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

[maning sambale]

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/
------------------------------------------------------