<div dir="ltr"><div dir="ltr"><div>Brad, hello:</div><div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">El mar, 17 ene 2023 a las 11:46, Bradley Chambers (<<a href="mailto:brad.chambers@gmail.com">brad.chambers@gmail.com</a>>) escribió:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr">Ulises,<div><br></div><div>What version of PDAL are you using? I think this method will always be fairly computationally complex, but we did have a nice speed-up with <a href="https://github.com/PDAL/PDAL/pull/3520" target="_blank">https://github.com/PDAL/PDAL/pull/3520</a> prior to the 2.4 PDAL release.</div></div></blockquote><div><br></div><div>pdal 2.4.3 (git-version: dcef18)<br> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div><br></div><div>Radius is distance used to select a dummy point. We default to 100 m, the same as is used in the paper. The purpose of the dummy point is to seed the class of points that will NOT belong to the tree currently being segmented.</div></div></blockquote><div><span class="gmail-HwtZe" lang="en"><span class="gmail-jCAhz gmail-ChMk0b"><span class="gmail-ryNqvb"><br></span></span></span></div><div><span class="gmail-HwtZe" lang="en"><span class="gmail-jCAhz gmail-ChMk0b"><span class="gmail-ryNqvb">Oh, I see that the paper says "We then insert a dummy point n0 that is far away (e.g., 100 m) from t0 into Ni."</span></span></span></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div><br></div><div>min_points is only used after the current tree has been clustered. If it's too small, it is skipped. Changing the min_points will not speed things up significantly.</div></div></blockquote><div> </div><div> <span class="gmail-HwtZe" lang="en"><span class="gmail-jCAhz gmail-ChMk0b"><span class="gmail-ryNqvb">Thanks for the explanation.</span></span></span></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div><br></div><div>I think the biggest opportunities for speeding computation would be to downsample the data prior to running the filter or to tile the data into smaller chunks. Whether that is a satisfactory solution for your workflow or not is really up to you.</div></div></blockquote><div><br></div><div>Please, l<span class="gmail-HwtZe" lang="en"><span class="gmail-jCAhz gmail-ChMk0b"><span class="gmail-ryNqvb">et me ask you a few questions:</span></span><span class="gmail-jCAhz"><span class="gmail-ryNqvb">
</span></span><span class="gmail-jCAhz gmail-ChMk0b"><span class="gmail-ryNqvb"><br></span></span></span></div><div><span class="gmail-HwtZe" lang="en"><span class="gmail-jCAhz gmail-ChMk0b"><span class="gmail-ryNqvb"><br></span></span></span></div><div><span class="gmail-HwtZe" lang="en"><span class="gmail-jCAhz gmail-ChMk0b"><span class="gmail-ryNqvb">1. Sampling a point inside a cube with a size of about 10 centimeters on each side, would this seem like a good level of subsampling to you?</span></span><span class="gmail-jCAhz"><span class="gmail-ryNqvb">
</span></span><span class="gmail-jCAhz gmail-ChMk0b"><span class="gmail-ryNqvb"><br></span></span></span></div><div><span class="gmail-HwtZe" lang="en"><span class="gmail-jCAhz gmail-ChMk0b"><span class="gmail-ryNqvb"><br></span></span></span></div><div><span class="gmail-HwtZe" lang="en"><span class="gmail-jCAhz gmail-ChMk0b"><span class="gmail-ryNqvb">2. I could cut the cloud of points into tiles, but would something serious happen if a tree is half in one tile and half in another?</span></span><span class="gmail-jCAhz"><span class="gmail-ryNqvb">
