<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; color: rgb(0, 0, 0); font-size: 14px; font-family: Calibri, sans-serif;"><div>Michael,</div><div><br></div><div>VRTs are not spatial indexed. I wonder if you did a tileindex and created a vrt on that (as pdal wouldn't open a tileindex directly) if it would work a lot faster since a tileindex is spatially indexed.</div><div><br></div><div>Mike</div><div><br></div><div><div><div><div>-- </div><div>Michael Smith</div></div><div>Remote Sensing/GIS Center</div><div>US Army Corps of Engineers</div></div></div><div><br></div><span id="OLK_SRC_BODY_SECTION"><div style="font-family:Calibri; font-size:11pt; text-align:left; color:black; BORDER-BOTTOM: medium none; BORDER-LEFT: medium none; PADDING-BOTTOM: 0in; PADDING-LEFT: 0in; PADDING-RIGHT: 0in; BORDER-TOP: #b5c4df 1pt solid; BORDER-RIGHT: medium none; PADDING-TOP: 3pt"><span style="font-weight:bold">From: </span> pdal <<a href="mailto:pdal-bounces@lists.osgeo.org">pdal-bounces@lists.osgeo.org</a>> on behalf of Michael Rosen <<a href="mailto:michael.rosen@gmail.com">michael.rosen@gmail.com</a>><br><span style="font-weight:bold">Date: </span> Wednesday, October 11, 2017 at 12:48 PM<br><span style="font-weight:bold">To: </span> pdal <<a href="mailto:pdal@lists.osgeo.org">pdal@lists.osgeo.org</a>><br><span style="font-weight:bold">Subject: </span> [pdal] Colorization using a large VRT raster is slow, but using a small VRT raster is fast ... but why?<br></div><div><br></div><blockquote id="MAC_OUTLOOK_ATTRIBUTION_BLOCKQUOTE" style="BORDER-LEFT: #b5c4df 5 solid; PADDING:0 0 0 5; MARGIN:0 0 0 5;"><div dir="ltr"><br><div><br></div><div><div><br></div><div>I am using the filters.colorization with a .vrt built by gdalbuiltvrt. The raster dataset actually contains 2200 files which I believe are all correctly georeferenced and non-overlapping. Of those, there are only 19 that actually intersect the point cloud being colorized.</div><div><br></div><div>What I'm observing is that if I build the vrt with only the 19 files, the colorization runs in less than two minutes. However, if build the vrt with all of them, then it takes an unacceptably long time (I've not watched it finish but I'm keeping an eye on the open file handles ... it's finding right files but it's just moving through them really slowly).</div><div><br></div><div>I would expect that the VRT would be able to immediately provide the pixels from the right raster tile, making the number of tiles in the mosaic irrelevant. That's clearly not the case (does it not do some sort of indexing here?). Can anyone offer an explanation / fix? This is important because I actually have many LAS tiles to colorize and while all of them are contained in the bounds of the large mosaic, they each have a different extent.</div></div><div><br></div><div>I guess a work around would be to build small VRTs based on the geographic extent of each LAS tile. But how?</div></div>
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