[Mapserver-users] Just call me a newbie . . . multiple Raster LAYERs question {Scanned} {Scanned}

[blammo]

Ed McNierney wrote:

>Bob -
>
>I'm surprised that you report bad experiences with TIFF imagery.  In
>many respects, TIFF is the best uncompressed format to use for imagery.
>I've got about 21 terabytes of it, all running under MapServer.
>  
>
I don't have quite that much (yet) to distribute, only around 100 gig's 
right now, more coming in every daua though it seems :c)

>If you already have the data generated at multiple resolutions then I
>don't think the GDAL approach will help much.  It really is simply a
>different way of doing the same thing - prebuild the data at multiple
>resolutions and preselect the most appropriate source.
>  
>
I have multiple LAYERS (20 so far) that all use the same resoltuion 
scheming process, so it very easy to program against, especially for 
optimized applications.

>GDAL has the benefit of storing the entire image pyramid in one TIFF
>file, which makes file management and mapfile management easier, and it
>also automatically chooses the best source resolution for each request,
>so you don't need to calculate MINSCALE/MAXSCALE values.
>  
>
I had though about using MapServer at some point as a strictly Image 
generation engine with somew sort of storage scheme  (like the pyramid) 
to store things on the server side.  Still investigating things at this 
point,  all of the suggestions are being considered.

>The disadvantages are less flexibility in the resampling options (you
>can choose from several GDAL algorithms, but you have to choose one of
>them), inability to use externally-resampled images, files that are less
>suitable for redistribution to others because they're larger (may or may
>not be important), and less flexibility in adding/deleting resampled
>levels.
>  
>
I do like having the ability to forego MapServer entirely (many of our 
existing services only have a ~100 line PERL cgi to run the outputs 
with, with no (Map) server like piece in the way. All the tiles are 
pre-processed, and the CGI simply positions them in the browser 
appropriately with DHTML

>But either way, TIFF images should be an excellent choice for storing
>imagery.
>  
>
I also have some RASTER version of line work that I'm not convinced 
would work well as TIFF's Especially the transparent aspects and control 
options, like those available for PNGs for example.

Here is a simple interface (production I'm embarrassed to admit) that 
show a couple of these layers in action (without Mapserver at the moment):

http://pwultra5.ci.stpaul.mn.us/cgi-bin/drill/ped.02.pl?bbox=562820.444444444%2C152375.333333333%2C564332.444444444%2C153527.333333333&size=756%2C576&pick.x=542&pick.y=349

It's key benefit is that it is very, very easy to manage since it's just 
a set of files on the server, and a single CGI script that make the 
page.  It doesn't even have a zoom out function applied to it yet, but 
everyone likes the resource for reference lookups.  It's also tied into 
a couple of Address lookup routines as well.

Balancing something like this against learning MapServer (or any other 
service type package) is a tricky piece of the equation in my mind.  The 
advanced functions available with MapServer allow for a lot of end user 
enhancement in my mind.  That's why I'm moving many of these services 
over to MapServer.

bobb