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

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11
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2k views

Random sampling of raster using R

Is there a straightforward way of randomly sampling a raster so that the output of the process is a raster? I'm using an example that I found on the r-sig-geo list and I have also tried the ...
11
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1answer
799 views

Method to shade or overlay a raster map to reflect time of day and ambient light

I have a daytime raster of my study area. I have 20+ counters in the study area that count "stuff" with a timestamp. Using PyEphem I determined the type of ambient light for each collected data ...
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0answers
166 views

Can I overlay layers in Dealul Piscului 1970 and WGS84 in QGIS?

I have a 10 Gb ECW file (mosaic of a whole county) that is in Oblique Stereographic projection with Datum: Dealul Piscului 1970. The problem was that no matter the Default CRS for new project was, ...
2
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1answer
369 views

ArcPy replaceDataSource to an SDE raster catalog error

New to Python! I'm trying to re-path a multitude of rasters currently the workspace is a folder, the intended workspace is a raster catalog in an SDE database - using the replaceDataSource method I'm ...
4
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2answers
502 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 ...
17
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3answers
761 views

Dealing with bridges and tunnels when modeling raster least cost paths?

I'm currently using ArcGIS 10 Spatial Analyst's Cost Path tool to model pedestrian routes. I have sidewalks, fences, buildings and a ton of pedestrian scale features, all combined into a cost surface ...
3
votes
2answers
384 views

Reading multiple grid data with Python and ModelBuilder

How can I read grid data (3 or 5 sources of grids) like slope, soil, cover, etc.? My goal is to build a simulator based on multiple grid data for harvesting decisions.
4
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2answers
2k views

Simplify Raster Contours ArcGIS 10

Does anybody know a way to simplify a number of contour polylines derived from a raster dataset? I need to generate a map that shows contour polylines at relatively small scale. With the contour ...
8
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2answers
500 views

How to add different sized rasters in GDAL so the result is only in the intersected region

I'm writing a Python method that adds two rasters and generates a single raster output. For reasons beyond my control, the extents of the input rasters are different, but they do overlap. Is it ...
1
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2answers
813 views

Tools/processes that avoid the need for raster to vector converstion?

A "brute force" method of solving GIS problems that involve acquiring values from raster cells and storing them on spatially overlapping vector features is to first convert the raster to a vector. The ...
3
votes
1answer
933 views

Workaround for Raster data input in ArcGIS Server Geoprocessing Service

UPDATE I have accomplished the Python script, but only tested in desktop environment, i.e. ArcMap. #Import ArcPy site package module import arcpy from arcpy import env from arcpy import Extent from ...
9
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4answers
7k views

How can I export raster data from Arcmap to an R *.grd file format?

I want to work with raster data in R, but I have problems exporting my raster dataset from ArcMap. By "export data"/GRID I get a file with an *.aux extension. What I need is *.grd. Can anybody help ...
4
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2answers
334 views

Reproject TM65 to OSGB in ArcGIS

I have a TIFF file in the TM65 (Transverse Mercator) projection, and want to convert it to the OSGB (British National Grid) projection. I'm trying to do this in ArcGIS using the Project Raster tool. ...
1
vote
1answer
381 views

How to Create and Rotate Raster Dataset using ArcObjects?

I'm following the "How to create a raster dataset" tutorial: http://help.arcgis.com/en/sdk/10.0/arcobjects_net/conceptualhelp/index.html#//000100000464000000 The questions are: 1) How can I create ...
2
votes
1answer
325 views

Bounding box argument ignored when displaying raster using mapserver

I am trying to display a raster image with Mapserver using different bbox arguments in a mapserv cgi request. I have been trying to specify different bbox arguments to "crop" the raster display, but ...
6
votes
1answer
4k views

How to import a raster into PostGIS?

