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Questions tagged [lidar]

LIDAR (Light Detection and Ranging or Laser Imaging, Detection and Ranging) is an active optical remote sensing technology that measures properties of scattered light to find range and/or other information of a distant target.

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2answers
60 views

Why are .las file sizes inflated when read using package 'lidR' via Rstudio?

I frequently use the package 'lidR' to do forest point cloud analysis and the package functions OK, just I noticed that every time I load in point clouds using Rstudio, the file sizes seem to be much ...
4
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1answer
32 views

Reading remote LASCatalog

Would it be possible to read in a LASCatalog from a URL or vector of URLs? It is not possible with the standard function, readLASCatalog(). The benefit would be that you don't need to download all ...
2
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1answer
84 views

Extracting (big) rocks from LiDAR data

I have a .las file and want to show the outline of the big rocks located in this area. So far I have done the following: Obtain a ground model from the .las file including the rocks. Calculate ...
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2answers
46 views

Problem processing Slovenian LiDAR DTM with GDAL (and QGIS): “too many stepY values” error

If I want to apply GDAL (version 2.2.3) on the LiDAR derived DTM (ASCII) from Slovenia (Link to Slovenian DTM below), I run into this error: gdalinfo input.asc ERROR 1: Ungridded dataset: At line ...
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1answer
62 views

CHM pitfree error : “Not a matrix”

I use the pitfree algorithm to create the CHM of 89 .LAS files. chm = grid_canopy(lasnorm, 0.5, pitfree(thresholds = c(0,2,5,10,15,20), subcircle = 0.2)) In the entire code, I go trough each files ...
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1answer
17 views

ArcGIS 10.X - DEM raster creation - Point to Raster vs. Terrain to Raster tools [closed]

I have a bunch of LiDAR data that I need to make a raster DEM & DSM from. From what I can gather my options are use the Point to Raster tool directly on the Multipoint feature or make a terrain ...
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0answers
12 views

How do I separate .lasd into point files of each class?

I am wanting to examine my DEM, DSM, and other models I'm generating from LiDAR data in the model wizard to find the method with the least amount of error. I want to separate the ground, and non-...
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0answers
15 views

Opening LIDAR DEM in QGIS with several .adf files

I have a LIDAR DEM dataset of a bay. What I got is a single folder with these files I found out that the w001001.adf is the one that contains all the raster data and that the dblbnd, hdr, prj.sta ...
2
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1answer
44 views

Small Scale LiDAR Analysis - Removing Extraneous Points

I am working with some LiDAR data, and have a problem I just cant seem to solve myself... The image below shows a point cloud representation of a utility pole. In this point cloud, there is the pole ...
3
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1answer
45 views

Classify point cloud from land cover raster values with lidR in R

I'm working with the R package lidR to process point clouds. I have a raster with 4 coarse land cover classes and the corresponding tile with the LiDAR data in las format (both in the same ...
2
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1answer
57 views

lasnormalize() is creating large negative values?

I am trying to generate a normalized height values for a catalog of las tiles. I first generated a dtm using: dtm = grid_terrain(ctg, knnidw(k=5)) Then, I normalize the values using: normalized = ...
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1answer
45 views

Classifying powerlines in LiDAR using ArcGIS Pro?

I have a LAS dataset that includes powerlines. The dataset is unclassified, but I have access to a feature class that includes the powerlines as lines. Is there a tool or method in ArcGIS Pro that ...
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0answers
23 views

Use Geotrellis to rasterize LiDAR data

How can I use Geotrellis (distributed format) to Rasterize LiDAR (or XYZ DATA ) in HDFS? I converted las file to spark RDD with the IQMULUS library and I want to use this RDD ( [x1,y1,z1] [x2,y2,z2] ....
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0answers
35 views

Calculate wall area from airborne LiDAR points

For a project at uni, I'm calculating several metrics of buildings from airborne LiDAR data. As is the nature of the data, there are little to no points of the walls of buildings. So my current ...
2
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1answer
33 views

Add classification with laspy

I need to add classification to create a LAS file. I used the code below but it was miss-classified. Is there any problem with the code? And what is the difference between: out.file classification ...
2
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0answers
58 views

Converting from .las to .ply and vice versa in Python? [closed]

I am trying to convert a .las/.laz file into .ply file, read the .ply file, do some processing on it and then convert it back to .las/.laz file. Is there any Python implementation for this? For ...
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0answers
39 views

Getting elevation heights from folder of thousands of shapefiles that apparently come from LiDAR?

