[OSGeo-Discuss] Image Management in an RDBMS...(was OS Spatial environment 'sizing')

Bruce.Bannerman at dpi.vic.gov.au Bruce.Bannerman at dpi.vic.gov.au
Thu Feb 21 19:19:24 EST 2008


IMO:


Hi Paul,


> All too often, the "benefits" touted for raster-in-database have 
> nothing to do with the database, and everything to do with the data 
> preparation tools that the vendor is including with their raster-in- 
> database solution.
> 
> To store rasters in a database, you need a set of tools that will (a) 
> chop the inputs into something small enough to fit on a database page 
> (tiling), (b) pyramid the source data up so you don't have to run re- 
> sampling operations on the fly, and (c) handle mosaicking operations 
> at the edges of source input files.


My preference is to use true image processing tools for raster 
manipulation. ERMapper, Erdas, Envi etc. There are also a number of Open 
Source tools that I've yet to explore.

wrt mosaicing, Erdas has a nice tool that incorporates aerotriangulation 
into the process.




> 
> Here's how to do all of this stuff without the database:
> 
> 
> > - store a relatively large amount imagery and utilise it as a single 
> > entity (e.g. a layer).
> 
> Use a web service to expose the data, such as WMS. You can view your 
> WMS in ArcMap, in Google Earth, in a web browser typing in a URL with 
> your toes.


WMS is showing a lot of promise, particularly with v1.3. I like the spec 
description of serving multispectral and multitemporal imagery from the 
one service, allowing the user to specify image time and bands to display.


> 
> Far more interoperable than raster-in-database client code, because it 
> is far simpler.
> 
> Using Mapserver, and a tile-indexed raster layer, you can publish a 
> seamless view of as many source files as you like.  (Chris Hodgson did 
> it for over 1000 source files, see http://mapserver.gis.umn.
> edu/community/conferences/MUM3/present/session2/hodgson/view)
>


We have a wealth of choices. 

What it comes down to is what is appropriate for your use case.


Thanks again,

Bruce




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