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

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Raster alignment terminology?

I identify two types of raster alignment (assuming SRS is the same), but I am unsure of the correct terminology for these (or whether there is even a 'standard')? First, there is 'pixel alignment'; ...
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42 views

Creating a new raster layer based on mean of other raster layers, ignoring NA values in R

I am trying to create a new raster layer that is made up of the mean values from 7 other raster layers. I get results using overlay function mean: mean <- overlay(2000, 2001, 2002, 2003, 2004, ...
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21 views

plot rasters with the same line diagram

I have 6 raster files with continuous values for an area with the same extent. I have created a raster stack and I want to plot one line for each cell in the raster stack of my six rasters (like the ...
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30 views

clipping raster changes raster values?

I am working with BIOCLIM temperature/precipitation layers and I have noticed that when I clip the global raster down to a specific region, something happens and the raster value at a specific point ...
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3answers
39 views

Make all pixel in raster have the same value

I have a raster file with two categories: category 12 (total count=350) and category 14 (total county = 500). The attribute table looks like this: rowid Value Count 0 12 350 1 14 ...
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43 views

Displaying raster tiles from OSM data stored in a postgis server

I have been recently tasked with setting up a raster tile server that serves tiles from data pulled from a postgis store. I have managed to get a vector tile server up and running but I'm stuck on ...
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53 views

ArcPy reading a raster in a moving window?

I typically read large raster data using gdal and setting up a moving window of 256*256 pixels (for example). I recently had to do some processing using arcpy, so I did the same thing, using ...
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2answers
218 views

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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12 views

Dynamic polygons grid with specified area based on raster

I'm interested if anyone have idea how to automatically create (maybe in R?) dynamic grid of polygons with specified approx. area (for example around 20000 m2) based raster data or points with values ...
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31 views

Converting NAD 83 to WGS 84 in PostGIS

My question is about the best way to convert from NAD 83 to WGS 84 in PostGIS. I have a PostGIS DB containing National Elevation Data rasters. The rasters are in NAD 83 and I would like to convert ...
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2answers
56 views

How to clip several raster datasets with a mask?

I would like to clip many images (raster datasets, input) with a mask (shapefile), so I would concentrate only in the images I need for my study area. Is it possible to do with Arc GIS 10,3 ? I ...
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1answer
81 views

ArcGIS, How do I get smoother contours?

I am trying to get nice smooth contours using ArcGIS. I have already smoothed out the DEM using focal statistics, simplified and smoothed the contours. The current result looks like this, which is way ...
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48 views

Modelling soil texture using ArcGIS for Desktop?

I am doing a project for automated soil mapping using landsat TM imagery, I have 3 output rasters: one for sand percentage one for silt percentage and a third for clay percentage. How can I ...
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1answer
21 views

Mod function in GRASS GIS

What is the equal of ArcGIS Raster calculator "Mod" function (Finds the remainder of the first raster when divided by the second raster on a cell-by-cell basis.) in r. mapcalc in GRASS GIS?
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33 views

Substract 2 rasters with Raster Calculator in ArcObjects (VB.NET)

I'm having a hard time substracting 2 raster with ArcObjects sdk 10.1. I keep getting a nullreference exception at the gp.execute() method, but I can't figure out where the problem is, I recall ...
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33 views

Making virtual raster with average values [duplicate]

I'm working with many raster files. Is there a way to make virtual raster with average values in each pixel. (QGIS) It's for an NDVI index of summer months over 5 years.
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38 views

How to create ROI in Semi-Automatic Classification plugin QGIS

while trying to classify landsat images, I get the following problem: I click on the pixel I want to define a ROI, but the ROI polygon that the plugin creates appears in a different part of the image ...
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18 views

Raster data for maximum temperature

I am looking for raster data for maximum temperature, ideally on a state by state basis (US) to make the file sizes smaller. Data would need to be weekly or daily going back to at least 2010. I ...
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16 views

Using USGS Raster Split but getting errors

I am working on an issue where I am trying to split the 2011 nlcd .img file into counties. I am really just looking at the midwest, so I have state county shapefiles for IA, OH, MN, MO, IL, IN and WI. ...
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1answer
19 views

arcpy CSV file to raster attribute table?

Using TableToTable_conversion I can convert a CSV file to a table in a geodatabase, but how can make this table be the default attribute table for a raster in the geodatabase? I can't seem to find ...
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1answer
33 views

Align pixels from two rasters with different cell sizes

I have two rasters in a PostGIS database that I want to be able to compare. The first raster is at 5m pixel resolution and the second raster is at 30m pixel resolution and is on a different grid. How ...
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56 views

How to compute NDSI in ArcGIS for Desktop?

How do I compute a Normalized Difference Snow Index (NDSI) in ArcGIS's Raster Calculator? I have a Landsat 8 scene (hdf4 format) that contains derived surface reflectance band-by-band. Each band is a ...
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I need to create a function in R that processes rasters in esri grid format [duplicate]

I have loads of data (6500 files that I need to process and find yearly winter sums/averages/variance for. the format for my naming system is Syyyymmdd_rp. Each file is in the same file folder. I ...
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1answer
58 views

mosaic raster image non georeferenced

I have several jpeg2000 tiles non georeferenced and covering a certain area. I know in qgis you can mosaic image using the merge tool but I have done it only using georeferenced images, which is quite ...
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17 views

Creating ROIS in Semi Automatic Classification pluggin Qgis

I am trying to classify a Landsat 8 image using the semi-automatic classification plugin in QGIS 2.6. When trying to define ROIS, I select a pixel of of interest, but the polygon is created ...
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24 views

Compare two rasters in R with the cell value from one replacing the cell value from another

I am trying to create a single raster from two rasters. The first raster is made up of all 0 values and the second is made up of the current date value (formatted in days from 001 to 365). The problem ...
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60 views

How to calculate raster statistics for each band in qgis

i need to calculate raster statistics for RGBN (4 channels, multiband image) rasters in QGIS. In Arcgis if you use "calculate statistics" in Arcatalog, statistics are calculated for every image band. ...
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1answer
36 views

GlobCover 2009 dataset - importing legend and colormap values into R

Does anyone know how to import a legend for a raster layer (loaded as a .tif) into R such that it can be attached to the raster file itself and used in plotting? In this case, I am using the GLC2009 ...
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1answer
51 views

Compare two rasters with raster overlay and replace cell value with variable

I want to compare 2 rasters and when there is a change from 2 to 1 create a new raster that replaces the cell where the change has been detected with the change variable. ## Finds Cells that have ...
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1answer
38 views

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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1answer
23 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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22 views

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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33 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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1answer
41 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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35 views

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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1answer
31 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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1answer
80 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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1answer
26 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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1answer
33 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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56 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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37 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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1answer
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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1answer
39 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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1answer
60 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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2answers
22 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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27 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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2answers
57 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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67 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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1answer
36 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 ...