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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Processing a LiDAR image to be more detailed

I'm using ArcMap 10.8 to try and find old roadbeds. The DEM data I downloaded is very dark and shaded. You can't see anything at lower elevations. I have the hillshade effect turned on but you can't ...
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Using satellite data in ArcMap or ArcGIS Pro [closed]

I want to compare the volume of sediment on the beach (backshore) year to year using LiDAR (elevation) data in ArcMap or ArcGIS Pro. I was thinking of using satellite data to identify the average mean ...
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Calculating lidR::rumple_index for polygons using raster::extract

I have a raster (CHM) that I am using to calculate various vegetation metrics for a large set of polygons. See example below: veg_metrics = function(x, na.rm) c(mean = mean(x, na.rm=na.rm), min = min(...
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Optimizing and visualizing PDAL litree output

I have a pipeline that segments individual trees (called tree_seg.json): { "pipeline": [ { "type": "readers.las" }, { &...
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LASTools QGIS clip not working

As I am trying to clip the LiDAR data (.las) file from shapefile (.shp) I have used the lastools(lasclip) to clip the .las file from area of interest that is shapefile from Qgis plugin but it didn't ...
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Crop a large point cloud with GeoJSON defining the geometries of sub point cloud

I have a large point cloud (a city model) and would like to get the point clouds of every building in the city. I already have the GeoJSON file with the geometries of every single building in the city....
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Normalizing point cloud with LAStools is not working

I am using LAStools to normalize point cloud, however I still find some inaccuracies. I use these command lines to do the work: C:\las2las.exe -i originalLas.las -rescale 0.01 0.01 0.01 -auto_reoffset ...
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LAS2DEM QGIS No Results

When I try use LAS2DEM in QGIS, the results are an empty file: I have followed all setup instructions with the LAStools zip folder (in a C:\ with no spaces or special characters in the path, and set ...
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Rescale and reoffset in a for loop

I am looking for a way to run a loop to rescale and reoffset multiples laz files. I've tried with: path <- "D:/LIDAR/UNCINATA/2020_VALDELINARES/LAZ/" files <- list.files(path=path, ...
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Does LiDAR tend to georeference better than photogrammetry?

I noticed whenever I get a photogrammetry dataset, the products (like DTM, DSM) are always misaligned from satellite imagery of the same area by a few metres. Today I received a LiDAR dataset and they ...
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PDAL: filters.litree, how do I get the tree ID's?

Trying to get a hang of PDAL and to use the filters.litree to identify trees from a .laz dataset. My end goal would be to generate polygons outlining each individual tree (if possible). I've run this ...
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How do I create a LAS file coverage grid in QGIS?

I need to take a folder of .las files and create a coverage grid overview with an attribute for each las tile's file name within each polygon record, each polygon being the rectangle of that las file'...
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How do I convert .las files into usable .raw files for Unity?

From my research, it appears that the only 2 forms of geographical data that Unity will accept to create terrain are a png heightmap or a raw heightmap. Raw heightmaps are preferable as they can have ...
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Error with lidR::normalize_height

I am making a code for my master's thesis, in a part of the code I seek to obtain the normalization of the DSM of some municipalities of Galicia. The LiDAR files used come from the CNIG, they are the ...
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Does changing the Vertical Coordinate System of a LAS file changes the actual height/elevation values?

I would like to know should/does the original height values get updated if I change the vertical coordinate system. I already have the las dataset in WGS 1984 Now, I used the Extract LAS ...
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Generate topographical index from a digital surface model (DSM) to generate a flood susceptibility map [closed]

I'm performing a random forest model to generate a flood susceptibility map, I have LiDAR data from the study area where I generated Digital Surface Model (DSM) and Digital Terrain Model (DTM) raster ...
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LiDAR derived streams - map scale

Historically, streams were defined by the map scale. For example, for a map with a scale of 1:24,000 would mean that the streams identified on that map would be 1:24,000 streams. With streams that are ...
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Extract LAS: LAS Dataset Statistics

I am using the 3DEP LiDAR products to create a DEM for an area in the Santa Cruz mountains. In ArcGIS Pro 2.9, when I used Extract LAS to extract a smaller extent the resulting .lasd is missing its &...
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las2las - Reproject (shift) from shifted X,Y projection to original projection

I have a .las projected in a shifted EPSG:2100 projection. Coordinates are shifted by X,Y as following: X: 58xxxx -> xxxx Y: 414yyyy -> yyyy For EPSG:2100, projection parameters are given here:...
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Do i lost precision when importing LAS files with PDAL?

I check pdal info and see that bbox has 15 digit numbers: "boundary": { "type": "Polygon", "coordinates": [ [ [ 1528634.540273188613355, 403421.710437842586543, ...
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LiDAR: Classify overlap using Whitebox removes points in non-overlapping areas

I'm trying to classify/remove flight line overlaps in .las-files using the Whitebox toolset. The LAS file has a band in the centre where two flight lines overlap. When I run wbt.classify_overlap, the ...
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How do you create a point layer of tree locations from LiDAR?