I'm trying to follow the instructions here to load a raster into a PostGIS database: python raster2pgsql.py -s 4269 -I -r *.tif -F myschema.demelevation -o elev.sql I understand that I replace * ...
9
votes
2answers
834 views

GeoTIFFs made in GDAL don't have min/max range when loaded in Arc/QGIS

I'm creating some floating point rasters in GDAL with the GeoTIFF driver. When I load the resulting images into QGIS or Arc the default symbology puts the min at -3.40282e38 and max to 3.40282e38, so ...
5
votes
2answers
171 views

Distortion of equally sized world tiles

My question is related to this: http://stackoverflow.com/questions/7927863/location-data-format-for-adehabitat-package I have a relational database with 'world tiles'. Each tile has a side length of ...
3
votes
1answer
1k views

Conditional reclassification of a raster

I am attempting to do a conditional reclassification of an NLCD land-use raster. I specifically want to reclassify all developed areas (classifications 22,23,24) that are near a road (classification ...
2
votes
1answer
581 views

Simple band arithmetic on GDAL virtual rasters (VRT)

I want to calculate the difference of two bands. I have the individual bands stored somewhere, but I was thinking that maybe there's a way of producing a VRT file that is the result of this ...
3
votes
1answer
374 views

Splitting raster pixels by a polygon's edge?

I have a a polygon shapefile of different regions, and a raster grid of precip data. I want to take the polygon and add up all the raster precip data in each zone. I could use zonal statistics to do ...
4
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4answers
3k views

How to use ECW images with MapInfo?

I'm wondering if there is a way to use ECW images in MapInfo without having to 'register' the image as I bring it in? I mean, ECW images are already rectified (well the ones I use for GIS are anyway) ...
10
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1answer
425 views

How do I randomly alter a raster map of habitat types?

I have a raster of habitat types for a specific area in Scotland. I need to create future habitat scenarios with changes in habitat to assess the population viability of a bird species. For example, ...
2
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2answers
2k views

Converting ASCII grid/NTF to SRTM/DEM

I want to use the Ordnance Survey Land-Form Panorama product in some software called Maperitive, which can read custom SRTM DEM files. The data is provided in the following formats: DXF [Contours] ...
3
votes
1answer
224 views

How to calculate parameters for SQLServer raster to ESRI grid script?

My question is related to How to convert SQL Server Rasters to ASCII Grid? I would like to transform the data in the database into Esri grid format. I would like to write the program/script myself ...
1
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1answer
358 views

How to convert SQL Server Rasters to ASCII Grid?

I have 25km by 25km squares of the world in a relational database. Each square has coordinates for the top left and lower right corner as latitudes and longitudes. Each square also has an index ilat ...
9
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3answers
3k views

How to get hypsometric curve from elevation data?

I have my elevation data but cannot make an attribute table from it and so I'm not sure how to get any of that data into a table in order to make a hypsometric curve.
3
votes
1answer
818 views

Interpolate undulations for given points using a geoid model

I have two databases, the first one (F.tsj) contains gps points: coordinates and ellipsoid heights and the second one is simply a geoid model where every line stores latitude, longitude, and ...
3
votes
1answer
512 views

Georeferencing multiple rasters to World files

I've got exactly 56 tiffs to georeference. Each raster has its unique TFW world file. I'd like to automate this process. Each raster has it's unique name which is consistent with world file name (eg. ...
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2answers
2k views

How to set cell size for vector to raster conversion in QGIS GRASS plugin?

I'm converting a vector (loaded in GRASS plugin in QGIS (1.7.0.-wroclaw) and would like to convert this to a raster with a defined cell size. At the same time I need a value from the attribute tabel ...
4
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1answer
273 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.
3
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2answers
436 views

Need to clip raster based on field name in ArcGIS 9.3

Is there a way around for me to batch clip a raster using a field name to create output a raster layer ? Much like using Split tool but it is for a vector. How about that for the raster side ? Going ...
5
votes
3answers
514 views

Fastest way to test if raster contains data within a polygonal area

I am writing a python script for a geoprocessing tool in arcmap. I have a polygon in WGS 1984 Web Mercator (Auxiliary Sphere) and a raster grid, raster1, in WGS 1984. I reproject the polygon to ...
7
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1answer
188 views

Finding largest number of observations within a given radius

I have the following problem: Given the location of insured properties (say houses with fire insurance), i have to find the largest sum of insured values which fit into a 300m radius. Now, my first ...
4
votes
1answer
549 views

Can you use arcpy.RasterToNumPyArray() to Graph a Raster with matplotlib?

