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

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2
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2answers
218 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 ...
4
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1answer
436 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
204 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
1k 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: ...
5
votes
3answers
1k 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 ...
8
votes
1answer
328 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
1k 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
8
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2answers
1k 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
838 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
412 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
395 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 ...
-1
votes
1answer
106 views

How to locate 'symbols' by means of grid cells in MapInfo?

I am new to Mapinfo and GIS in general, but I have a new job in a company that works with maps and GPS and now I am being trained. My question, and I have looked a lot and I couldn't find anything, ...
3
votes
2answers
563 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
votes
4answers
966 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
votes
0answers
278 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 ...
2
votes
1answer
595 views

DTED/GeoTiff layer: Get elevation under mouse pointer

I have a simple desktop app with a map control. The map data that will be available to show will be either DTED files (Military Analyst's catalog / MADTEDLayer), or GeoTiffs (created by gdal). I want ...
4
votes
3answers
4k views

Convert ESRI Integer ASCII Grid to something useful

How could I convert a file(s) which is "DIGITAL Map data stored in ESRI ARCInfo Integer ASCII Grid format" into something the rest of us can use? i.e import into QGIS. The main file has no extension ...
0
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4answers
2k views

How to Clip a Shapefile of Circle features using a Raster using ArcGIS 10

I want to keep all the features in the shapefile that lie in the raster region and reject others. How do i do this? ------Adding More Details-------- Data to be Clipped: Is A Shapefile of 1 mile ...
6
votes
2answers
721 views

FOSS method to split raster into smaller chunks

I have a raster (USGS DEM actually) and I need to split it up into smaller chunks like the image below shows. That was accomplished in ArcGIS 10.0 using the Split Raster tool. I would like a FOSS ...
3
votes
1answer
668 views

How to handle time-based raster data in the ArcGIS Server JS API

The TimeSlider functionality in the ArcGIS Server JS API is great for working with time-based vector features - you can scroll forwards and backwards through time to see the vector features which ...
0
votes
1answer
271 views

Incorrect spatial extent for imported hdf image on ArcGIS

I imported an hdf image onto ArcGIS but I cannot make correct projection of it. Also, it does not have correct spatial extent (please see the enclosed figure, the small one is projected under WGS84). ...
3
votes
1answer
288 views

How to cope with imprecision in floating-point grids?

I have a floating point grid/raster and will want to make all values rounded to the nearest tenth. I have converted to integer (added 0.5 for rounding), but the final floating point output grid is ...
3
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2answers
2k views

ArcGIS: How to exclude outliers from raster?

I calculated terrain curvature from a DEM. The DEM I use is interpolated from point elevation data. Generally, the DEM seems to be good, but some artifacts from interpolation exist. Those artifacts ...
1
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1answer
413 views

How to eliminate small features in a grid?

(Update) My final goal is to take some logged point data (1 point about every 20 ft or so there are over 15,000 points) and interpolate that point data. Then I would like to convert the interpolated ...
5
votes
1answer
1k 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 ...
1
vote
1answer
131 views

Blank Vector Selection Dropdown in QGIS GRASS Plugin

I realise there are some issues which getting vectors into the GRASS module in QGIS, but is the behaviour i am getting expected? I have loaded the vector shapefile via GRASS, closed G and reopened ...
5
votes
2answers
3k views

Interpretation of ArcGIS Kernel Density legend parameters

In ArcMap 9.3 I've used Kernel Density to map various incidents, but the resulting shapefile doesn't display any units of measurement. Is there a good, not-to-technical source that would explain in ...
15
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5answers
852 views

Speed of various raster data formats

I'm having trouble locating any discussion or comparative benchmarking of different raster file formats (e.g., for use in data analysis in R). Does anybody have any insight into why particular formats ...
6
votes
2answers
2k views

How to extract road and building features from raster data?

I work with raster data and my task is to digitize a big image. This consumes much time just for digitizing roads and buildings! I'm looking for tools to simplify working on raster data to digitize ...
2
votes
1answer
2k views

Issue with Mosaic to New Raster tool

I am having a major issue with the Mosaic to New Raster tool when importing ASC files. It processes the first few files but not all of them. I thought it was a space issue and tried to split the input ...
1
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0answers
134 views

How to retrieve the value of a cell in RasterLite?

Just wanting to know the SQL statement needed to find out the pixel value for a location, when the raster is loaded into SpatialLite as a Raster? I loaded the Raster using rasterlite_load -d ...
1
vote
2answers
187 views

Finding zones with nodata in ArcGIS 9.3

I have a DEM raster with some small and large areas of NoData. I also have a raster defining zones (the zones consists of a rectangular grid). I want to create a new raster marking the zones where ...
2
votes
1answer
128 views

How to Separate out the disconnected regions of a raster into independent rasters using ArcGIS?

