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 ...
- 2,554
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 ...
- 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 ...
- 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 ...
- 31.2k
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 ...
- 78k
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 ...
- 4,106
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 ...
- 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 ...
- 9,654
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 = ...
- 9,654
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 ...
- 9,654
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 ...
- 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 ...
- 4,106
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 ...
- 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 ...
- 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. ...
- 9,654
4
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. ...
- 6,265
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 ...
- 11.1k
4
votes
Installing PgPointCloud extension for PostgreSQL on Ubuntu Bionic
I installed PDAL in anaconda environment, as Trevor suggested. Installation was successful, in Terminal whatever option that I type was worked, but when I connected with Postgres and tried to create ...
- 546
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....
- 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.
- 9,654
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=&...
- 9,654
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.
...
- 4,106
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.
- 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:
...
- 243
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(
...
- 9,654
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 ...
- 51.8k
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.
...
- 51.8k
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 ...
- 20.6k
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 ...
- 51.8k
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 ...
- 1,986
Only top scored, non community-wiki answers of a minimum length are eligible