I obtained a few folders purporting to come from LiDAR data taken of a U.S. county. The directories are set up like this. Data-folder - be_rasters -- 692500_725000 --- dblbnd.adf --- hdr.adf --- ...
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0answers
21 views

Adding RGB values from a .txt file to a .las file using laspy

I have a text file that has XYZ and RGB values in it. To convert it to .las format i use lfile = laspy.file.File(r"D:\las\tolas.las", mode='w',header=LasHeader(x_scale=0.01,y_scale=0.01,z_scale=0.01))...
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2answers
87 views

Seeking free public LIDAR data of road in LAS format?

I am currently working on LiDAR point cloud road marking extraction. Please help me to get relevant public dataset in LAS format? Sample data is as shown in the image below: Data without original ...
1
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1answer
77 views

Creating rasters from LiDAR using parameters other than elevation, intensity or class?

There are a number of tools out there that can create a raster from a LiDAR point cloud by interpolating elevation, intensity or class values, but these tools generally limit you to interpolating ...
1
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1answer
30 views

Converting LAS Dataset into a point feature class with x-y-z in TOC?

How can I convert a LAS data set (displayed as LAS point elevation in ArcGIS 10.5) into a point feature class with x-y-z information attached to it (or stored in the attribute table)? ArcGIS has the ...
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2answers
35 views

Further compression of LiDAR data besides LASZip

I am looking for a way to compress files other than LASZip that may make the files a bit more smaller, is there an efficient way to do this? Would zipping up a LAZ file further compress the file? Or ...
2
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1answer
41 views

lidR: no slot of name “header” for this object of class “LAScatalog” [duplicate]

edit: This question does share an answer with an existing question, and the problem is the same: lastrees() does not work on LAScatalogs. However, I'm going to leave this question up, because I think ...
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1answer
54 views

Change LIDAR classification of points inside polygons

I'm trying to create a pdal pipeline to adjust the classification values for all points inside polygons, but I can't seem to get it to work. The filters.range works correctly because the output file ...
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0answers
28 views

Combining/getting elevations from .asc files or .tiff with x and y locations [closed]

I am new to R and still getting to know the environment. I am doing a project in animal movement. I have x and y locations (plus IDs, dates, hours) in an Excel table, converted into .csv as well. I ...
1
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1answer
33 views

How does a LiDAR placed on a moving vehicle map the distances?

Please correct me if I'm wrong but LiDAR device shoots out multiple laser rays and maps the surroundings based on the time taken by the rays to reflect. But if the LiDAR is placed on a moving vehicle (...
2
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2answers
54 views

writeLAS writes corrupted file: 'end-of-file' after 10468 of 10474 points

I am seeing strange write behavior with lidR. The outputs from lidR are compressed to fall on a single line. I vaguely recall discussing this with JR before, but cannot recall a solution. #ok las0=...
4
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1answer
41 views

Using lidR to count number of pulse returns at different intervals?

I am trying to get the number of pulse at different height interval. I have used the lidR package to do this before with the code below but it seems that recent update in the package breaks my code. ...
2
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1answer
75 views

Configuring lidR catalog to overwrite raster output (with different extension)?

I have a small issue with configuring the lidR package for parametrizing the extracted raster files with grid_metrics() function. My question is how to set in the catalog options that: be able to ...
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2answers
127 views

Filtering above ground LiDAR points using a catalog in lidR?

I am analyzing LiDAR data collected two separate years- 2007 and 2015. My analysis is centered around changes in vegetation during this time period. The ultimate goal is to thin the data from the 2015 ...
4
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1answer
135 views

How to use lastrees on a catalog with a function requiring a CHM raster?

I'm still fairly new to using LiDAR data and R, so please let me know if this isn't clear. I am using the lidR package to segment individual trees over a large landscape. I have been using the ...
2
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2answers
326 views

Rasterizing ungridded XYZ (LiDAR) files? [closed]

I have a large set of ungridded xyz text files (LiDAR point cloud) and want to export them to any raster format (tiff, asc, gridded xyz...) for further GIS processing. The source: https://www....
0
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1answer
40 views

Creating DEM raster from ASCII .xyzi LiDAR [duplicate]

I was passed along some LiDAR data that is in .xyzi ASCII format. I am having trouble figuring out a way to build a TIN or DEM from this data. I brought it in using "ASCII 3D to feature", and ...
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0answers
21 views

Stacking lidar-derived height raster as ancillary data for segmentation in ENVI?

