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

learn more… | top users | synonyms

3
votes
1answer
388 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 ...
5
votes
1answer
106 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
votes
1answer
504 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 ...
9
votes
2answers
804 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 ...
2
votes
2answers
2k 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 ...
8
votes
3answers
2k views

Determining statistical relationships between rasters using R vs ArcGIS Desktop?

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 ...
2
votes
0answers
214 views

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, ...
2
votes
3answers
1k views

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 ...
6
votes
3answers
7k views

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 ...
5
votes
4answers
1k 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 ...
5
votes
2answers
4k views

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 ...
3
votes
1answer
3k views

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 ...
3
votes
1answer
778 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 ...
9
votes
7answers
7k views

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.
12
votes
3answers
317 views

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 ...
-7
votes
3answers
1k views

Delivering map tiles in real-time without caching? [closed]

Is it possible to deliver map tiles quickly over the web without worrying about caching or seeding them? With raster map engines this is a problem because endering raster tiles is resource consuming. ...
6
votes
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 ...
14
votes
6answers
1k views

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 ...
1
vote
1answer
481 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 ...
25
votes
8answers
2k views

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 ...
16
votes
1answer
1k views

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 ...
16
votes
4answers
24k views

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 ...
1
vote
2answers
2k views

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,
5
votes
1answer
2k views

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 ...
5
votes
4answers
3k views

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.
4
votes
2answers
169 views

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 ...
6
votes
1answer
4k views

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.
7
votes
1answer
803 views

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 ...
2
votes
3answers
10k views

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 ...
8
votes
1answer
962 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 ...
4
votes
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 ...
1
vote
3answers
492 views

How to infinitely extend MapInfo grid layer?

We use a semitransparent grid layer (.mig file) to show 'hotspot' intensity in MapBasic (MapInfo. Because the grid is just a rectangle, this looks ugly. See for instance: . Now MapInfo allows grid ...
1
vote
1answer
549 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 ...
8
votes
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 ...
27
votes
7answers
3k 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 ...
8
votes
6answers
1k views

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 ...
5
votes
2answers
556 views

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 ...
6
votes
6answers
843 views

How can I convert a DEM into areas of “flatness”, with an arbitrary fill/cut to area ratio?

I want to find areas of relative "flatness" in a DEM. How can I find flat areas? I want to find a neighbourhood of contiguous cells that have an elevation variance that is within a certain ...
10
votes
7answers
6k views

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 ...
9
votes
3answers
3k views

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 ...