[Qgis-developer] Lidar data into QGIS

[Jean-Roc Morreale]

Most lidar files are not spatially ordered so with a sequential read you 
will end up reading the whole file, it's like accessing a untiled 
unpyramided bigtiff : painful.

Le 2014-01-29 13:52, A Huarte a écrit :
> I think but using a quadtree approach there is a problem, and it is
> none other than the construction of the quadtree itself for so big
> data.
> 
> IMHO I would use a specific provider (with a specific featureiterator)
> reading sequentially the LAS file and discarding points before fetch
> it to renderer using the RectangleFilter of current FeatureRequest. It
> avoid create many-many QgsFeature's that after are discarded in
> renderer side.
> 
> I use this technique in a personal viewer, and after first read of
> file (the file is cached in SO), the following drawings are quite
> fast.
> 
> Alvaro
> 
>> -------------------------
>> DE: Jean-Roc Morreale <jr.morreale at enoreth.net>
>> PARA: qgis-developer at lists.osgeo.org
>> ENVIADO: Miércoles 29 de enero de 2014 13:32
>> ASUNTO: Re: [Qgis-developer] Lidar data into QGIS
>> 
>> Can it performs fast enough to display hundred millions points or
>> billions at once ? Does it leverage a quadtree approach ?
>> 
>> Le 2014-01-29 12:55, A Huarte a écrit :
>>> yes, it can be implemented on renderer level (Martin Dobias
>> propose
>>> it) or on featureiterator level similar to current simplification
>>> classes for line and polygons
>>> 
>>> I think it is pending for a test of performance
>>> Best Regards
>>> Alvaro
>> 
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