I get a a black and white image after following these steps. Does anyone know why I'm not getting a color aerial image beneath the mask? My setup consists of these steps: I mosaicked several NAIP ...
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1answer
41 views

Does lasfilterdecimate work when homogenizing by pulse?

In R lidR package, when I run lasfilterdecimate with the homogenize option excluding use_pulse = TRUE it works, but when I include use_pulse = TRUE, it does not work. For example, the code below ...
3
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1answer
65 views

lidR (rlas) writeLAS changes values from Classification attribute?

I have a point cloud with extra attributes: class : LAS (LASFˇ v1.4) point format : 6 memory : 2 Gb extent :7498400, 7499200, 5779500, 5780000 (xmin, xmax, ymin, ymax) coord. ref. ...
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1answer
68 views

Convert EPSG:2263 LiDAR data to EPSG:4326 to use with FSX

I have LiDAR (las) input files in EPSG:2263 (NAD83, NY state plane, feet_US) aquired from https://gis.ny.gov/elevation/ and want to convert those file to EPSG:4326 (WGS84) for use in MS Flight ...
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3answers
80 views

Problem with CRS metadata for UK Environment Agency LiDAR DSM tiles?

I have downloaded some LIDAR DSM composite tiles from https://environment.data.gov.uk/DefraDataDownload/?Mode=survey and opened them in QGIS 3.6 with project CRS set to OSGB 1936 (EPSG:27700). ...
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0answers
82 views

How to georeference point cloud data that was no spatial information?

I'm working on a project right now that the final goal is to compare two DTMs of a glacier surface from different years to visualize the change over time of the glacial surface. The first DTM was ...
2
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1answer
50 views

lidR lasaddextrabytes does not update header

My lidR version is 2.0.2 I am trying to add an extrabyte about treeID that I get from raster (lasmergespatial with vector is super slow). I have a problem with saving that extrabyte to LAS file. I ...
2
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1answer
74 views

GridMetrics output does not align with base DTM?

I am trying to derive grid metrics from LiDAR (.las) file using FUSION's GridMetrics tool. My problem is that the output raster from GridMetrics does not align with the base DTM used to run the tool. ...
4
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1answer
131 views

Configuring lidR catalog to save files with same filename?

I'm trying to learn how to use the options of catalog() within the lidR package in R. I'd like to save directly the processed files, for example, using grid_terrain() function over a catalog and save ...
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0answers
118 views

Timestamp mismatch in the data recorded by Vlp16 with Ublox-M8T

Currently, I am working on Velodyne vlp16, for which I recently added UbloxEVK-M8T support. The setup is working fine but when I record the data from VeloView, the GPS timestamp is showing incorrect ...
3
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1answer
82 views

Clipping a catalog with lasclipCircle returns “no point found within region of interest”

I'm trying to clip a catalog using lidR (v2.0.1) package. I've tried with lasclipCircle and lasclip. It gives me the error: no point in ROI, but when I'm viewing the shapefile using mapview (I've ...
4
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2answers
174 views

Removing noise from point cloud with lidR package

I have unclassified Terrestrial Laser Scanning (TLS) point cloud data which has some noise. Is there a function in the lidR package which can be used to remove noise?
3
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1answer
206 views

Exporting crown boundaries from tree segmentation in R?

I am using lidR package to segment my trees using lastrees directly from the points clouds. The function works fine, however I would like to export to vector file the canopy boundaries from ...
2
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0answers
76 views

Importing several LiDAR (.las) files in GRASS using v.in.lidar?

I'm building a DEM of a terrain in GRASS and have 48 LiDAR (.las) files. I know I can do this by using r.in.lidar (including the list of files as a .txt) and then r.fillnulls However, I want to ...
2
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1answer
62 views

Non-constant transformation of photogrammetric point clouds in R?

I have a process which attempts to register two forested point clouds using CloudCompare's Iterative Closest Point (ICP) algorithm. Often times, warping (especially in the vertical direction) occurs ...
3
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1answer
169 views

Filtering (lasfilter on) huge LiDAR dataset

My dataset is about 8.3 GB after loaded into R environment by using lidR package. Some points which have return number greater than number of returns need to be removed. With a small dataset, I ...
3
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1answer
287 views

Visualizing vertical profiles from LiDAR point clouds in R?

I would like to visualize the vertical profiles of different LiDAR point clouds in different forest types. I have extracted the z-values from the LiDAR files with lidR and put them in a dataframe with ...