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

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69 views

Retrieve pixel value from raster layer in pyQGIS

I am trying to access the pixel data in all bands from a raster layer in QGIS from the Python Console. I have looked at several online resources including ...
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32 views

Issues with raster data on postgresql / error:Attempting to get pixel value with out of range raster coordinates

So here is the issue, i am trying to extract values from a big raster divided in 200 or so tiles and applying them to a selection. The points are startpoints, endpoints and midpoints from vector ...
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24 views

histogram of raster coordinates in R

I'm trying to generate an histogram of the y coordinates where raster values are 1. Mysteriously the following, different rasters, give me the same histogram. What could I be doing wrong? here are ...
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19 views

Map netncf-file with different years and save the different layers in shapefiles

Download from this website the following netncf-file: cru_ts3.23.1991.2000.pet.dat.nc.gz. This is a monthly raster with data from all over the world from january 1991 to december 2000 I am using ...
3
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1answer
39 views

How to order QGIS raster layer style?

I have single band raster files that I am trying to style using Singleband pseudocolour under the Layer Properties, Style settings, and a colour map textfile that I upload for styling. When I upload ...
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39 views

Clipping raster brick object in R

I have MODIS NDVI TIFF files for a year I want to first clip it with a irregular polygon (not by its extent only) of my study area and save it as a multi band raster in TIFF format The TIFF image are ...
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38 views

Cutting raster using ArcGIS for Desktop?

I would like to cut a raster file that I have. Here I attach a example of how it is original: And this is how I would like it would be. (I have cut the image on Paint): Can someone give me a ...
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34 views

Cut only a river of a raster file [duplicate]

I have one raster file which has a river that passes in a land. I want to "cut" only the river and save it to another raster file but I do not know how to do it. Can anyone give me any suggestion? ...
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2answers
56 views

What method does QGIS Merge Rasters tool use?

I am trying to merge rasters in QGIS and want to set a priority order for merging so that the values from the highest priority raster are used in overlap areas (the “FIRST” merge/mosaic method, I ...
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1answer
30 views

5x5 raster filter in ArcGIS?

Normally, I am using the 3x3 lowpass filter if I need to filter a DEM. However in one case, for better results in curvature calculations, I would like to do a 5x5 filtering. How is this possible in ...
2
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1answer
43 views

display historical map without georeferencing?

I have a historical map of Rome that was published as 46 separate sheets. I'd like to scan these sheets, mosaic them together, and display them as a single map. I've tried to georeference a few of the ...
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25 views

Adding rasters to mosaic dataset?

I'm working with an ArcSDE geodatabase v 10.0 in SQL Server 2008R2. I added more than a dozen of rasters w/o problem. Server: WIN 2008R2 12GB RAM SPACE: 1TB Created a mosaic dataset (empty) w/o ...
2
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1answer
47 views

What is the most efficient way to get a table or attribute table of a float raster?

I'm starting with a stretch point raster. Ultimately I want to get a mean value of values with larger zones and then rate the zonal mean stretching from 0-1 and output rank/zone to a table or layer ...
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1answer
40 views

PostGIS clipping raster with the same color band as the original raster

I am trying to clip a raster so that the clipped raster would have the same minimum and maximum values for the color band as the original raster. For example if i clip the raster with this command: ...
2
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37 views

QGIS: Merging raster files produces error

I'm trying to merge (Raster -> Miscellanous -> Merge) four raster files into one. Each file has same CRS and are saved as .tif files. Merge produces error: "The process crashed some time after ...
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21 views

Add information from a raster nc-file to a polygon shapefile

DATA Download from this website the following ZIP file: NUTS_2006_60M_SH.zip and save all the NUTS_RG_60M_2006 files. In what follows I refer to this as "NUTS3 regions". Download from this website ...
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1answer
24 views

Combine function on ArcGIS for Desktop?

I am trying to use the combine function on ArcGIS 10.3 for Desktop. I have two raster files that have the same values and I want to combine them in order to compute an accuracy assessment through ...
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2answers
94 views

Why am I getting two different outputs from Python and C++ using GDAL?

