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On 12/16/22 19:19, Ulises Ibarra wrote:<br>
<blockquote type="cite"
cite="mid:CAP=Ak6g1b7x7DyBSU5Zn3Xa1VWY4gvAe6qdDHCB6gGP9rvEXGA@mail.gmail.com">
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<div>Hello everyone:</div>
<div>I have a question about the use of filters.litree. When I
run:</div>
<div><br>
</div>
<div>$ pdal pipeline ./litree_prueba.json</div>
<div><br>
</div>
<div>where de ./litree_prueba.json:<br>
</div>
<div><br>
</div>
<div>[<br>
"./input.las"<br>
{<br>
"type":"filters.hag_delaunay"<br>
},<br>
{<br>
"type":"filters.sort",<br>
"dimension":"HeightAboveGround",<br>
"order":"DESC"<br>
},<br>
{<br>
"type":"<span class="gmail-LI gmail-ng"><span
class="gmail-LI gmail-ng">filters.litree</span></span>",<br>
"min_points":50,<br>
"min_height":3.0,<br>
"radius":50.0<br>
},<br>
{<br>
"type":"writers.las",<br>
"filename":"./<a href="http://output.as"
moz-do-not-send="true">output.as</a>",<br>
"minor_version":4,<br>
"extra_dims":"all"<br>
}<br>
]</div>
<br>
<div>I get de following output: <br>
</div>
<div>"PDAL: All points collinear"</div>
<div><br>
</div>
<div>And the file "output.las" was never created.<br>
</div>
<div><br>
</div>
<span class="gmail-HwtZe" lang="en"><span class="gmail-jCAhz
gmail-ChMk0b"><span class="gmail-ryNqvb">Could you guide me
on what I'm doing wrong, please?</span></span></span><br>
<div><br>
</div>
<div>Thank you</div>
<div><br>
</div>
<div>Ulises<br>
</div>
<br>
</div>
</blockquote>
<br>
I've seen that error before when using hag_delaunay. It's
complaining it can't make triangles (delaunay triangulation) because
it thinks all of the input points fall on a line. I found that
sometimes hag_nn will work in these situations. It has been awhile
since I've hit that error (so I was using an older version of PDAL),
it was sporadic (only occurred on some input tiles) and I didn't
have time to track down the exact points that were causing it.<br>
<br>
I'm assuming (dangerous, I know) that PDAL is looking at some subset
of close points when it is constructing the triangulation and that
the error is stating that all points were collinear in one/some of
those subsets rather than saying that the entire point cloud is
collinear. However, if all of the source points are actually all
collinear, then that would explain it. <br>
<br>
If I remember right, this tended to happen on messy (noisy), very
dense (higher point density than reasonable given the precision of
the measurements) point clouds where I suspect that it may have been
possible for the point cloud to have areas where there were many
points at the same or nearly the same X,Y,Z. Another possibility
was the error being triggered by some odd (noise) points forming
nonsensical geometries. But as I said, I never did have time to
track down the root cause for sure.<br>
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