<html><body><div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:12pt"><div><span>But then we must preprocess the data before load it in QGIS</span></div><div><br></div><blockquote style="border-left: 2px solid rgb(16, 16, 255); margin-left: 5px; margin-top: 5px; padding-left: 5px;"> <div style="font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; font-size: 12pt;"> <div style="font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; font-size: 12pt;"> <div dir="ltr"> <hr size="1"> <font size="2" face="Arial"> <b><span style="font-weight:bold;">De:</span></b> Randal Hale <rjhale@northrivergeographic.com><br> <b><span style="font-weight: bold;">Para:</span></b> qgis-developer@lists.osgeo.org <br> <b><span style="font-weight: bold;">Enviado:</span></b> Miércoles 29 de enero de 2014
14:49<br> <b><span style="font-weight: bold;">Asunto:</span></b> Re: [Qgis-developer] Lidar data into QGIS<br> </font> </div> <div class="y_msg_container"><br>Would LASTools add anything to the conversation? I do believe they <br clear="none">re-order the file (but I've not used it).<br clear="none"><br clear="none"><br clear="none">-----------------<br clear="none">Randal Hale, GISP<br clear="none">North River Geographic Systems, Inc<br clear="none"><a shape="rect" href="http://www.northrivergeographic.com/" target="_blank">http://www.northrivergeographic.com</a><br clear="none">423.653.3611 <a shape="rect" ymailto="mailto:rjhale@northrivergeographic.com" href="mailto:rjhale@northrivergeographic.com">rjhale@northrivergeographic.com</a><br clear="none"><mailto:<a shape="rect" ymailto="mailto:rjhale@northrivergeographic.com" href="mailto:rjhale@northrivergeographic.com">rjhale@northrivergeographic.com</a>><br clear="none">twitter:rjhale<br
clear="none"><a shape="rect" href="http://about.me/rjhale" target="_blank">http://about.me/rjhale</a><br clear="none"><br clear="none">On 01/29/2014 08:25 AM, Jean-Roc Morreale wrote:<br clear="none">> Most lidar files are not spatially ordered so with a sequential read <br clear="none">> you will end up reading the whole file, it's like accessing a untiled <br clear="none">> unpyramided bigtiff : painful.<br clear="none">><br clear="none">> Le 2014-01-29 13:52, A Huarte a écrit :<br clear="none">>> I think but using a quadtree approach there is a problem, and it is<br clear="none">>> none other than the construction of the quadtree itself for so big<br clear="none">>> data.<br clear="none">>><br clear="none">>> IMHO I would use a specific provider (with a specific featureiterator)<br clear="none">>> reading sequentially the LAS file and discarding points before fetch<br clear="none">>> it to
renderer using the RectangleFilter of current FeatureRequest. It<br clear="none">>> avoid create many-many QgsFeature's that after are discarded in<br clear="none">>> renderer side.<br clear="none">>><br clear="none">>> I use this technique in a personal viewer, and after first read of<br clear="none">>> file (the file is cached in SO), the following drawings are quite<br clear="none">>> fast.<br clear="none">>><br clear="none">>> Alvaro<br clear="none">>><br clear="none">>>> -------------------------<br clear="none">>>> DE: Jean-Roc Morreale <<a shape="rect" ymailto="mailto:jr.morreale@enoreth.net" href="mailto:jr.morreale@enoreth.net">jr.morreale@enoreth.net</a>><br clear="none">>>> PARA: <a shape="rect" ymailto="mailto:qgis-developer@lists.osgeo.org" href="mailto:qgis-developer@lists.osgeo.org">qgis-developer@lists.osgeo.org</a><br clear="none">>>>
ENVIADO: Miércoles 29 de enero de 2014 13:32<br clear="none">>>> ASUNTO: Re: [Qgis-developer] Lidar data into QGIS<br clear="none">>>><br clear="none">>>> Can it performs fast enough to display hundred millions points or<br clear="none">>>> billions at once ? Does it leverage a quadtree approach ?<br clear="none">>>><br clear="none">>>> Le 2014-01-29 12:55, A Huarte a écrit :<br clear="none">>>>> yes, it can be implemented on renderer level (Martin Dobias<br clear="none">>>> propose<br clear="none">>>>> it) or on featureiterator level similar to current simplification<br clear="none">>>>> classes for line and polygons<br clear="none">>>>><br clear="none">>>>> I think it is pending for a test of performance<br clear="none">>>>> Best Regards<br clear="none">>>>> Alvaro<br clear="none">>>><br
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