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

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How to calculate the distance to the nearest water source?

I have a polygon hydro layer of my study area and am trying to calculate the distance to nearest water bodies from my site. Since my site are 2km*2km grids I am not sure how to calculate it? Whether ...
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1answer
49 views

Raster processing in ArcPy seems to “simplify”/“round” my resulting values

I'm working off a DEM and doing some raster algebra with it (real simple, add this decimal value, then divide by this value). The DEM in question is super high resolution LiDAR, that's both spatially ...
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19 views

How to iterate a raster calculator with a change in the input raster and in the values calculated? Than, how to put the results in a table?

What I do without iteration is the following: Change radiance to reflectance for band 3 with raster calculator Samething as #1 on band 4 (the values in the formula are different from #1) Calculate ...
2
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1answer
15 views

How to create multiple external overviews for a geotiff with gdal?

I want to have mutiple overview files (one for each overview level) for a GeoTiff, so I'm able to edit this files in a raster editor. How can this be done? Unfortunately, gdaladdo -ro creates only ...
3
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1answer
52 views

What is faster - a matrix, raster or a dataframe?

I have rasters over which I am performing mathematical operations. For example, where I need to calculate flow distance or distance between two grid points. What format is generally considered faster ...
2
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1answer
48 views

Displaying RGB raster on QGIS with no enhancement with Python Console?

I'm working with a RGB raster on QGIS 2.6.1, on a Windows 7 machine. I need to set the Contrast Enhancement option to No Enhancement with the Python Console (not through the Layer Properties ...
3
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1answer
233 views

Reading raster datasets from file geodatabase with FME?

I have a file geodatabase (10.2) with geodatabase feature classes as well as geodatabase raster datasets. I am using the Esri Geodb API reader in FME Desktop 2014 to read feature types from this ...
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0answers
40 views

Turning simple raster file into DEM?

I'm using QGIS LYON 2.12.1, and I want to turn a plain gray scale raster file (that I got from Google search) into a DEM. The aim is to apply the DEM (terrain models) function to the newly created ...
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2answers
6k views

Combining two adjacent raster datasets

I am trying to figure out how to combine two adjacent rasters into one raster using ArcMap 9.3.1. The problem I am having is that there appears to be a gap in the data. I would like to be able to ...
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1answer
13 views

Create image using raster photo layer with vector shapefile overlaid (landuse)

I am a beginner with QGIS. I have a raster aerial photo and wish to overlay a vector shapefile (I have already created) showing polygons of land use. Can this be done in QGIS, or do I need to use ...
3
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1answer
40 views

creating unique sets randomly distributed values for many defined areas…in a raster.

I have a large approximately circular study area comprised of 5000+ polygons which represent forest parcels. For each of these polygons I have up to 4 different species. These species occur in ...
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2answers
66 views

How can I calculate flow length in QGiS/GRASS?

I have these rasters: DEM Flow Direction Flow Accumulation I would like to calculate the flow distance of every pixel to the outlet of a basin. In Arc-GIS, I can use the flow length. But I don't ...
2
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1answer
219 views

Intersection of two Raster objects

I have two raster objects r1 (in grey and green) and r2 (in pink) that I want to intersect with R. I tried with the R function intersect from the raster package but it only intersect the extent of the ...
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1answer
43 views

How to find the cell location index of a raster using Lat long information?

I have a raster for which I want to find the Cell Location (Row, Col) if I have the Lat-long information. I know how to get the value of a particular cell using lat long. ...
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2answers
217 views

Really slow extraction from raster even after using crop?

I have a large raster file (245295396) cells and stacks of rasters having 4 layers each which lie in the extent of this large raster. To start with I am trying to get value from one stack (3 channels) ...
2
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1answer
193 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 ...
3
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2answers
467 views

Loading projection along with raster in R?

Why the operation myraster = raster("test.asc") does not load the associated projection file test.prj located in the same directory as test.asc? Does raster() need a specific argument? It seems ...
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1answer
44 views

R: extract values from raster stack and aggregate results

I'd like to extract values from a rasterstack, cell by cell, and create a list of the values: ext <- extent(0,100,0,100) r1 <- raster(nrows=100, ncols=100,ext) r1[] <- sample(seq(from = 1, ...
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0answers
21 views

How to create a numerical mask file with the elevation points of an area with QGIS

I'm using QGIS and I have to create a mask file (.txt) as an input for a hydrological model. The file should be a numerical grid map that represents the elevation points of a catchment area, like the ...
6
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2answers
684 views

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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2answers
3k views

Can ArcGIS Desktop stack layers?

I have 7 bands of Landsat and I would like to combine all layers into one layer. Can ArcMap 10 do this like Erdas software can?
3
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1answer
180 views

POSTGIS Raster - Merge polygon onto raster

I have two tables, SCHEDULE contains polygon geometries and RASTER contains raster tiles I want to take a polygon from the SCHEDULE table and overlay it on top of a set of RASTER tiles that intersect ...
4
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1answer
622 views

mosaic raster to file geodatabase yields missing raster sections

Since upgrading to ArcGIS 10.1 (SP 1) from 10.0, I've been encountering an issue when running the arcpy.MosaicToNewRaster_management() tool with output to a file geodatabase. I'm principally working ...
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2answers
524 views

QGIS Quickly switching overlapping raster images

I'm new to QGIS, and haven't used arcGIS in about 5 years, however I've just seen someone using arcGIS and was able to quickly switch between overlapping rasters when checking registration. The top ...
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1answer
175 views

ArcGIS error: Unable to save edits. Raster dataset already exists

When I edit my attribute table then try to save edits an error message appears on my screen: "Unable to save edits. Raster dataset already exist." Why does this error message appear? My table of ...
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1answer
89 views

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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87 views

display of raster in QGIS - cells are not rotated

when viewing rotated rasters in QGIS - the overall raster is rotated (as designed), though each grid cell is not. (the nodata value doesn't appear to pick up as the default in QGIS either - ...
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1answer
56 views

Importing raster from ArcMap to Adobe?