I am trying to gather information from a *.tif file using the GDAL libraries. When I open the *.tif file using both the Python API, and C++ API, I encouter two completely different answers. Here are ...
2
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1answer
40 views

What is a raster attribute table?

I've seen raster attribute tables mentioned in several places here at GIS.SE and at ESRI websites. However, I don't understand what is a raster attribute table (RAT). The resources I found so far ...
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3answers
120 views

ArcPy Script Tool takes 30min - Ideas to accelerate the (raster) process

I developed an arcpy script tool that takes as input multiple rasters, a criterion to select specific cells from the raster which are then intersected with a point shapefile. At the end a value is ...
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27 views

Control points in IAdjustXForm for georeferencing of raster (ArcObjects)

I am trying to create a georeferencing tool using ArcObjects in VB.Net. Though only a little text is available on this topic in forums as well as from ESRI; I found an esri article that states the use ...
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22 views

Using the extract function in raster package for R with polygons

I have a shape file that contains some polygons and an unprojected raster. I'd like to extract the cells within the polygons using R, so I use code like this: # Load my polygons MyPoly <- ...
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2answers
67 views

How to generate a buffer outside polygons having a given pixel value?

For example, I would like to build a 20-m buffer (represented in yellow in the image below) outside polygons having a value of 2 (represented in green) and to assign the value of 3 to buffer cells. ...
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17 views

Code to sift through many rasters and find rasters with errors using python [duplicate]

I would like a code to go through hundreds of rasters and print the names of the rasters that are problematic/don't work. I am trying to use the in cell statistics however I keep coming up with errors ...
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53 views

How can I align perfectly 4 topo sheets?

I have 4 topo sheets and i want then to align perfectly Would I have to georeference each image again? Or is there a more simple method?
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34 views

Is it valid to resample a raster from 1m to 3 feet?

I know that in general it is not a good idea to up-sample. I am curious if it would still be be a "bad idea" with a minor change like this from 1m resolution to 3 feet? Going to 3 feet would not ...
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22 views

Calculating the distance between points and parts of a underlying raster set

I need your help with a calculation of the distance between points (cities in this case) and forest (raster data). Is there a possibility to collate to every city the distance to the nearest forest ...
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19 views

How to unckeck automatically the “No Data Value” predefined on raster background on QGIS 2.14?

I'm trying to import a bunch of rasters, but there is a parameter predefined on the TIFFs, where says that No Data Value should be marked. But I need this unchecked. I opened the metadata, and found ...
2
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1answer
23 views

QGIS raster no data value changed to -inf when viewing at smaller scale

I have a raster with some no-data cells. I want to visualise raster values using a colour map and set the no data values to transparent. I am attempting to do this using the transparency tab in the ...
0
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3answers
74 views

Extracting impervious areas (buildings, rails, pavements) from LAS dataset [closed]

How to extract impervious areas (like buildings, rails, pavements etc.) from las dataset and receive it like a raster? I tried to do it with intensity, but there are many valids with vegetation. I ...
0
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1answer
34 views

Error message received when cropping raster with clipper

QGIS 2.10.1 Pisa Message -> Error: Computed -srcwin 8208 142185 0 0 has negative width and/or height. Tried with several different files and types of raster files [GeoTIFF, MrSis, ECW], the same ...
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2answers
42 views

How to Call ArcHydro Tools in Stand Alone Python Script

I am currently using ArcGIS ArcHydro tools to perform 'Catchment Polygon Processing'. However, it is proving time consuming to perform this for multiple rasters. How might a write a python script to ...
2
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1answer
71 views

Finding problematic rasters in large set of rasters using ArcPy?

Just wondering if anyone knows how to quickly find rasters that cause errors when I attempt to process them in cell statistics (as I am trying to sum them). I have many hundreds of rasters and don't ...
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1answer
67 views

Find NoData values inside a polygon area from a raster

I have a raster (representing a polygon in black) which contains NA values (represented by white pixels) that are located inside the polygon and outside the polygon. How can I get the index value ...
0
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1answer
32 views

Converting data from data frame into raster file using R?