Can you use arcpy.RasterToNumPyArray() to Graph a Raster with matplotlib? I'm looking to graph a raster with X, Y, and Z values in a 3D bar graph. I just can't seem to translate the numpy array to ...
6
votes
1answer
207 views

What is the best raster format for large NoData areas?

Is there a good raster format for dealing with a large number of NoData cells? I do a lot of flood modeling and mapping, and recently I've been using rasters to show predicted flood depth and/or ...
3
votes
2answers
264 views

Hand fit curve and then apply to time series of rasters, make a map. How?

Maybe a data management problem, not too sure, but likely a challenge which someone has dealt with before. I have a time series of rasters. I can summarise the information by taking averages of each ...
3
votes
1answer
539 views

How does cost allocation work?

Why, when I use the cost allocation function of Spatial Analyst, is space not allocated in all input source locations (as shown in image below)? In particular, the input raster has 18 spots while the ...
3
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3answers
226 views

What FOSS GIS has the option to link attribute tables to rasters

In ArcGIS rasters can have attribute tables. What FOSS GIS offers a similar option?
13
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2answers
2k views

Good practice for generating contours from a DEM

We have just received a large set of DEMs at work and I would like to generate contours from them. The DEMs have a resolution of 1m and a size of 1kmx1km. Output from gdalinfo: Driver: ...
6
votes
2answers
2k views

Easily find centre point of a raster in ArcMap 10 document?

If I have, say, a rectangular and georeferenced raster file loaded in an ArcMap 10 document (.tiff w/ associated tfw), how do I easily find its centre point and store that point in a points vector ...
9
votes
1answer
429 views

How should I manage PostGIS Raster data with different projections?

I have a requirement to store and manage archaeological geophysics data that is collected as a rectangular array of samples -- a raster image. Each raster will usually 20x20 or 30x30 floating-point ...
1
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2answers
2k views

Merge single band and multi band color images

I do have 2 color images (orthophotomaps). One is only 1-band with color map and second is with 3-bands. How can I merge them with any FOSS tools or ArcGIS? Thanks a million
9
votes
2answers
2k views

PostGIS raster value of a lat/lon point

I have a tiff raster in my PostGIS 2.0 database. I want to get the value of the raster at a specified lat/lon point. I have: postgresql-9.1 postgis-2.0-svn with raster support a raster imported ...
5
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2answers
1k views

How to export a PostGIS raster to PNG?

I have a raster which is split into 30 tiles and I want to dump them all into PNGs. I've read the documentation http://postgis.net/docs/RT_ST_AsPNG.html but still don't know how to dump it well. If ...
7
votes
1answer
501 views

How to grid unevenly sampled categorical data?

I am looking for a method for gridding categorical data. I have extracted from nautical charts and field sheets a collection of points specifying the nature of the surface of the bottom of the ocean. ...
2
votes
1answer
488 views

Calculating beta-diversity w raster data [renamed]

Using ArcGIS 10, it is not possible to generate a raster attribute table for 32-bit float values. Instead, I have tried the RasterToNumPyArray method, which crashes since the file input raster is so ...
3
votes
2answers
729 views

What's a good way to display a custom raster basefile in Openlayers

I have a land cover raster that I'd like to display as part of an Openlayers based application. I'm able to load the raster directly as a PNG but my Openlayers application becomes VERY slow. I think ...
10
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4answers
1k views

Problems with NA values when reading .DEM file with R 'raster' package in Windows

I am trying to read a raster file in a .DEM format on windows using the 'raster' package in R. I get problems with NA values, when loading the data into R in Windows 7, but I do not have the problem ...
2
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0answers
305 views

Create custom pixel block size in ArcGIS 10?

I'm using the new IRawBlocks in ArcGIS 10 from the adopted sample in ArcGIS 10 SDK help and I want to create a custom sized pixel block that feeds me a block of values column by column instead of a ...