I am currently working with 3 data frames in ArcMap. I exported them to pdf then Adobe Illustrator. I noticed that 2 of the data frames that include rasters come up with striped layers on them (while ...
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2answers
34 views

get first levels of Raster Data

I have a huge raster tif file 40GB, when I use this file in ArcMap it is very slow, I want to use this file only for the first levels, so I don't care about resolution. I don't want a compression I ...
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28 views

Using arcpy to add several rasters

I need to do some raster/vector processing on some non-overlapping tiles. My python script needs to find the correct tiles and then extract the raster values and count them up. My script needs to be ...
3
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1answer
50 views

How to ‘invert’ or ‘reverse’ a vector cutline when gdalwarp'ing a raster?

I have a raster of North America and I'd like to remove the larger lakes from it, replacing them with the same no-data value as the original raster. So I downloaded Natural Earth's 10 meter lakes ...
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1answer
35 views

Export a raster file

I am exporting a raster file (tiff) in ArcMap as a png/pdf. But no matter how much I increase the dpi, the exported map looks smoothed version of the original images in my map. Any help please?
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1answer
28 views

How do I rename an out db POSTGIS raster

I used the following command to import a bunch of raster to postgis out-db style (only pointers to the rasters are stored in the database): raster2pgsql -s {srid} -c -R -I -C -F -t auto {file_name} ...
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19 views

GRASS: strange classification output and reject map from “i.maxlik”

I am trying to perform a supervised classification with "i.maxlik". I have three bands: 1) elevation (a dem); 2) reflectance (derived from Landsat ETM+ band4); 3) cumulative solar radiation (derived ...
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1answer
49 views

Clipping raster objects in PostGIS

I'm trying to cutting a raster object (from a PostGIS table) using a shapefile with reference, extracting raster data from a polygon area. My objective to work with the clipping raster into R. I'm ...
2
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1answer
359 views

Cannot get 2 raster files of same cell size to align ArcMap 10.2

I have two raster files that are the same cell size but I cannot get them to align properly. (I want the black to line up with the pink) When creating the black raster file (from using polyline to ...
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2answers
139 views

Where is World hillshade free download?

i need world hillshade with resolution about 1x1 km. Do you know where i can it download ?
2
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1answer
33 views

Error while executing v.rast.stats command in grass plugin in qgis

I have a vector polygon which I imported in grass. I also have a raster from which I have to extract the value. I ran v.rast.stats command in QGIS 2.12. The command was executed with error. The error ...
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0answers
47 views

Not all raster layers redraw

I'm running QGIS 2.12 and have the same issue on 2.8, but it is now worse in this latest version. The issue is that not underlying raster layers (satellite photos loaded in as .tif) are being ...
3
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1answer
82 views

R - Programmatically convert raster stack in data frame based on polygon extraction

Sorry for cross-posting. I also posted this question at the R-SIG-GEO discussion list, but since I wanted to get as much feedback as possible I decided to post it here too. I am trying to extract ...
7
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1answer
144 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 ...
3
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2answers
144 views

LiDAR intensity image from multiple flight lines?

I'm working with multiple raw las tiles, and I've used Fusion to create an intensity image, but it shows the flight line overlap (see below). Any idea how can I smooth the image so that the overlap is ...
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1answer
23 views

Inserting legends and co-ordinates in ndvi

I would like to know how to insert legends for the calculated ndvi in qgis. Also how to mark the co-ordinates in the ndvi calculated in qgis.
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260 views

Frequency of overlapping isochrones with map algebra in PostGIS

I have a table of polygons representing travel time isochrones on particular days. For each origin point, there are five isochrone geometries (stored in separate rows). For each origin point, I want ...
0
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1answer
31 views

Extracting raster values to polyline feature

I have a line overlaying a raster containing slope values. I would like to use the line to extract the slope values, and return to its attribute table an attribute containing percentage of slopes ...
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1answer
1k views

Extracting Raster Values by Polyline End Points using ArcGIS Desktop?

I am looking for a way to extract elevations of end points for line data in ArcMap 10.2. I have a road dataset that I want to use as a Network Dataset in Network Analyst. I want to be able to set the ...
3
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1answer
78 views

Extracting values from raster under line using GDAL?

How can I find the cells which lie on a straight line between two points? I.e. how can I find the indices of the cells (in grey) which are intersected by the line defined by the two points (in blue): ...
2
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1answer
36 views

Raster Calculator to extract elevation and slope conditions in ArcGIS for Desktop?

I've got a DEM ("ASTER_Nepal.tif") and a slope ("ASTER_Slope.tif") and am trying to create a new raster for elevation values between 2000 & 7000m and between 5 & 60 degree slope. I've tried to ...
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3answers
36 views

Standard deviation and average over 1000 images with random null values

I have a large collection of raster files that I would like to calculate the standard deviation over. The first issue is that ArcGIS cannot process over 1000 rasters via cell statistics, so I decided ...
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2answers
3k views

How to build an artificial 'dam' across a river?

I have a DEM. Created all files related to watershed including accumulation, direction, streams etc... I'm stuck creating a dam. I request you to please let me know how to build an artificial 'dam' ...