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I have created a set of tiled rasters as a super-overlay in Google Earth, and it performs remarkably well. Is there some way to load a super-overlay as a layer in QGIS? I am wondering if this could be an option to manage large numbers of rasters without setting up a WMS.

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Who are the target users of your project? Will they indeed have QGIS as a client? To my way of thinking, this is the reasoning for using GE, it has a wider/different set of users. – Willy Oct 4 '12 at 8:34
My target users are a small number of people who need access to 1:50,000 national topographical maps as a base layer for simple spatial operations (like area of a polygon). They currently use ArcView 3.2, and I am evaluating the possibility of using QGIS as a replacement. ArcView performs quite well when loading a large number of rasters as tiles, but in my experience QGIS can't handle it. Currently each workstation has the maps loaded, but I'm considering a server approach instead. – rudivonstaden Oct 4 '12 at 8:50
So maybe you are more concerned with the performance of the server and it's engine? I am not even a novice in this dept, but propose to you Postgis 2.0 with raster functionality. – Willy Oct 4 '12 at 10:42

2 Answers

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Did you checked OSSIMPlanet[1]. it uses OSSIM library and has a tiled loading mechanism. and it has a KML super overlay plugin[2]. But it has 3d rendering like Google Earth. I think performace will be much faster than QGIS

[1] http://trac.osgeo.org/ossim/wiki/OssimPlanet

[2] http://trac.osgeo.org/ossim/wiki/kmlsuperoverlayplugin

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thanks rashad, that looks like an interesting project. It seems it's only for viewing data though, and I would need to be able to do some spatial analysis on top of the base maps. – rudivonstaden Oct 4 '12 at 15:42
OSSIM developers are concentrated more on imagery. you can do RemoteSensing stuff like there are image chains, filters, sensor models etc. there is work done for adding vector support to OSSIM but not stable yet – rashad Oct 4 '12 at 16:51
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I figured out a way to do this using the QGIS OpenLayers Plugin and creating a TMS viewer for the tiles. Then I added the new viewer to the list of layers in the plugin (openlayers_plugin.py).

The viewer is not ideal. It doesn't refresh the image when zooming, only when panning, and could do with many improvements (not sure if this is a factor related to the viewer or the fact that it's using a different OpenLayers.js file), but it shows that SuperOverlay tiles can be read in QGIS.

My attempt at a viewer (modified from the openlayers.html file generated by gdal2tiles): https://github.com/rudivs/qgis-openlayers-plugin/blob/master/openlayers/html/tms_layer.html

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To get this to work I had to reproject into Google Mercator - I couldn't get it right with geodetic coordinates. – rudivonstaden Oct 5 '12 at 11:08

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