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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.

-2
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0answers
17 views

Canopy Height Models subtraction using ArcGIS [on hold]

Good day all, I have two CHM .asc files from two different time periods created by using FUSION and Notepad++; I now want to calculate the canopy height difference for the models. Can anyone please ...
4
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1answer
23 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
35 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 ...
3
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2answers
72 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
91 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
111 views

How to rasterize ungridded XYZ (LiDAR) files?

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
37 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 ...
1
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0answers
16 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 ...
0
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1answer
37 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
53 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. ...
0
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1answer
45 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 ...
0
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3answers
61 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). ...
1
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0answers
51 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
39 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
63 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
95 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 ...
0
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0answers
74 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
78 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
85 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
133 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
61 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
53 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
116 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
175 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 ...
5
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1answer
213 views

Calculating shadow of trees with DEM in QGIS?

I have a DEM with a good precision (0,5 x 0,5 m/pix LiDAR) and I´m looking for the way to obtain a raster (or shapefile) with the shadow of the trees located in that place for a whole day (ideally ...
3
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1answer
105 views

Interpolating LiDAR intensity images in R?

I'd like to generate 0.5 m intensity images using lidR, but the resulting raster is full of pits. Here's a reproducible example: library(lidR) LASfile <- system.file("extdata", "MixedConifer.laz", ...
2
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1answer
111 views

Extracting projection from each LAS file in directory using ArcPy?

I am using ArcPy to automate the conversion of LAS files to Raster in ArcGIS. I'd like to extract the spatial reference from each LAS file along the way. Is it possible to do this using ArcPy tools?...
1
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0answers
30 views

Creating Left and Right Image pair to view with 3D goggles in stereo from DEM or Hillshade?

How does one create the stereo pair for viewing in a program such as StereoPhoto Maker? I have processed lidar that I'd like to turn into hillshades and then view in this kind of software, with 3D ...
1
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1answer
88 views

Resampling 0.7 m LiDAR (in raster already) to 10 m DEM in R?

How do I resample the 0.7 m LiDAR to 10 m DEM in R? What are the basic rules for checking the consistency?
3
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1answer
155 views

Calculating standard metrics in multiple LiDAR files with lidR 2.0

I am porting my existing code to lidR version 2.0 and would like someone to let me know if I am coding efficiently. My objective is: to process a directory of LAS files normalize las files calculate ...
3
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1answer
108 views

Getting source bounds when filtering LAS using PDAL?

I'm using PDAL to filter out non ground points to create a DTM along with a DSM also made through PDAL to create a Canopy Height Model using this method. My workflow looks like this. #!/bin/sh # ...
1
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1answer
61 views

How to identify understorey forest structure using airborne full waveform lidar data? [closed]

I am learning how to use lidar to study forest structures, but I cannot find any methodology on how to map understory trees. It is for a school project where I am mapping forest developmental phases ...
1
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1answer
42 views

Displaying pointcloud symbolized with RGB values in ArcMap?

I know that I can display a LAS dataset in ArcScene with RGB Symbology, but is there a way of doing this in the 3D View window in ArcMap? The LAS Dataset toolbar only has symbology for elevation, ...
2
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2answers
242 views

Using LAStools to repair headers for several LiDAR files?

So, I have 21 LiDAR files with incorrect information in their file headers. For example, when I import a single file into R using the following code, I get several warnings saying that there are no ...
1
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1answer
114 views

Converting LAS to TIFF using Arcpy - TIFFs writing out empty

I am using ArcPy to convert large batches of LAS files to GeoTIFF format. It seems like a lot of the data I have acquired from a particular source is giving me the same error: I am able to convert ...
1
vote
1answer
522 views

LAStools plugin in QGIS: ''The system cannot find the path specified."

I'm attempting to convert LAS files to a multipoint file using QGIS methods. I've found some documentation that suggests that v3.2 and up has LAStools available as a plugin so I downloaded the latest ...
1
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2answers
149 views

File header incorrectly reporting 0 point records in R?

I have a set of 10 LiDAR files that I'm attempting to retile and eventually use to create a Canopy Height model. I'm able to import them as a catalog, however when I go to retile my catalog, I get the ...
9
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3answers
351 views

Difference between LAStools, libLAS and PDAL?

After many readings, I'm still confused about the difference of use and the aims of the following tools for LiDAR data processing and manipulation: LAStools, libLAS, and PDAL. My understanding so far ...
1
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1answer
55 views

LiDAR data in GPS time, only in second. Missing week?

I have LiDAR data LiDAR Data captured, unsure what units or format this time field is in? which I learned that my LiDAR data is in GPS second, however I do not have a column of data which shows the ...
1
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1answer
45 views

LiDAR Data captured, unsure what units or format this time field is in?

I haven't been able to figure out or find out from searching around what units or format this time field is in my LiDAR data that was collected?
2
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0answers
55 views

Speckle on LiDAR data

Does LiDAR data suffer from the speckle noise like the SAR images and ultrasound cardiac images I'm used to? I think speckle noise is inherent to all active sensors, but I'm not sure for LiDAR ...
2
votes
1answer
64 views

Why a laz file warns: 'return number' greater than 'number of returns' in R?

Reading a laz file with the lidR package in R I have the following warning. What does it means? las = readLAS("chmp15.laz", filter = "-drop_z_below 0") #> Warning message: #> Invalid data: 8895 ...
5
votes
1answer
118 views

Choosing Topographic Wetness Index or Flow Accumulation raster?

What is the better raster to use qualitatively - Topographic Wetness Index or Flow Accumulation - to clearly see potential areas of surface flow/wetness across a landscape? As an example, what's "...
1
vote
1answer
53 views

Estimating building and vegetation volume with unclassified LiDAR datasets?

I'm trying to determine the ratio of building to vegetation change (i.e. how has the volume of built structures changed in proportion to the volume of vegetation) in a city over a period of five years....
3
votes
1answer
80 views

Interpreting cell coordinates from DEM?

I'm using Environment Agency DTM LiDAR data which I import into Mathematica in ASCII format to produce ground surface models, sections, etc. The process works fine, but I'm unclear whether the cell ...
4
votes
1answer
1k views

Accessing raw data from LAZ file in Python with Open Source software?

Is there anyway to access raw "LAZ" (not LAS) datasets in Python? I was trying to with ArcPy (I'd prefer not too), but it doesn't seem able to access LAZ. I'd prefer to work with the raw LAZ file and ...
1
vote
1answer
212 views

Splitting LAS file into smaller LAS files by shapefile geometry boundaries - using PDAL or Global Mapper. [duplicate]

I've looked up pdal documentation on how to clip LAS point cloud files:- https://pdal.io/workshop/exercises/analysis/clipping/clipping.html Referencing this example, and having a quick look around, ...
3
votes
1answer
212 views

Error in reading point cloud data (.las) in R?

I want to generate a DEM using a point cloud (.las) for which I tried reading it in R using rlas, lidR and rLiDAR : readLAS command and none of it seems to work. The LASfile is not being read at all....
2
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0answers
60 views

Parallel optimization for query over LiDAR dataset

I'm using PostGIS + pointcloud to store a huge dataset of LiDAR point (2M patches of 600points) I query this database to obtain the altimetic profile between two points. At the moment I have a huge ...
2
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1answer
415 views

Why ground model from point cloud in Global Mapper is inaccurate?

I have a LAS file that I assumed was based on LiDAR, but it is actually based on ADS (airborne digital sensor) imagery, according to the body that captured the data. I load the file in to Global ...