I have the following data frame (long, lat, value) (all coordinates are within Colombia): Spoints: x y z 1 -75.67083 7.57916667 7.328901e-19 2 -74.59583 ...
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1answer
37 views

Finding and loading global population density raster data into R?

I am using the Bioclim dataset for a maxent project right now, but I want to add demographic predictors along with climatic ones. I have the 19 layer raster data from Bioclim and I'm hoping to use the ...
2
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1answer
33 views

Raster brightness, contrast, saturation in PyQGIS

I'm trying to find a way to change these properties (especially contrast and brightnes) and I've found a QgsBrightnessContrastFilter class, but I can't fugure out how to apply it to my raster layer. ...
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1answer
44 views

Crop Raster from using Polygon shapefile in R

I am trying to crop a raster by a polygon in R to the state of Sergipe-Brazil. My raster is a raster brick criated by 7 .tif files which are EVI (vegetation index) time series. Since the EVI archives ...
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25 views

Converting from ellipsoidal heights to orthometric heights (EGSA87)

I try to conver from ellipsoidal to orthometric heights with arithmetic function. In input raster 2 i put WGS84.img from \peodata\geoid folder.The results are not right. And now i have the question. ...
0
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1answer
45 views

Why do we georeference from the image to the shapefile (and not the other way around)? [closed]

Why do we georeference going FROM the image, TO the shapefile (and not the other way around)?
0
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1answer
32 views

How can I blend DEM rasters with GDAL?

I have several DEM rasters in different projections and at different resolutions. The rasters are not rectangular, but they have appropriate NoData values. They overlap enough that I should be able ...
0
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1answer
38 views

I want to have two raster data sets overlay

I am using ArcGIS 10.3 I have 2 raster datasets with different coordinate systems, but they are the same county (just different databases). When I add them to the same map layer they are far away ...
3
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1answer
83 views

Create polygons of the extents of a Raster in R

I want to create two polygons. One is of the rectangular extents of my raster. I know I can obtain the extent of the raster using r <- raster("band5.tif") e <- extent(r) but don't know how ...
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1answer
45 views

How to speed up raster2pgsql?

I'm trying to upload a 37 GB raster dataset to PostGIS. The raster is out-of-db (-R option), so the actual pixel values are not stored in PostGIS. I'm using this command: raster2pgsql -s 25833 -C -I ...
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28 views

Find Maximum value per month in rasterstack/brick and corresponding timestamp R

When dealing with raster images, I found the raster and rts packages in R to be very flexible for analysing my raster data unlike ArcGIS. In my learning efforts, I have had to do some ...
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1answer
36 views

Importing South African NGI OSM imagery xml file now unsupported by QGIS

Here in South Africa we at our very small company often make use of this simple xml file (downloadable from http://aerial.openstreetmap.org.za/aerial-osm-org-za-tiles.xml) to link to these imagery: ...
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1answer
38 views

smallest number of cells classified in a raster

I am using ArcGIS 10.3 and I ran con statement in the ModelBuilder within ArcGIS. I have an output raster (2m*2m) classified into four different classes. The raster has small pockets of 4 classes. I ...
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2answers
41 views

Append daily rasters to monthly lists in Python Arcpy

I'm trying to go over a folder of geotiff rasters where the last three digits of the raster name is the julian date and I want to append the correct days to monthly lists (Jan-Dec) and then run Cell ...
3
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1answer
135 views

Selecting multiple attributes, greater and less than

I am trying to select by attributes from a polygon shape file. I need to select areas with a temperature greater than 10 oC and lower than 15oC using gridcode but i can not seem to work out the ...
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1answer
37 views

How do I get rid of edge effects while using focal in R to smooth a raster?

I am trying to use R with the focal function from the raster package to smooth raster images. I am working with Radar images that have already been preprocessed. As part of that, some calculations ...