[Qgis-developer] Lidar data into QGIS

[Randal Hale]

Would LASTools add anything to the conversation? I do believe they 
re-order the file (but I've not used it).


-----------------
Randal Hale, GISP
North River Geographic Systems, Inc
http://www.northrivergeographic.com
423.653.3611 rjhale at northrivergeographic.com
<mailto:rjhale at northrivergeographic.com>
twitter:rjhale
http://about.me/rjhale

On 01/29/2014 08:25 AM, Jean-Roc Morreale wrote:
> 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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>>
>>
>>
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