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

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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
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Watershed Delineation

I am trying to delineate just the catchment area of some lakes, and am wondering the correct way to do this. I already have a filled DEM, along with a flow direction and a flow accumulation raster. Is ...
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Creating a raster surface of overlaps from vector polygon shapefiles?

Basically what I'm trying to do (in ArcGIS 10) is to compare three vector files in order to create a 'comparison' raster layer. I tried using Data Comparison (under Data Management tools) but it ...
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2answers
776 views

Help with a Simple Code to Read a Metadata from a Raster File

Please help me with a python code to read metadata from a Raster file. Thanks
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0answers
646 views

two results of IDW in ArcMAP are different

i added the following points to ArcMAP using "Add XY Data". x,y,z 7,39,117 27,17,122 27,61,123 46,36,136 52,14,138 55,46,141 56,56,137 65,24,144 65,36,145 Changed raster output size in "options" ...
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1answer
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How to write binary ArcGRIDs outside of ArcGIS in linux?

I've been looking for a way to create\write binary formatted ArcGRID images in Linux without much luck. It seems the GDAL project only supports reading these files, but there is not write support. ...
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1answer
236 views

Creating color table file in PCI Geomatica

What is the simplest way to create a stand-alone color-table file in PCI Geomatica (PCT or STR)? I have some classified imagery with values ranging between 0-255 and I would like a way to ...
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1answer
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How do I get the count of NoData values in a raster?

I have created a raster in ArcGIS 10 with a large number of holes (NoData) in it. I want to fill the holes using something like the the following: rOut = arcpy.sa.Con(arcpy.sa.IsNull(rGround), ...
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How to get the elevation of the areas in a raster file from SRTM?

I have an SRTM elevation map. How do I get the elevation of each point in the map? I am using GRASS. Is there a GRASS script to do such?
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1answer
381 views

How to get the Flow or directional raster map using GRASS?

Aside from using r.fill.dir in GRASS, is this the script to produce the Flow or directional raster map? Is this the output for the script ...
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1answer
883 views

How to select a raster file that is under a polygon in a vector file?

I am using: v.db.select map=PHL_adm1 where=NAME_1='Bulacan' My vector map is over the raster map. I want to select the part of the raster map under the polygon(NAME_1='Bulacan') of a vector. Is it ...
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How to combine a vector and a raster file?

I want to combine a raster and a vector file. After combining, can I query on the resulting map to obtain a specific area? How?
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1answer
341 views

Converting dataset between coordinate systems

I'm working with NOAA's PRECipitation REConstruction over Land dataset, and am looking for an efficient way to sample the data by pixels on NASA's MODIS grid, using open source tools. The PRECL data ...
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1answer
104 views

Non-Research Transportation Raster applications

My experience with rasters is pretty basic. 99.95% of what I do involves vector and transportation modelling. In research, there are numerous transportation applications using rasters and imagery ...
3
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1answer
459 views

How to sensibly digitise this raster, scriptably, in ArcGIS

I have the raster below which I want to convert to a set of vector lines: As you can see, there are small breaks in the lines and some bits are double-width. I want to be able to reliably import ...
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2answers
612 views

Scriptable alternative to ArcScan (particularly vectorising lines within tolerances)

Sadly the answer to this question suggests that it is not possible to script ArcScan from within a python script. Therefore, does anyone know of any alternatives to ArcScan (either within ArcGIS, or ...
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2answers
1k views

Converting google map api coordinates into meters

How would I go about converting the results of my map bounding box into meters within javascript? For example, if I have the coordinates 51.52366625446907, -0.07467269897460938 decimal degrees, can I ...
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3answers
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Statistical relationships between rasters

I am trying to analyze how sets of rasters relate to each other using some statistical techniques. As, I don't have much experience using the spatial statistics tools in ArcGIS I was exporting my ...
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Process to gather raster cells under features

I need to gather individual raster cells underneath a feature in a featureclass as quickly as possible. It seems that most ArcObjects functions have problem with island polygons, multi-part polygons, ...
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3answers
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raster not displaying below certain scale

i've clipped a raster in 20 smaller images and i can zoom in until 1:150 in the original raster but, in the smaller ones, when i go below 1:4000, the workspace goes blank. i'm working with arcgis 9.3 ...
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3answers
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Clipping a raster using a polyline or polygon

I have a large raster created from values that cover the whole United States and Alaska which are both polygon and polyline features, this raster was caluclated using Spatial Analyst IDW ...
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4answers
706 views

Find the best path along raster

I've just posted a question to StackOverflow about the best way to go about finding the best path on the raster below (where whiter pixels are 'better'), but have realised that it might actually be ...
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2answers
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How do I use GDAL to convert from an arbitrary projection/datum into Equirectangular/WGS84?

I've been trying to use GDAL to convert from an arbitrary projection/datum into Equirectangular (aka Plate Caree, aka Equidistant Cylindrical, aka Geographic, aka Lat/Long) with WGS84 datum. All of ...
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How can I compute raster pixel width and height given raster bounds, row count, and column count?

