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

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808 views

Best way to manage large number of geoTiff rasters

I have around 2-3000 1-bit geoTiffs of size 11000x9400. Color 0 should be transparent, and QGis gets it wrong in the first place, so I used a .vrt file to set all the parameters in one single place. ...
7
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3answers
866 views

Creating raster or vector raster from DEM point file?

i have a point shape of 75.000 elevation points in a regular 5 m grid. We now want to create a polygon grid with the elevation points as "centroids". Unfortunately, all attempts to do so fail: I ...
7
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2answers
3k views

Modify raster layer display and symbology properties programmatically with arcpy or ArcObjects

I have over 1500 NITF files that I need to be able to modify the layer display and symbology of programmatically from within ArcMap. I need to set the properties outlined in red below: I've looked ...
6
votes
1answer
223 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 ...
6
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2answers
284 views

Wavelet vs Discrete compression for imagery

What is the main reasons to choose wavelet (jp2, sid, ecw) instead of discrete (JPEG) compression methods for raster data? Lets limit this question to aerial imagery and lossy compression. Why ...
6
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1answer
424 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. ...
6
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1answer
909 views

QGIS WKT Raster Plugin error, what does this mean?

I have been playing with the WKT Raster plugin. I have installed the WKT Raster experimental binaries in PostGIS successfully and followed the instructions in the read me to the letter. When i am in ...
6
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2answers
1k views

Moving raster to different mapset GRASS GIS

I have a raster DEM that I created in one mapset but I would like to copy it to another mapset for another purpose. Is this possible within GRASS or can I just copy some files over in the ...
5
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3answers
134 views

Create a Raster file out of a ASCII grid file?

im using a special system to do geomagnetic surveys. Its software let me output the information as image files, ASCII or in its own proprietary file format. Now i want to get its information in my GIS ...
5
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2answers
972 views

How to extract values from a raster according to Lat and long of the values?

having 12 files with 12 hdrs for one year: these files are raster (projected WGS84,lat long):https://echange-fichiers.inra.fr/get?k=rLSyoavrnifGyH5XrlO samples = 1440 lines ...
5
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1answer
2k views

How do I average a set of rasters?

How do I average a set of rasters? I have remotely sensed chlorophyll a rasters for several days and I need to get an average of the days represented as one raster layer. I've got QGIS 18.0 with the ...
5
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1answer
223 views

Getting ArcMap to display rasters properly first time

This is a very basic question, but as I've self-taught most of my GIS skills this is still a gap in my knowledge. When I load a .tif raster into ArcMap, most of the time it requires re-exporting to ...
5
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1answer
739 views

How to reproject a raster in QGIS?

I am a history teacher and I like to make my own maps (I can never find exactly what I want). I am using QGIS 1.8 and Natural Earth data. I want to reproject their cross-blended hypso rasters into ...
5
votes
1answer
998 views

Why do TIF loaded into PostGIS lose their colormap?

I have successfully loaded a TIF image (using raster2pgsql) into my PostGIS 2.0.1 database. I can load the raster image into QGIS and it displays in the correct space. However, it has lost all colour ...
5
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1answer
923 views

Raster data on PostGIS

I need to publish raster and vector data through GeoServer WMS service and I have already chosen PostGIS as datasource to keep vector data. Now I would like to know what is the best practice to work ...
5
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1answer
664 views

Raster processing with Python or Arc raster calculator

I have 4-band NAIP imagery that require the following processing steps: Convert to 8 bit unsigned B/W Reverse (note not inverse) the image, so that dark values appear light and light values appear ...
5
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1answer
1k views

How to rasterize SpatialPolygons in R?

I'm trying to extract the bathymetry values of my area of interest from a world bathymetry raster layer using the 'rasterize' function in the {sp} package. *Edits: I found the 'extract' function ...
5
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2answers
450 views

Adding noise to a raster

I want to add some fine-grained noise to a raster in an automated python process (i.e. I do not want to use Photoshop or GIMP). I looked at PIL, but unless I'm mistaken, it doesn't seem to have any ...
5
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3answers
746 views

Why is my mosaic of rasters a big, black rectangle?

