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11 votes
Accepted

Is there a major drawback of working with compressed LAZ vs. the uncompressed LAS?

Although I personally didn't feel a major difference in speed, apparently there IS a major increase of read and write time when using LAZ. Once again the lidR doc is an excellent source of information ...
Honeybear's user avatar
  • 2,464
9 votes

Creating photogrametric point cloud of an object from distributed photographs, here: Making accurate 3D model of building using UAV imagery?

I've done this before with success using the Photosynth Toolkit (http://www.visual-experiments.com/demos/photosynthtoolkit/), except instead of a drone I was hanging my head out of a small plane ...
crld's user avatar
  • 902
9 votes
Accepted

Editing LiDAR point cloud to remove noise/outliers present below and above ground?

You seem to have outliers: i) below the ground surface; ii) above the ground surface and vertically among other above ground real features; iii) above ground points with height greater than all ...
Andre Silva's user avatar
  • 10.3k
7 votes

Finding tree canopy width using PDAL?

First, for the answers proposed here, you probably do not want to use the ferry filter to push HeightAboveGround to Z, at least not prior to segmentation, as the act of normalizing heights involves ...
chambbj's user avatar
  • 108
7 votes
Accepted

Open .laz point clouds not available in QGIS 3.18

Could be wrong but you should reinstall QGIS 3.18 with the new installer. QGIS standalone installers on Windows are all based on OSGEO4W. At the moment, 2 OSGEO4W installers and only the new one ...
ThomasG77's user avatar
  • 31k
7 votes
Accepted

QGIS layer properties window oversized

You cannot scroll, because the buttons area is generally not in scrollable area. Since I use multiple screens which have different resolution, I frequently encounter this problem. Reduce the size by ...
Kadir Şahbaz's user avatar
6 votes

Cutting a hole out of a LAS file to omit that area?

PDAL supports a similar workflow, and it allows you to use any OGR-readable data source for the polygons. There is a tutorial on the PDAL website that describes how to do it. You can use Docker to ...
Howard Butler's user avatar
6 votes
Accepted

Finding the minimum spanning tree (MST)

Thanks to @spacedman I was able to solve it, using the code from the following post: gist.github.com/andrewxhill/13de0618d31893cdc4c5 I leave an example for those who need to reproduce it, once the ...
liap307's user avatar
  • 311
6 votes
Accepted

Get eigenvalues of large point cloud using lidR

Your question is complex but luckily has an answer. For future readers I copy here (parts of) the answer I gave you on SO but that is lost in the sea in absence of appropriated tags on SO. The ...
JRR's user avatar
  • 9,464
6 votes
Accepted

Calculating grid_metrics() in a loop, using column name within variable

That sounds overly complex and computationally inefficient. Why don't you compute all your metrics at once? mymetrics = function(f1,f2,f3) { list( avgf1 = mean(f1), sdf2 = sd(f1), avgf2 = ...
JRR's user avatar
  • 9,464
5 votes

Converting LiDAR point cloud to 3D mesh

Be aware that .las and .obj are not the same type of data, in which the first is composed by points, and the second is a type of surface. So, even processing the point cloud to output a surface it ...
Andre Silva's user avatar
  • 10.3k
5 votes
Accepted

Open source approach to classifying and removing LiDAR points from overlapping scans?

There are a couple of options. Depending on the area of MN where you're processing, the overlap areas of the data are classified, and you can use a PDAL filters.range to cull them out: pdal translate ...
Howard Butler's user avatar
5 votes
Accepted

How to filter point cloud by flightline in R?

This is not natively possible yet in lidR! But R is a programming language so you can write your own algorithm to achieve this task. If you can do that please share with the community it could be ...
JRR's user avatar
  • 9,464
5 votes

How to filter point cloud by flightline in R?

Update: Essentially, I am looking to remove the overlapping points so as to produce a homogeneous point cloud with no scanline overlaps. Besides thinning (Thinning large LiDAR point cloud?), if ...
Andre Silva's user avatar
  • 10.3k
5 votes

Georeferencing terrestrial LiDAR point cloud?

