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

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Merging USGS DEM files in ArcMap?

I'm trying to merge my DEM files into 2 separate files, one will have 4 files and the other will have 3. I've been reading every post from when someone asked this before for over an hour and I'm still ...
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25 views

How does ST_SnapToGrid work using nearest neighbor interpolation?

I have rasters in a PostGIS database that are not necessarily aligned (some rasters offset from the grid). I want to use ST_SnapToGrid to align all rasters to the same grid but have some questions ...
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How does `ST_Union` treat NULL values in a raster?

My question is about how ST_Union of rasters containing NULL values are handled. For example suppose I have two rasters that intersect but the values of the intersection are NULL in one of the ...
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34 views

How to extend raster data for larger boundary?

I am working on serveral raster data, but some of them are not fill data exactly with intended boundary (as shown in the picture below). What i want to do is firstly extend the raster data to intended ...
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42 views

Bleeding/fuzzy edges when adding raster to mosaic in ArcMap

I'm a relative newcomer to ArcMap but have done my best to try solve this alone - to no avail. I need to create one layer from three raster tiles that show presence/absence (0/1) of woody vegetation ...
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Why does @data@values slot for RasterLayer only contain logical(0) and not the actual values?

Trying to get to the bottom of why, when I read in a raster of NDVI, the @data@values slot does not contain the actual values until I set them manually. For example: NDVI <- ...
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39 views

Output Raster r.cost.full values

I am having troubles interpretating the output of r.cost.full. Currently i am working on a project comparing some arcgis tools with qgis tools (workflow and output). One of my examples is to make a ...
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81 views

Processing large amounts of Rasters in R

I have 6500 processed and clipped rasters that indicate snow levels on a daily basis in the northern hemisphere. I need to create a raster that represents a sum of the snow for the season. The winter ...
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27 views

Workflow for updating raster using polygons of different attributes

I require a specific output but it is proving difficult for me to work out a workflow. I have: 1) polygons of new housing developments (356, non overlapping) 2) a 25m raster of land cover I want ...
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34 views

Properly placing my raster over a shapefile on my map

I have an ASCII file that I converted to a raster. My heading on the ASCII file is: NCOLS 156 NROWS 720 XLLCORNER -170989.3011812 m YLLCORNER 1417628.464462 m CELLSIZE 1 ...
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67 views

Raster (Tiff) to KML for Google Earth Overlay - QGIS

I am trying to convert some raster files to KML in QGIS for overlay in Google Earth. They are really huge Tiff files as I processed them from 3 meter DEM datasets. I have been searching the web and ...
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43 views

Zonal Statistics for multiple rasters

I'm trying to create a timeseries of raster data (one layer per year) by polygon (Administrative regions). Is there any way in QGIS to perform Zonal Statistics for multiple years (without having to ...
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24 views

Mosaic rasterstacks based on minimum of certain layer?

I am trying to mosaic 42 remote sensing rasterstacks (with 250 bands) based on the criterion that in overlapping areas, the pixel should be taken that has the most nadir viewing angle Beside my ...
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30 views

Draw gridded lines inside a feature and generate random points

I have several vectors containing features that originated from a 30 x 30 m raster. I want to generate a grid of lines (fishnet) in all of the features that are more than 30 x 30m. As shown in the ...
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45 views

Combining multiple overlapping rasters - retain maximum value?

I have 40 overlapping raster grids (derived from flood modelling software) that I want to combine in such a way so as to retain only the maximum value in any of the given rasters at each grid ...
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62 views

Combine several rasters in QGIS

I have a problem combining several rasters into one big raster. Particular annoying is, that I had this problem once before and solved it, but I can't remember how. Unfortunately the other ...
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24 views

Unable to set raster surface resolution in ArcScene?

I have a 3-band subset of a Landsat image which I want to display in ArcScene (of ArcGIS version 10.2.1). The image is 30 meter resolution and I am draping it on a 25m resolution Aster DEM. But have ...
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28 views

'combine' more than 20 raster bands

I have overlapping polygon data that I would like to 'combine' in ArcGIS and I'm running up against the 20 band maximum for rasters. I'm interested in solutions using this basic method with Arc or ...
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67 views

Extracting multiple values of raster to polygons using ArcGIS for Desktop?

I was hoping I could get some help on how to extract information from a land use raster using polygons. I have a layer with 157 polygons and a land use raster with multiple land use categories for the ...
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92 views

ArcGIS 10.3 Build Raster Attribute Table fails for large rasters

I am looking at forest loss in Central and South America within protected and unprotected areas. So I have a binary raster (0 or 1) for forest in 2000 and another raster for forest in 2013. I want to ...
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42 views

How to clip a raster by extent using Processing from the Python console?

I want to clip a raster by extent in QGIS with the python console. Here is the description given in the documentation. You have to use the following input parameter: Input layer Nodata value ...
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30 views

Merging DEM files using PostGIS

I have several DEM files and I want to merge them to create a mosaic. I found the St_Union(raster) or St_MemUnion(raster) functions but I don't know how to use them. Are there any other solutions?
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101 views

Deleting polygon defined area from raster layer in ArcGIS for Desktop?

Which tool do I use in ArcGIS 10.1 for Desktop to exclude areas covered by vector polygon layers from a raster layer? I want to keep portions of the raster layers that exclude the portions covered ...
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64 views

Clipping a tiff image using another tiff image using python

I am working on a code to clip a raster with another raster. I have a forestcover.tiff image and i want to clip it by using other image clip.tiff which extend lies within it. I dont want to use arcpy ...
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polygonize some raster pixels based on their value in PostGIS

I need to extract and polygonize only those pixels of a raster that have a value (e.g.) greather than 2000.0 The reason is that I wish to do an operation like the following one (which is done only on ...
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71 views

Combining four shaded relief images into one single image using GIS overlay technique? [closed]

I have prepared four shaded relief images (hillshade) with four contrasting illumination directions 0°, 45°, 90° and 135°. I would like to combine four shaded relief images to produce one shaded ...
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When subtracting two raster with different cell sizes using raster math, what value is used for smaller cells?