Please refer to the attached image. The overlay on the map shows a raster file with disconnected circles. I want to split each of those circles into independent rasters in one shot. Is that even ...
2
votes
1answer
946 views

Adding fields to raster attribute table

I have a raster attribute table associated with an IMAGINE .img raster that I build and open with: IGPUtilities utils = new GPUtilities(); IRasterDatasetEdit2 raster = (IRasterDatasetEdit2) ...
4
votes
2answers
1k views

How to find the area of raster values within polygon zones?

I'm using ArcGIS 9.3 and I just can't seem to get this right - I've tried tabulate areas, zonal stats, converting to polygons, etc. I'm missing something somewhere. I have a USGS impervious surface ...
6
votes
1answer
346 views

Normalizing and adding kernel density rasters

I have 4 years of road kill data for one road, though each year has a different sample time frame (i.e. May-June vs. April-October) and therefore each year has a different number of surveys and totals ...
6
votes
3answers
1k views

How to find the elevation differences between adjacent pixels in ArcGIS?

Is there a way to determine what the difference in elevation is between two adjacent pixels? I am using an SRTM DEM to map faults. I am using the vertical error (>16m) as a criterion for the ...
11
votes
5answers
2k views

How to scan large paper maps without a large format scanner?

Is there a way people have used to import a paper map as a raster without using a large format scanner. I do not want to cut my map. I'm wondering how much success people have gotten using things like ...
1
vote
1answer
213 views

How can GRASS export an .flt file?

I am using GRASS and connecting it to another application. The other application needs an FLT file of the raster map which I should export from GRASS. The other application only reads FLT files. Can ...
14
votes
4answers
2k views

Where can I find examples of fuzzy logic applications in ArcGIS?

The last ArcGIS version (10) includes two arctoolbox tools for fuzzy logic (Fuzzy Membership, and Fuzzy Overlay). Does anyone know where can I find some examples showing how they can be applied? ...
5
votes
1answer
834 views

How to display dynamic raster (lidar) data on a Web map?

I have some high quality LiDAR data. I need to process it dynamically, and update a field (not elevation field) depending on my input and elevation at that point. Once this is done, I need to display ...
1
vote
2answers
352 views

How to translate (reposition) a raster in Python?

I tried to use QGIS GeoReferencer to translate a raster layer, but somehow failed. It just goes to somewhere unexpected. Now I decide to do it myself, with python. I think some libraries like GDAL ...
4
votes
2answers
233 views

Finding Raster Overlap within a Directory

Here is the scenario: I have a directory with 100+ map projected, single band, rasters that weighs in a 40GB+. I have used ArcMap's built-in mosaicing tools to create a raster mosaic. I am using a ...
1
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0answers
134 views

How to get SplineWithBarriers to work in C#

I have been having fits trying to get SplineWithBarriers to work but to no avail. My environment: Windows 7 64 bit Visual Studio 2010 Team Edition ArcMap Release Version 10.0 Product Version: ...
8
votes
3answers
3k views

How to find the locations of the highest values in a raster?

Using ArcGIS 10, I have a raster where I would like to find the pixel with the maximum value in the raster and return its location (center of pixel) in decimal degrees. I would like to iterate through ...
4
votes
2answers
389 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. ...
5
votes
1answer
304 views

How to label raster cells in QGIS?

I try to show a small resolution raster file in the QGIS Print Manager tool. I would like to show a small label with each cell value (position - circa middle of each cell). How I can do it? Is there ...
4
votes
1answer
1k views

Filtering a raster by pixel cluster size in ArcGIS?

I have a raster image representing islands in a river (see image) created using the following process: 1) Clip a water surface DEM and watershed DEM by a bounding polygon (waters' edge). 2) Subtract ...
2
votes
1answer
199 views

Get Cell Value Webservice for ArcGIS Raster (LiDAR) without using ArcGIS

I want to expose the getCellValue function on Lidar Data, as a web service. But I don't have access to ArcGIS (server or desktop). What options do I have to fetch cell value, given lat lon, from a ...
3
votes
2answers
711 views

How do I only view selected rasters from a geodatabase raster catalog in ArcGIS 10.0

I am using a geodatabase raster catalog to hold raster files for multiple countries, mostly for the sake of organization. I don't actually have the need (often) to visualize or draw these all at once. ...