I've never used a Faro Focus but I do own a Leica C10 ScanStation and I imagine that the process of merging point clouds is similar for all terrestrial laser scanners. You generally need to have three ...
WhiteboxDev's user avatar
  • 11.1k
5 votes
Accepted

lidR: Save LAS files from a clip_roi list

clipped[i] returns a list with one element. You meant clipped[[i]] with double brackets. Also clipped[i] within paste0() is meaningless. Actually your use case is already covered by the package. ...
JRR's user avatar
  • 9,464
4 votes

Open source approach to classifying and removing LiDAR points from overlapping scans?

In the latest release of the open-source geoprocessing platform WhiteboxTools (v. 0.7) I just added a new tool called ClassifyOverlapPoints that classifies or filters LAS points in regions of ...
WhiteboxDev's user avatar
  • 11.1k
4 votes
Accepted

QGIS: Placing points relative to a specific coordinate

If you want to use a UTM-like projection that isn't a standard UTM zone, you can just specify your own Transverse Mercator coordinate system. Here's the PROJ.4 page on Transverse Mercator projections....
Logan Byers's user avatar
  • 2,859
4 votes

Removing noise from point cloud with lidR package

Short answer: No. And more specifically lidR is designed for ALS primarily, if ever I add a function for noise removal it will be for ALS first.
JRR's user avatar
  • 9,464
4 votes
Accepted

Creating buffer around points belonging to object using lidR

Assuming you have a shapefile with lines you can buffer the lines and clip the polygons library(lidR) library(sf) LASfile <- system.file("extdata", "Megaplot.laz", package=&...
JRR's user avatar
  • 9,464
4 votes

Is there a major drawback of working with compressed LAZ vs. the uncompressed LAS?

@Honeybear's answer is the right one, but with one important caveat – use LAS if you need to touch all of the points. If you don't need to touch all of the points, LAZ-based COPC can be much better. ...
Howard Butler's user avatar
4 votes
Accepted

Filter just the last return from a point cloud

Turns out you can use ReturnNumber = NumberOfReturns in the filter expression to obtain last returns only.
user92055's user avatar
  • 409
3 votes
Accepted

Georeferencing LIDAR scans in CloudCompare?

What is the format of your file? If you have a .ply, there is a new module of GRASS GIS that allows geo-referencing of points cloud in this format: v.ply.rectify. Here are the quick instructions: ...
SaraZanni's user avatar
  • 243
3 votes
Accepted

How can I create a 16bit PNG heightmap in QGIS?

I'm guessing that you're seeing quantization - the output comes out looking "terraced", like rice fields. If that's the case it's because you're outputting 8 bit png, which only has 256 possible ...
Steven Kay's user avatar
  • 20.5k
3 votes
Accepted

Finding tree canopy width using PDAL?

There are two additional options to identify trees from canopy height models. Both of these options will identify (mostly) trees, which you can then use as a mask to isolate buildings. find_trees in ...
Aaron's user avatar
  • 51.7k
3 votes
Accepted

Cutting a hole out of a LAS file to omit that area?

This is actually a multi-step workflow. First you need to create polygons or a raster mask of the areas you would like to clip/mask. Then either reclassify or clip the point cloud with the polygons. ...
Aaron's user avatar
  • 51.7k
3 votes
Accepted

Drone that generates a point cloud from photography

Probably they have made a structure from motion function. With the mosaic of several pictures around an object you can create its 3d model and get also the point cloud. Thats nothing too spectacular. ...
Matte's user avatar
  • 6,245
3 votes

Thinning large LiDAR point cloud?

You can use FUSION's ThinData command for this (Documentation p.130). ThinData is really handy because it allows you to thin point cloud data to a desired pulse density per square unit. From FUSION's ...
Aaron's user avatar
  • 51.7k
3 votes
Accepted

How to incorporate stdmetrics in gridmetrics function?

You can use the function stdmetrics inside your custom function like in the following example (using stdmetrics_z) myMetrics = function(z, i) { lidrmetrics = stdmetrics_z(z) mymetrics = list( ...
JRR's user avatar
  • 9,464
3 votes

Editing LiDAR point cloud to remove noise/outliers present below and above ground?

I'll recommend PDAL the point data abstratction library. I've had good success using PDAL for a similar filtering problem. I like PDAL because it is open source, provides Python support, and makes it ...
Charlie Parr's user avatar
  • 1,956

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