After reading the answer to a similar question (What will happen if we subtract two raster with different cell size using Raster Calculator?), I am still left with a question. When the raster with ...
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23 views

Selecting all pixels above a given value in a raster in PostGIS

I have a raster with one band whose value represents the date of the occurrence (a sequential integer). This raster file gets updated regularly, and each time that happens, I need to run a process ...
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Averaging a big number of pixels within a several km radius

I work with ArcMap software and now I have the aim to average individual pixels within a several km radius from daily data for at least 1 month. So I made the grid with 4 km step (the step size is not ...
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37 views

Calculating where the Z values of two rasters intersect

I have several raster layers which are depth horizons, one of these horizons cross cuts the others and I would like to calculate the line along which this occurs. i.e. the line along which the Z value ...
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34 views

Merge raster tiles in PostGIS

I have several raster tiles that are adjacent and non-overlapping, so they form a mosaic. I am trying to merge two adjacent rasters using PostGIS but am getting an error that they do not have the same ...
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63 views

how to produce a RASTER representing X coordinates [duplicate]

In a journal article I have read that two rasters, representing X and Y coordinates respectively (see attached figure), have been entered as predictors in a GIS-based Logistic Regression for a given ...
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SRTM DEM and satellite DEM fusion

I have a SRTM DEM and a DEM derived from satellite (Cartosat). Both the DEMs are registered perfectly. Now I want to carry out a DEM 'fusion' process to derive a higher quality output DEM. I am not ...
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155 views

Does a SRTM DEM image show details such as fields?

I'm working through the QGIS Training Manual where I have a step to get ... ... raster images (SRTM DEM) which cover the region you have selected for your course. SRTM DEM can be ...
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23 views

Merging - Aggregation of Rasters

I'm a beginner in Java and a geomatics student. I'am using IntelliJ and I work in Java. I create two raster with the BufferedImage Java class. Raster1 Raster2 These images show for raster1 the ...
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27 views

Zonal statistics as table failed

I'm using ArcGIS 10 to perform "Zonal statistics as table" for my raster data (temperature). I would like to know that for each 50m level (for example, 0-50m), what is the average temperature. ...
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Transforming climate text data to raster in ArcGIS Desktop?

I have climate data in text files with no header in the format below from Udel's climate program. Each row has a lat, lon, and a temperature for each month (14 columns total) from 1900-2010. I need ...
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Remove Frame Border from USGS scanned images in ArcGIS

I have a couple of USGS scanned maps like I want to remove the frame border from these images so that I can use them in ArcGIS. Is there algorithm or python script that I can run to remove the ...
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Second order rectification display problems

I'm using GRASS 7.0 to geo-rectify oblique images taken from a fixed altitude and using RTK-GPS data as a GCP (as a vector file) for the process. The survey area is very small and flat, so I'm not ...
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Add feature data to raster to see where it occurs relative to depths in cross-section?

I have depth soundings in which I have used IDW to generate a continuous raster surface to display bottom contours. A hillshade was generated to display in addition to generation of a TIN and ...
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15 views

Select raster using in line variables

I am trying to select rasters based on an in line variable to insert such raster into raster calculator within model builder. However, when using the select data tool it does not allow for ...
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71 views

It's possible to use gdal_calc.py with an entire path of rasters?

I try to use gdal_calc.py to scale and transform a time-series of MODIS images. I've done that when i worked with a single image in the -A variable and a mask in -B, but i need to work with a ...
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Why are my block neighborhoods not square?

I am running block statistic on a couple of binary rasters. Everything seems to be working fine, but the blocks are not oriented with the rumb lines of my projection. They're tilted about 40 degrees ...
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28 views

Growing error from west to east when overlaying raster and shape

I am using a shape of Austria from gadm.org which I want to overlay with a netCDF file in R. As the netCDF has projected coordinates in EPSG:31287, I have reprojected the shape using FWtools and the ...
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45 views

Raster appears like polygon in Arcmap

I copied rasters across into my geodatabase for a client but when they open the raster dataset in ArcMap they appear in tiles as shown in the image below. When I drag and drop individual rasters over ...
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How to create a raster of equidistant points with distance in meters using QGIS?

I need a set of equidistant points (like a raster) each in a 1km distance to the next over a certain area, in my case Germany. I know the feature "regular points" in QGIS where I can do just that but ...
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How to best import a US Map Schematic?

I would like to use the following wiki US Map schematic as a background to my map work. (http://en.wikipedia.org/wiki/File:Blank_US_Map.svg) It is a .svg file, and GeoReferencer is unable to import ...
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74 views

How to interpolate raster to get finer resolution?

I am working with precipitation raster layer. It happens the raster data to be in a resolution of 0.25 degrees grid. How could I interpolate those pixels to have a better resolution, say, a resolution ...
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44 views

What can I do to reproject rasters without modifying the original values?

I downloaded a series of Landsat 8 Images and I will be using QGIS to process them. The projection of 2 of them are incorrect, so I used "Warp tool" in QGIS to change them. The resulting rasters DO ...
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38 views

Creating polygon layer from raster

I am using ArcGIS 10.2 in order to create soil management zones for farmers. when I use the raster to polygon tool it creates small triangles out of the polygons and jagged edges that are very ...