raster file to be introduced for transformation

I am working on raster data using GDAL. When I extract coordinate system information of the files I got this: PROJCS["Geostationary_Satellite", GEOGCS["GCS_Unknown datum based upon the custom ...
3
votes
3answers
504 views

climatic data from MODIS or other sources

I'm looking for climatic information in the form of raster like MODIS daily LST (Land Surface Temperature) data. I'm looking for other parameters like precipitation, humidity, air pressure and so on. ...
4
votes
2answers
727 views

Annoying little line in color ramp legends - how do I remove it?

This was never a problem with ArcGIS 9 but it appears that in 10.0 Esri has added small horizontal lines as the default when including color ramps in legends. I want to get rid of these annoying ...
5
votes
2answers
240 views

How to modify raster pixel inside a polygon?

I would like to set to novalue all the pixels of my raster inside a polygon. I'm trying the gdalwarp command line with -cutline option. But this command extract the values of my raster inside the ...
2
votes
1answer
106 views

From Raster to Masked and Filtered Polygon Vector

I have a set of rasters (geologic risk) from which I want to extract zones with a specific color, clipping them with a polygon (administrative borders), outputting a shapefile. I'm using QGis (and ...
3
votes
2answers
525 views

set geotiff 0 values to nodata

Is there a way to set all the 0 value pixels on a raster to nodata using gdal or qgis?I world like to use fillnodata to fill some holes, but holes are set to 0,so I need to delete them first
3
votes
1answer
2k views

Creating Isolines from point Data

I'm quite new with ArcGis 10 so I’m having difficulties with something that may be simple to some. Anyway I have a list of bores that I’ve plotted using coordinates. Now I need to draw a single ...
1
vote
0answers
70 views

GRASS error reading raster map: request for row 1 is outside region [closed]

I'm a rather inexperienced GRASS user, and am trying to use an addon module called r.geomorphon (see http://sil.uc.edu/downloads.html#software). I've managed to get it installed and am trying to run ...
2
votes
1answer
217 views

Raster Analysis - Identifying features from Raster

I have an IDW, tension spline and hill-shade rasters that show an archaeological landscape and from these rasters I want to identify new features which are seen in the landscape as depressions. And ...
4
votes
1answer
352 views

Recoloring geotiff for visual presentation

I have a rather big Geotiff. It is the mosaic of four RapidEye satellite images. They are all a bit bland/grayish. When combined I would like to freshen up their colors so that they are more visually ...
2
votes
0answers
125 views

Sextante - SAGA- Shape to grid question?

I have a vektor shape (Index 1-5). After using the saga tool (shapes to grid) I'm getting a raster (values 1-5). The problem is that the NO DATA area is defined as 129. Is it possible to set 129 as no ...
3
votes
1answer
607 views

GeoTiff convert to PNG with transparency

I need to convert a GeoTIFF image to PNG format with "NoData" pixels in the original image being transparent in the output. Is there any tool particularly in ArcGIS ArcToolbox or GDAL for this ...
2
votes
1answer
352 views

Querying PostGIS Raster with MultiPoint

For one of my projects using PostGIS 2 I have a table with GPS tracks (igc_files). It holds records including a MULTIPOINT() column that has about 1,000 points for each record and a column that has an ...
2
votes
1answer
227 views

joining a table from zonal statistics as table with a layer, problem with reserved names

I have a raster file (percentage of total forest killed) and a shapefile with polygons (municipalities). I thought as a first step I would like to find out which municipality shows the greatest ...
2
votes
4answers
1k views

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
votes
2answers
653 views

How to batch import GDAL supported raster files into GRASS?

I am trying to import some GDAL supported raster files into a binary raster map layer using the r.in.gdal module from QGis Grass tool. As I have multiple files to import, I would like to batch import ...
5
votes
1answer
514 views

How to get pixel size/cell size of raster layer?

After much searching, I've still not been able to figure out how to perform what seems like a simple function: I'd like to get the pixel size/cell size of a raster layer using PyQgis. Is there any ...
2
votes
1answer
341 views

Creating a quality raster map in QGIS?

I've got 2 raster maps (both with the same values: 0-100). After calculating the average I need to know how precise the map is. Is there any tool in QGis? I try to explain my problem in another ...