I downloaded NED rasters from USGS, and I now want to mosaic all of the rasters into one. I used the Mosaic to New Raster tool, but the output is a big, black rectangle. Am I missing something? I feel ...
5
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1answer
2k views

Count number of unique raster pixels in polygon using ArcMap?

I have a polygon shapefile and I want to generate a table of a count for each pixel value in each polygon. My main goal is to find out what pixel is most abundant in each polygon. I am using ArcMap ...
4
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2answers
232 views

Converting shapefile to raster: Character attributes

I've got a shapefile that I would like to convert into a raster, but the trick is that the attribute I want a raster version of is character data. I'm familiar with geoprocessing using GDAL (in the ...
4
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1answer
822 views

How do I fill gaps in a raster to zero value cells?

I am trying to add some forest elevations to a DEM using ArcView. I have converted a polygon feature class of a forest into a raster with the same resolution as my DEM. Then I reclassed the forest ...
4
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1answer
671 views

How to sum or even perform more complex mathematical operations (multiply, add a constant, …) two GDAL grids?

I have two grids with same cell size, same starting position (top left) and same grid size. I want to sum the grids and create a sum grid as an result: e.g. grid A + grid B = grid C How can I ...
4
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5answers
864 views

Python loop Polygon to raster not working

I want to convert a large number of different shp polygons to raster in ArcGIS 10.1, using an existing field column "class" for the new raster classes. I am not very fluent in python but I thought ...
4
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1answer
1k views

Multiple Conditional Reclassification - ArcGIS

This is a question out of curiosity rather than a problem as I am not the most experienced with raster datasets and I wonder if there is a better solution to my current approach. I am trying create a ...
4
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2answers
487 views

How to fix a raster with wrong Eastings?

I get an error when trying to warp a tif file in QGIS: ERROR 1: Too many points (35721 out of 35721) failed to transform, unable to compute output bounds. I am using QGIS 1.7.0 Wroclaw with gdal ...
4
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1answer
254 views

How to sort entries in raster legend?

How do I reorder the Value field in a raster? There is no up or down button in it.
4
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2answers
468 views

What generation of the MrSID format is supported by ArcGIS 9.3?

This is probably old news to some, but I just learned that MrSID (.sid) files have different 'generations' of file formats - so there are MrSID Generation 2, Generation 3, and Generation 4 files. ...
4
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1answer
894 views

Can QGIS resample Rasters during display?

When I was using ArcGIS a user could resample a raster during the display (I think via layer properties under the display tab). This would smooth the appearance of the raster so it wouldn't appear ...
4
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5answers
3k views

Problems merging DEMs or other raster datasets? Clipping Raster dataset to vector line?

I have two DEMs that I am going create a hillshade from, and ultimately want one hillshade clipped to a county boundary. I am running into a couple problems, though. When I try to merge the two ...
3
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1answer
193 views

Getting Zonal Statistics of Overlapping Circles?

I have a Buildings (polygon) shp file and a DSM. what I wanted to do was to get the pixel values for all the vertices of those buildings, and find another pixel value just around those vertices (say ...
3
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2answers
259 views

The fastest way of generating tiles from raster?

I have some MODIS imagery 250m resolution covering a large area which I generate tiles from using Mapnik and generate_tiles.py script. I need to run this script every day with new satellite images, ...
3
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2answers
211 views

Calculating Z-scores in Arc

I am trying to take the natural log and then calculate z-scores on cell values in several composite band GRID rasters in Arc. I am not fluent in python and do not see a way to automate this within Arc ...
3
votes
2answers
182 views

How to do regression analysis out-of-memory on a set of large rasters in R?

