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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21 views

Seeking GEDI data for specific region or country

Since GEDI data are published now, I am planning to download data that are over Bangladesh (the entire released data set is of 7GB). However, I suppose, the locations of the shots are references (i.e. ...
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18 views

Local Coordinates Transform to CRS string

I am fairly new to coordinate system transformation, so I am rather lost on the following case. I intend to process LIDAR data into LAS files and usually use global coordinates. this case uses local ...
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66 views

Difficulty using lasfilter (lidR) on an unclassified dataset

I have two .las datasets; one has been pre-processed but has limited spatial coverage and the other is the raw data with full coverage. My analysis only requires points between 10 and 40 m, hence I ...
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27 views

Clarification on LAS Overlap Flag

I am somewhat confused on the meaning of the Overlap flag which is present in las spec 1.4. The ASPRS LAS Version 1.4 Spec states: New to LAS 1.4 is the fourth flag, OVERLAP. It is frequently ...
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70 views

Viewing LiDAR data in QGIS or Google Earth

I'm determining tree heights from LiDAR point cloud data in Cloud Compare, but I'd like to import the data into QGIS or Google Earth. Simply saving the rasterized cloud as a .shp file in Cloud Compare ...
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49 views

Same LiDAR data but different results in ArcMap and eCognition

I have generated raster layers based on LiDAR Number of Returns in both ArcMap and eCognition but the results are quite different. I ArcMap I used LAS point to Statistics to Raster Tool, in the ...
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1answer
126 views

Unusual polygon shapes when using tree_hulls?

The following script uses lidR to segment trees and output tree hulls (i.e. polygons representing individual tree canopies). Input data are a directory of laz files and a catalog is used to manage the ...
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1answer
33 views

lidR - lasnormalize error handling

When normalizing a lasCatalog, the processing stops early with the following error: An error occurred when processing the chunk 22. Try to load this chunk with: chunk <- readRDS("/tmp/RtmpdcuTUO/...
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1answer
46 views

Find optimal chunk size using opt_chunk_size() in lidR catalog?

Is there a way to find the optimal chunk size using opt_chunk_size() when using a lidR catalog? I seem to always randomly choose integer values until the program quits throwing errors at me. For ...
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1answer
38 views

Remove buffer in catalog_apply()?

I am using catalog_apply() to normalize las points using lasnormalize() and segment individual trees using lastrees(). This is modified from the catalog_apply() lidR documentation (p.10): library(...
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1answer
65 views

How to deal with minus values on canopy height model?

I created a canopy height model (from lidar data) using lidR package and wanted to check it on Arcmap. I see there are minus values on canopy height models like -0.246219, -0.0302621. How can I deal ...
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23 views

Dynamic equal-interval raster styling for LiDAR data

I am looking for a way to create a colour map for raster (LiDAR) data in QGIS at equal-intervals (0.5 m, 1 m, 2m) which uses the same colour ramp whilst dynamically adjusting to the minimum and ...
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1answer
39 views

Extracting contours as shapefile from DTM (tif) in QGIS?

I am looking to convert a tif. file from the Scottish Remote Sensing Portal (Scottish LiDAR) into contours which can be used for a surface in civils 3D. I have tried this myself with a full DTM and a ...
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1answer
89 views

Assigning raster values to LiDAR point cloud in R?

I am trying to extract several point values for a set of liDAR data. I am starting with the DEM before I jump into the other more complicated values in my raster stack. Here is my code: library (...
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1answer
57 views

PDAL crashes when trying to filter noise points from outliers filter

I have a relatively simple PDAL pipeline being used to process a bunch of .laz files. { "type": "readers.las", "filename": "c:\\stuff\\10781001.laz" }, ...
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1answer
32 views

Evaluating elevation change between multiple LiDAR datasets

I am hoping to get some insight from others who are familiar with comparing multiple LiDAR surveys to one another. I have two LiDAR surveys with similar extents that I would like compare for elevation ...
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94 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 ...
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1answer
51 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 ...
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1answer
129 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
124 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
94 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
35 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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1answer
39 views

Separating LAS Dataset (.lasd) into point files of each class?

I am want 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-ground ...
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32 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 ...
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1answer
71 views

Isolating utility pole points from small scale LiDAR scene?

I am working with some LiDAR data, and have a problem I just can’t seem to solve myself... The image below shows a point cloud representation of a utility pole. In this point cloud, there is the pole ...
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1answer
72 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 ...
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1answer
68 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
73 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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33 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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62 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 ...
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1answer
70 views

Difference between classification methods 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 ...
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140 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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45 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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41 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
121 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 ...
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1answer
111 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 ...
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1answer
32 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
42 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 ...
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1answer
53 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
71 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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29 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 ...
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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 (...
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2answers
71 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=...
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1answer
48 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. ...
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1answer
119 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
271 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 ...
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1answer
189 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 ...
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2answers
673 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....
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1answer
54 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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29 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 ...