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

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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 ...
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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 ...
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Finding largest number of observations within a given radius

I have the following problem: Given the location of insured properties (say houses with fire insurance), i have to find the largest sum of insured values which fit into a 300m radius. Now, my first ...
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In QGIS, how do I remove a band from a raster?

When I process a raster in QGIS it creates a second band. It appears that band has no useful data. I like to use the Raster Colours Tool and it will not accept a raster with anything more than on ...
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465 views

QGIS composer - How can I eliminate striping across transparent raster layers?

I have downloaded QGIS dev version 1.7.0-114 and I have come across some weird behaviour in the composer. I create a map with a hillshade and a transparent DEM ontop of it, pretty standard stuff. ...
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How to combine raster and attribute table in QGIS?

I have some rasters representing string categorical variables. Each raster contains integers, used to translate the categorical variables. I have also the .csv tables giving the meanings of the ...
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How to perform enhancement operations on an satellite imagery in QGIS?

I am a new user of QGIS please suggest how to perform image enhancement operations on an satellite imagery like ratioing, contrast stretching, edge engancement, filtering etc. in QGIS?
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Adding a new Coveragestore in a certain Workspace by REST

So, simple thing as it seems but I can't seem to make it work! I'm trying to add a raster data file (GeoTIFF) to geoserver via REST API, using curl on linux. REST API is working, since I created a new ...
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How can I change the class of one pixel in a classified image?

I have a classified image (I did it in ERDAS) with six categories. There are some misclassified pixels (especially high-density urban category). Is there any way that I can choose one pixel and then ...
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116 views

Raster style based on percentile QGIS

Is there a way to get similar raster styling in QGIS as ArcGIS does with classified raster data based on percentile scores? In other words, I want an equal number of pixels in one color for my entire ...
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Loading geotiffs into PostGIS using raster2pgsql

I have an issue with loading some Ordnance Survey raster data into PostGIS. I have been using the following raster2pgsql command to load a tif that I have placed in my C:\Program ...
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657 views

Confidence interval from raster data

I have raster data that represents a probability distribution, i.e. each cell has a probability value (in my case the probability that an animal may be found in the cell), and all the cells add up to ...
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How to import a raster into PostGIS?

I'm trying to follow the instructions here to load a raster into a PostGIS database: python raster2pgsql.py -s 4269 -I -r *.tif -F myschema.demelevation -o elev.sql I understand that I replace * ...
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How to extract road and building features from raster data?

I work with raster data and my task is to digitize a big image. This consumes much time just for digitizing roads and buildings! I'm looking for tools to simplify working on raster data to digitize ...
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157 views

Georeference raster in non horizontal plane

We have raster data which is generated from (vertical) walls. We would like to keep this data in a postgis database and have the spatial reference encoded "the most accurate way". Currently, they are ...
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723 views

Calculating road density in R using kernel density

I have a large (~70MB) shapefile of roads and want to convert this to a raster with road density in each cell. Ideally I'd like to do this in R along with GDAL command line tools if necessary. My ...
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301 views

Graphically depict statistical difference between thematic rasters

The graph shows a regression between two raster datasets with classified tree canopy cover: class 1 = 0-10%, class 2 = 10 - 20% ...class 6 = >60% (Figure 1, Figure 2). The spatial resolution for ...
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554 views

How to remove long linear strips from polygons?

I have a polygon layer representing impervious land cover. This was taken from a land cover raster dataset. The impervious data represents all impervious surface that is not buildings or roads. I ...
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152 views

ArcGIS color bar from pre-specified RGB values

I have a 256 item vector of RGB triplets derived from viscm (a tool for creating perceptual color bars in a CIE color space). I am not able to replicate it correctly using the algorithmic color bar ...
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How to extract vectors from map using QGIS?

I am trying to extract building footprints from a raster map (as shown in the example below). Please note that the maps are out of copyright, have been scanned and georectified by a library and have ...
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346 views

Raster smoothing

I am an italian student. I'm using ArcMap 10. For my thesis I need to simulate a debris avalanche, but in my elevation raster the avalanche deposit is included so I'd need to take it off to simulate ...
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How to calculate the flood volume using a LiDAR DEM and a HEC-RAS floodplain polygon

I’ve got a vexing GIS analysis problem which is conceptually fairly straightforward, but in reality more challenging to figure out…. Basically, I need to calculate the VOLUME of floodwater within a ...
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254 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 ...
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369 views

How can I conduct Geographically Weighted Analysis using an exponential decay function?

I have some points (representing 30 study sites) and I want to calculate the weighted mean of several variables (landscape layers) using a negative exponential decay (weights function) to give more ...
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Add attribute table to a raster in postGIS

I would like to add attributes to a raster stored in a postgis database. I use the following command to insert the raster in the database: raster2pgsql -s 4236 -I -C -M ...
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Loading raster from PostGIS DB into QGIS: succeeded yesterday, fails now [closed]

I have a PostgreSQL(v.9.2)/Postgis(v.2.0.3) database which includes raster layers (added through raster2pgsql). To open them in QGIS (v.1.8.0-Lisboa), the "Add Postgis layer" menu will not work; ...
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378 views

How to store Large Raster Images of Equipotential Surface Generation Using Monte Carlo Simulation?

