[QGIS-Developer] Use of WebGL en Javascript (in Qt6 ?)

[Richard Duivenvoorde]

Hi Martin,

Thanks, but to be more clear:

- IIIF servers already serve out the maps in different resolutions in different number of 'tiles' per scale (like a tilecache without strict standardized tile definitions)
- the georef extension (creation and hosted by AllMaps) ARE georeferenced maps, as in: pixel -> lat lon coord and optionally the type of transformation

The WebGL path would just be the easiest, because than (I hoped) we could use their library to both fetch / choose scale AND warp the images...

But I will look into the way QGIS is doing this during georeferencing, maybe I can use the georeference info from the Allmaps-json to create the input for the gdalwarp and then create a VRT on the fly. Backside would be that I probably have to do this for the different z-levels.
But I will look into it.

Regards,

Richard


On 10/1/24 11:49, Martin Dobias wrote:
> Hi Richard
> 
> If I understand correctly, you could probably write a simple QGIS python plugin to do this as well, without any javascript/webgl magic needed - using gdalwarp to georeference the original maps and gdal's VRT to stitch them together. Maybe just with the downside that it would not work "on the fly", and the maps would need to be downloaded beforehand.
> 
> WebGL (or in our case its original desktop counterpart, OpenGL) usage in those maps is to make the map rendering faster - this is something that MapBox/MapLibre has been working on for quite some time. I would also like to have the QGIS' 2D canvas rendered with OpenGL (or DirectX / Metal / Vulkan) for faster map refreshes - but that's going to be a lot of work... maybe QGIS 5.0 :-)
> 
> Cheers
> Martin
> 
> 
> On Mon, Sep 30, 2024 at 8:41 PM Richard Duivenvoorde via QGIS-Developer <qgis-developer at lists.osgeo.org <mailto:qgis-developer at lists.osgeo.org>> wrote:
> 
>     Hi Devs,
> 
>     Anybody an idea about any possibilities to use WebGL and/or java/typescript in Qt6 (QGIS 4)?
> 
>     Context: in the archive/museum world old maps are often made available via de IIIF (triple-I-F) standard.
>     Which nowadays has a georef standard: https://iiif.io/api/extension/georef/ <https://iiif.io/api/extension/georef/>
> 
>     A dutch guy, created https://allmaps.org/ <https://allmaps.org/>
>     A site in which you can 'easily' georeference those old images AND which keeps hold of the GCP's created.
> 
>     So having a georeference IIF service/image it is easy to load it, georeferenced via the allmaps url (which is actually a json, referencing the IIIF service AND the GCP info:
> 
>     https://viewer.allmaps.org/?url=https%3A%2F%2Fannotations.allmaps.org%2Fmanifests%2Fc390af06ea724803 <https://viewer.allmaps.org/?url=https%3A%2F%2Fannotations.allmaps.org%2Fmanifests%2Fc390af06ea724803>
> 
>     All this is typescript/nodejs/javascript.
> 
>     Rendering/transformation is done life on a WebGL 'canvas'.
> 
>     In my ideal world, it would be possible to load the same url as above in QGIS, maybe do the realtime transformation in an 'offsite/buffered' WebGL canvas?
> 
>     But maybe I'm too eager :-)
> 
>     Regards,
> 
>     Richard Duivenvoorde
> 
> 
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