[Qgis-user] managing topomaps (need a better workflow)

[maning sambale]

Just tested with blue-marble sample.  Clearly impressed!
I'll try to compile the full mosaic to rasterlite.  Thanks!

On Mon, Aug 2, 2010 at 8:17 PM, maning sambale
<emmanuel.sambale at gmail.com> wrote:
> Stefan,
>
> Thanks for the pointers.  Reading the sample tutorial, Rasterlites
> looks very promising.  Since it is supported with gdal 1.7 I assume
> with QGIS 1.5 as well?
>
> The last message I found in dev said it isn't so.
> http://lists.osgeo.org/pipermail/qgis-developer/2010-June/010161.html
>
>
> On Mon, Aug 2, 2010 at 7:55 PM, Ziegler Stefan <Stefan.Ziegler at bd.so.ch> wrote:
>> Hi
>>
>> you probably want to try RasterLite:
>>
>> http://lists.osgeo.org/pipermail/qgis-developer/2010-July/010492.html
>>
>> I've never used it by myself.
>>
>>
>> mit freundlichem Gruss
>> Stefan Ziegler
>>
>>
>> ----- Originalnachricht -----
>> Von: "maning sambale" <emmanuel.sambale at gmail.com>
>> Gesendet: Mon, 2.8.2010 13:46
>> An: qgis-user <qgis-user at lists.osgeo.org>
>> Betreff: [Qgis-user] managing topomaps (need a better workflow)
>>
>> Hi,
>>
>> A brief of background.  We have thousands of scanned rectified
>> topomaps (mostly jpegs with jgw),  In order to view them
>> simultaneously, I use gdal VRT.  Although this approach allows me to
>> view the whole collection as a single data layer, loading them at
>> startup is incredibly slow and even during panning around the map
>> view.  Another issue is that vrt and rasters in general cannot be
>> loaded on the fly.
>>
>> Now, I need to use the several rasters in another projection.
>> Re-projecting the whole vrt mosaic  produces a very large GTif.
>>
>> I have this workaround.
>> 1. Open a qgis session with the vrt mosaic's projection and open the vrt mosaic.
>> 2. Zoom to area of interest and create a new tif file using raster
>> tools clipper (a gui for gdal_merge)
>> 3. Load the created tif file and reproject to the desired projection
>> using gdal_warp.
>> 4. Open a new QGIS session to load re-projected raster and other layers.
>>
>> I'm trying another option which is to re-project the vrt to another
>> vrt but this doesn't solve slow loading problem.  Re-projecting all
>> the individual tile can probably make it faster but you get the same
>> issue when you start working on another projection.
>>
>> I tried the WMS route which makes it easier to load specific area in
>> QGIS.  However,  sharing the raster layer to colleagues as a file (for
>> offline viewing) will go through the above steps.
>>
>> Any ideas in managing topomap collection?  I'm looking for a process
>> that would probably make it tedious as one time conversion, but
>> hopefully help us easily manage the data with the following use
>> scenarios:
>>  -  easily load the mosaic in different projections
>>  - select a bbox to clip and save to another raster format.
>>
>>
>>
>> --
>> cheers,
>> maning
>> ------------------------------------------------------
>> "Freedom is still the most radical idea of all" -N.Branden
>> wiki: http://esambale.wikispaces.com/
>> blog: http://epsg4253.wordpress.com/
>> ------------------------------------------------------
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>>
>
>
>
> --
> cheers,
> maning
> ------------------------------------------------------
> "Freedom is still the most radical idea of all" -N.Branden
> wiki: http://esambale.wikispaces.com/
> blog: http://epsg4253.wordpress.com/
> ------------------------------------------------------
>



-- 
cheers,
maning
------------------------------------------------------
"Freedom is still the most radical idea of all" -N.Branden
wiki: http://esambale.wikispaces.com/
blog: http://epsg4253.wordpress.com/
------------------------------------------------------