</span></span><span class="gmail-jCAhz gmail-ChMk0b"><span class="gmail-ryNqvb"><br></span></span></span></div><div><span class="gmail-HwtZe" lang="en"><span class="gmail-jCAhz gmail-ChMk0b"><span class="gmail-ryNqvb"><br></span></span></span></div><div><span class="gmail-HwtZe" lang="en"><span class="gmail-jCAhz gmail-ChMk0b"><span class="gmail-ryNqvb">3. Would each of the files for each tile be processed by batch processing?</span></span></span></div><div><span class="gmail-HwtZe" lang="en"><span class="gmail-jCAhz gmail-ChMk0b"><span class="gmail-ryNqvb"><br></span></span></span></div><div><span class="gmail-HwtZe" lang="en"><span class="gmail-jCAhz gmail-ChMk0b"><span class="gmail-ryNqvb">Thanks you very much<br></span></span></span></div><div><span class="gmail-HwtZe" lang="en"><span class="gmail-jCAhz gmail-ChMk0b"><span class="gmail-ryNqvb"><br></span></span></span></div><div><span class="gmail-HwtZe" lang="en"><span class="gmail-jCAhz gmail-ChMk0b"><span class="gmail-ryNqvb">Ulises<br></span></span></span></div><div><span class="gmail-HwtZe" lang="en"><span class="gmail-jCAhz gmail-ChMk0b"><span class="gmail-ryNqvb"><br></span></span></span></div><div><span class="gmail-HwtZe" lang="en"><span class="gmail-jCAhz gmail-ChMk0b"><span class="gmail-ryNqvb"></span></span></span></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div><br></div><div>Brad</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, Jan 16, 2023 at 4:13 PM Ulises Ibarra <<a href="mailto:ulisesmartinibarra@gmail.com" target="_blank">ulisesmartinibarra@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div><span lang="en"><span><span>Hello everyone:</span></span><span><span><br></span></span></span></div><div><span lang="en">I<span><span> have a few questions about the "litree" filter and the computation time.</span></span><span><span>
</span></span><span><span><br></span></span></span></div><div><span lang="en"><span><span></span></span></span></div><div><br></div><div><span lang="en"><span><span>After reading the paper: "2021-Li-PERS.pdf" which talks about the "litree" filter to segment trees, I thought I understood the mechanics of the "litree" filter, but most likely not.</span></span></span></div><div><span lang="en"><span><span><br></span></span></span></div><div><span lang="en"><span><span>When applying filters.litree to a file "L3_0+L3_1_sample_cada_4cm_suelo_dalaunay.las" with 2 million points, the processing time I have so far is a little over 72 hours.<br><br>My pipeline is the following:<br>{<br>"pipeline": <br>[<br> {<br> "type":"readers.las"<br> },<br> {<br> "type":"filters.litree",<br> "min_points":3000,<br> "min_height":3.0,<br> "radius":2.0<br> },<br> {<br> "type":"writers.las",<br> "minor_version":4,<br> "scale_x":"0.001",<br> "scale_y":"0.001",<br> "scale_z":"0.001",<br> "extra_dims":"all"<br> }<br>]<br>}<br><br>But I applied previous pipelines to identify where in the process I'm missing:<br><br>L3_0.las +L3_1.las<br> |<br>(filters.merge) (1)<br> |<br> L3_0+L3_1.las<br> |<br>(filters.sample) (2)<br> |<br> L3_0+L3_1_sample_cada_4cm.las<br> |<br>(filters.elm+filters.outlier+filters.smrf) (3)<br> |<br> L3_0+L3_1_sample_cada_4cm_suelo.las<br> |<br>(filters.hag_delaunay+filters.sort,dimension:HeihtAboveGround,order:DESC) (4)<br> |<br> L3_0+L3_1_sample_cada_4cm_suelo_dalaunay.las (Here is where I am)<br> |<br>(filteres.litree) (5)<br> |<br> L3_0+L3_1_sample_cada_4cm_suelo_dalaunay_litree.las (This is where I want to arrive)<br><br><b>Questions:</b><br><br>1. What could I be doing wrong?<br>2. Does the "radius" option refer to the "spacing threshold" they talk about in the paper? I set radios:2. May be I wil a get a <br>3. I set the value of min_points to 3000, thinking that any cluster of points better than that value would not be considered and would facilitate the computation. I'm wrong?<br><br><br>I hope you can help me. I feel really confused.</span></span></span></div><div><span lang="en"><span><span><br></span></span></span></div><div><span lang="en"><span><span>Tthak you.</span></span></span></div><div><span lang="en"><span><span><br></span></span></span></div><div><span lang="en"><span><span>Ulises M. Ibarra<br></span></span></span></div><div><span lang="en"><span><span><br></span></span></span></div><div><span lang="en"><span><span><br></span></span></span></div></div>
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