Restated, how do I convert arc degrees to meters? For example, I have an elevation data raster that has the following metadata: WEST LONGITUDE=64.97798789° E NORTH LATITUDE=33.02003415° N EAST ...
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1answer
677 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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Extract raster values at points

How can I extract values from a raster by points. I prefer not in Arcgis. I prefer in Qgis or Mapwindow or other open source gis.
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What practices are available for modelling land suitability?

I currently use a "classic" raster based approach of dividing a study area into cells. All input layers are converted to rasters at the same cell resolution and given a suitability rating. A final ...
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Delivering map tiles in real-time without caching? [closed]

I am wondering how useful would you find to have a way to deliver map tiles quickly over the web without worrying about caching or seeding them? With raster map engines we know that this is a ...
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2answers
870 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 ...
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6answers
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Creating simple image from vector data

Can anyone suggest a quick (and preferably open source) way to create an image from a shapefile. For example, I have a shapefile containing parcel boundaries, I want to create a png file depicting ...
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1answer
452 views

How to Save a Raster or Polygon to ArcMap Table of Contents in C#?

Just as the title says, I want to save the Raster to the table of contents. I have a Raster displaying on the ArcMap IDisplay, but I can't figure out how to save it to the Table of Contents in ...
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What raster-based GIS systems really work?

Raster GISes like GRASS, ArcGIS/Spatial Analyst, and Idrisi can perform a rich set of data processing and analytical procedures loosely known as "map algebra." In today's computing environment it is ...
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Are there any general rules of thumb for selecting a transformation for Georeferencing?

There are several transformations that can be used when georeferencing a raster: 1st order Polynomial (affine) 2nd order Polynomial 3rd order Polynomial Spline... etc Are there any specific rules ...
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How do you decide what interpolation method to use for resampling raster data?

The question pretty much says it all; are there hard and fast rules about which interpolation methods are suited to each kind of raster data? Any Golden rules, rules of thumb? Good books or articles ...
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How can I access a raster dataset's attribute table?

I need to loop through the rows in the raster attribute table and add a date for each row. Thanks,
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1answer
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Coordinates of upper left corner in the world file?

According to Wikipedia and ESRI last two lines in the world file represent x and y coordinates of center of upper left pixel. Now, if I have a world file like this: 32.0 0.0 0.0 -32.0 691200.0 ...
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4answers
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Quantum GIS and ECW images?

How might I enable Quantum GIS to read ECW imagery? At the moment I'm mostly concerned about this on Ubuntu 10.4 amd64, but I also use WinXP & Win7.
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Unrestricted codec for creating raster files with interior pyramids files

I'm looking for a tool that will allow me to mosaic a collection of images into a file format with performance similar to MrSID or ECW, but without the licensing restrictions that those formats come ...
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1answer
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How to resample a batch of rasters using OGR/GDAL?

I'm looking for a function similar to GRASS r.resample. I have a folder full of TIF files and want to reduce their resolution ("scale them down") to reduce file size.
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How can I change the class of one pixel in a classified image?

I have a classified image (I did it in ERDAS) with six categories. There are some misclassified pixels (especially high-density urban category). Is there any way that I can choose one pixel and then ...
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3answers
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How to calculate Raster Area per Polygon?

In ArcMap, I have a raster file that contains 6 classes of landcover and a shapefile that is the census data (OA boundaries and their population). I want the area of each class in each OA? For ...
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1answer
703 views

How to apply a Majority filter in GRASS GIS?

I was wondering if someone could help me write a majority filter for GRASS GIS. I have this map (see below) which I need to run a filter over to make the red areas a bit more dominant. I know I can ...
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5answers
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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 ...
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1answer
425 views

How to bring georeferenced raster data into MAPublisher?

What is the appropriate method to import a georeferenced raster image into MAPublisher? I have been able to import other forms of map data, and created map views and such for them, but I am now ...
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4answers
1k views

Looking for a fast, open-source raster cost-distance function to use in code

I've been scouring the internet for a fast, open-source cost-distance function that I can embed inside my code. The functionality should basically work like the ArcGIS implementation where I can ...
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7answers
2k views

Work flow for georeferencing imagery using open source tools?

Does anyone have a recommendation for a work flow for georeferencing high resolution aerial photography using open source tools? Comparison of user friendliness and robustness between Quantum GIS ...
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seeking “Available Sky” implementations

I'm looking for implementations of an algorithm called "Available Sky". ArcGIS (Spatial Analyst or GRID) is preferred, but solutions in GDAL, SAGA GIS or others are perfectly acceptable. The ...
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Disaggregating aggregate GIS data using remote sensing

I haven't really done much with remote sensing imagery. I have census data for an area, and a TIFF raster image of the area. I'm sure this is possible, is there a simple way to disaggregate the ...
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How to get raster image as array in Python with ArcGIS

When starting to work with Python and ArcGIS 9.3, I assumed there would be a simple way to get a raster image into a Python array so that I can manipulate it before storing it back as another raster ...
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Make the nodata area of a resampled orthophoto overview white?

I have a set of orthophoto images which are each fully filled with data, but when placed together the coverage does not form a rectangle so there are nodata areas. In MapGuide, I need to be able to ...