I have a large (1GB+) raster that I am using as the base for the generation of an equipotential surface. This is to assess the accuracy of DEMs derived from another source. In situ observation is ...
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Debugging ERROR 999999 in Raster to Polygon Scripting?

I am trying to make a script which selects every .png file in a folder beginning with the letters "LG". I then want the scipt create a shapefile, replacing the "LG" with "SH", and then i want the ...
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Selecting 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, ...
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390 views

Breaking apart a polygon layer by unique values, creating many new layers

I have a large dataset of habitat information that I need to calculate distances from animal locations to the closest polygon of each habitat type. The way to do this, that I understand, would be to ...
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Resizing image resolution from 1000 m to 250 m in ArcGIS Desktop?

I'm beginner of ArcGIS and Remote Sensing and I have many problems with the procedure. One of them is that I have NDVI images and Soil map. Both are at the different resolution: NDVI is 250 m and ...
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Clipping a raster using a polyline or polygon

I have a large raster created from values that cover the whole United States and Alaska which are both polygon and polyline features, this raster was caluclated using Spatial Analyst IDW ...
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Reclassify raster values of 9999 to NoData, leaving all other values alone, in ArcGIS Desktop?

I have a raster in ArcGIS which has a number of cells with the values 9999, showing that the data could not be generated for that cell. I want to convert all of these 9999 values to NoData, so that ...
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Insert Raster to MXD using arcpy.mapping (ArcGIS 10)

What i want to do seems simple. But again i can't even find a workaround... I have got a lot of Raster-files (ESRI-GRID) which i need to insert into a layout mxd-file and then export the map to ...
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Is there a way to clip an image with the basic ArcView package (9.3)?

Is there a way to trim a geo-referenced air photo to an irregularly shaped boundary? I tried the clip tool shown in my attachment, but it didn't work. It looks as though the output extent field ...
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Calculating Shannon's diversity using moving window in R

I have a raster where each pixel is a particular vegetation type. I'm interested in the diversity of vegetation types around each pixel. I'd like to assign a Shannon's diversity index value (see ...
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Exporting Selected Raster Graphics using ArcGIS Desktop?

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 ...
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creating a raster of the residuals of a regression between two rasters

I am trying to create a raster of the residuals of a regression between two rasters. i.e. I would like to carry out a regression of one raster against another of the same extent and plot the residual ...
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Transforming geostationary satellite image to lon/lat

The ICARE Data and Services Center distributes the SEV_AERUS-AEROSOL-D3 product in HDF5 format (http://www.icare.univ-lille1.fr/archive/?dir=GEO/MSG+0000/SEV_AERUS-AEROSOL-D3.v1.03/). The main ...
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How to calculate the difference between two rasters in QGIS?

I have two similar rasters of the Mount Vesuvius and surroundings: one spans 20 kilometers, and the other one 50 kilometers. The two rasters are overlapping: What I would like to do is to create a ...
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Converting raster file from float to integer type in ArcGIS for Desktop?

I have a float type raster file (an NDVI made from ERDAS IMAGINE) and would like to convert it to an interger type raster file in order to use Focal Statistics function (Majority). Is there any way to ...
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How to de-noise a DSM

I have created a DEM, DSM, and nDSM from a LiDAR Point Cloud using SAGA-GIS. I extracted the appropriate returns from the point cloud, then converted to grid, and then closed gaps to fill in any ...
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Impossible to sum rasters because of nodata pixels

I have a set of rasters (.vrt) with daily soil moisture data. I want to sum the pixels of all rasters in order to have a measure by month. However, the whole world is not covered each day, which ...
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How to generate TFW files for a list of images?

I have a few digital images that are not georeferenced. E.g.: Img01.tif Img02.tif ... Img99.tif On the other hand, I have a text file, which contains georeferencing information for these ...
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Raster: How to get elevation at lat/long using python?

I was wondering if anyone has some experience in getting elevation data from a raster without using ArcGIS, but rather get the information as a python list or dict? I get my XY data as a list of ...
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Interpretation of ArcGIS Kernel Density legend parameters

In ArcMap 9.3 I've used Kernel Density to map various incidents, but the resulting shapefile doesn't display any units of measurement. Is there a good, not-to-technical source that would explain in ...
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R: overlay a line on a raster stack/brick, and get profile of cell values along the line

I've combed through R's raster functions and vignettes and can't seem to get this working. I want to specify a line/vector across a raster stack (a DEM and possibly related variables), and get a ...
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How do I get the value of the pixel under the cursor?

Is there a tool or something that will give me the value of the pixel under the cursor? What I've got in mind in something like the eyedropper tool in graphics programs that allows you to ...
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Is there a Focal Statistics (spatial analyst) tool in ArcGIS equivalent in QGIS?

I'm attempting to use QGIS v2.0.1 to accomplish the same tasks that I can do using ArcMap v10.1 and I'm running into some trouble finding equivalent tools. In ArcMap I am using the Focal Statistics ...
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How to efficiently read and reclassify many rasters in R

I've been tasked to create a suitability analysis of wave conditions in the Gulf of Mexico. I have 2 thousand or so raster files that are about 8 MB each (2438 columns, 1749 rows, 1km cell size). ...