I am trying to do a regression analysis on a set of large rasters (254,004,000 cells each). Ultimately, I want to run something like the following (or a bit more complex, but let's start simple!): ...
3
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1answer
2k views

creating a buffer in a raster layer

I've got a raster layer separated into 3 zones, representative of marine park zones. What i'm trying to do is make it so that where zone 1 is adjacent to zone 3, there is a "buffer" between them, of ...
3
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2answers
685 views

Majority filter (minimum mapping unit) in ArcGIS Desktop with larger window size?

I want to run the majority filter in ArcGIS Desktop with a window size of 4 or 5 i.e. greater than the default 3. Is it possible, or is there some other command (or tool) which might help me achieve ...
3
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1answer
1k views

How to convert jpg file to shapefile? [duplicate]

I am developing a GIS application like this: By now my steps are: I have got a jpg file, 5040 x 8179 dimension. In this map, the roads, rivers, towns etc. are marked. I am using .Net to develop ...
3
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1answer
578 views

Importing grib, grib2, netcdf to PostGIS

According to grib2 to raster? (grib2 -> raster2pgsql -> PostGIS 2.0 -> GeoServer), it seems like that grib2 can be treated as raster directly. Is it the so called "standard" way? How about ...
3
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1answer
236 views

shortest distance between a raster and another raster

i am using arcgis 10.1 i want to calculate the shortest distance between a raster and another raster. i have a bathymetric raster and an underlying fault plane raster. for each bathy raster cell, i ...
3
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1answer
320 views

An error in raster calculator in Arcgis

I wrote and ran this formula in raster calculator in ARCGIS. But the following error gets me into trouble. Does anyone have a suggestion to overcome this? Here is the formula I wrote and the error ...
3
votes
1answer
409 views

How to reproject a raster to Winkel Tripel projection?

I'm trying to project a raster map (in ASCII grid format) from longlat to the Winkel Tripel projection. But I'm running into errors, for instance gdalwarp won't accept the proj-string. $ gdalwarp ...
3
votes
1answer
2k views

ArcGIS 10 trouble displaying raster correctly

I think I've come across a Bug in ArcMap 10 in displaying rasters. This particular model comes from the USGS GAP Species dataset with metadata hosted here. I'd like to know if anyone else has ...
3
votes
1answer
4k views

Why can't I get MapServer to show a raster?

I am trying to use MapServer to display a raster image (png). That's it for now at least. However, I am having no luck. When I visit my map by using a link like: ...
3
votes
5answers
1k views

When a raster is clipped to a polygon with Python, why does it still take on the extent of the entire shapefile?

I am clipping a raster image to each polygon row in a shapefile in ArcMap 9.3 using the Clip tool (Data Management) in Python with Clipping Geometry set. While the clipped raster successfully depicts ...
3
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1answer
722 views

Good Java-Based Raster Libraries

Can anyone suggest a good, Java-based raster library? By good, I mean a library that can read common raster formats (ex. tif, img...etc) and save them to other image formats (ex. png). I say ...
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0answers
21 views

Geoserver : create a rasterized polygon / dynamic fill for polygons with features from database

I decided to post here because I couldn't find any answer to my problems on the internet. So I am using geoserver 2.7-SNAPSHOT, everything is working fine but I need to implement a new function or ...
2
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1answer
52 views

Build raster with multiple attributes based on 3 input rasters

I am trying to make a new raster based on three input rasters which have the same cell size and the grids align perfectly. I now want to construct a new raster, which for each cell, has three ...
2
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1answer
113 views

Georeferencing a raster using GDAL and Python

I want to georeference a raster using python and GDAL. My current approach is to call gdal_translate and gdalwarp using os.system and an ugly list of ground control points. I'd really like a way to do ...
2
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1answer
107 views

Dealing with raster: creating it in projected CRS and exporting it in geographic CRS

When creating a raster from a polygon (the CRS of the polygon is a geographic coordinate system), the raster is created in the projected coordinate reference system of the data frame, which is a ...
2
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1answer
151 views

How to find the projection of an image?

Instead of georeferencing the image and deforming it, I'm trying to find the projection used by the author of the image. I've got tens of these distribution maps to digitize. The idea is to avoid ...