I am using ArcPro 2.3, and need to create a point layer that is the location of trees. I have LiDAR that is classified as ground and not ground, and so from that I was able to create a DEM, DSM, and ...
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Segmenting trees from a LiDAR file (LAS) in R language [closed]

Are there ways of using data from the LiDAR file (LAS format), to do tree segmentation? I tried to study this question. I tried use example of processing .las file in R on this resource http://www....
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Losing all information when merging two LiDAR tiles

I am trying to create a raster mosaic by merging multiple LiDAR MHC (canope heignt) tiffs. They have the same CRS but have different elevation ranges. For instance, one can be 0-35.46m and the other 0-...
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Importing LiDAR data and additional info to database with pdal pipeline

I have a pipeline.json file that inserts laz files into the database. This creates a default column "pa" in the database and successfully inserted the associated value in each row. I need to ...
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Convert .LAZ to .LAS without LAStools or command line (QGIS 3.22.4)?

Is it possible to convert .LAZ to .LAS in QGIS (without LAStools)? Tools such as r.in.lidar (GRASS) used for conversion of point cloud to raster require .LAS as input, but after much searching around, ...
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-1 votes
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Creating Raster from LAS tiles [closed]

In ArcGIS, I'd convert LAZ --> LAS... then "Create LAS Dataset" and finally "LAS Dataset to Raster" Can someone help a brother out and drop the process to get me from point to ...
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1 vote
3 answers
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Terracing / stepping artefacts after converting lidar DTM from float32 to uint16

I am a beginner QGIS user, using it to supplement other skill sets in 3D modelling and rendering. I am trying to use UK lidar data in Blender to render 3D topographic maps. For this to work correctly ...
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Using LiDAR-Derived DEM to Identify Aerial Sewer Lines

I am trying to come up with the best process for identifying aerial sewer lines (typically over streams) using the pipe inverts and a LiDAR-derived DEM. In other words, locate the lines where the Z ...
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Why is QGIS contour generating tool not working with my DEM tiff file?

First a note about previous data processing. My original data (from a LIDAR scan) is a text .asc file with the internal structure looking like this: 457758.77;110272.34;353.89 457758.77;110273.34;353....
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Install LiDAR packages in Debian Bullseye

I'm trying to work with las2las in my Debian Bullseye. I'm not able to install LIBLAS packages because it seems not available in Bullseye repo. So I start to compile by myself from here https://liblas....
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Determining pixel size based on LiDAR point cloud density

I have a point cloud with a density of 8 points/m². I would like to generate a digital elevation model (DEM) from it, but I don't know what resolution to set as the raster pixel. So I would like to ...
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GEDI on GEE: Mismatched type for band 'beam'

I am trying to find, clip and download some GEDI data from GEE and I'm getting a casting error. My simple code is: var GEDI = ee.ImageCollection('LARSE/GEDI/GEDI02_A_002_MONTHLY') .filter(ee....
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PDAL reprojection rendering unexpected results

I am using a program where a Digital Elevation Model is produced from LiDAR data. The code is written in python 3.8 using the PDAL 2.3.0 library. I have a requirement to update the reprojection from ...
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Using pdal filters.divider to split LAS into multiple xyz-files

I'm runnig a pdal pipeline to do some pointcloud processing and finally I want to write to multiple xyz-files using the filters.divider. It works as expected if writing to Las-files using type: writer....
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Projecting LAS to local coordinates using lastools

Is it possible to project LAS files using Open source tools eg. lastools if using a less common coordinatesystem like local swedish espg: 3008 as destination and espg: 3006 as source? I see 3008 is ...
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Merging LiDAR files using R [closed]

I am downloading LiDAR files (.laz) from https://apps.nationalmap.gov/downloader/#/. How can I merge multiple files together using R? Note that this related to Merging multiple LiDAR (.las) files ...
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Converting LAZ to LAS using laspy

I would like to convert .laz file to .las. I am using Python and I have installed laspy with lazrs extension. I tried in Pyscripter (v4.0) following solution (this solution was mentioned here: Reading ...
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Highest LiDAR point return per sq m?

I currently have at my disposal QGIS and Trimble Business Center. I am looking for semi-automated solution for extracting the single highest lidar point return per square meter. My area of interest is ...
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How to get las Zref values after normalization in lidR?

I understand that normalize_height() in lidR creates a Zref attribute so that it can be unnormalized. While I can print Z for the normalized file, I cannot print Zref. Subsequently, when I apply ...
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What tools/methods are there for spatial autocorrelation with raster data in ArcMap?

I'm using high resolution LiDAR data to find patterns in canebrakes. My hypothesis is that cover (represented by point density per cell) will be more homogeneous between height strata in canebrakes ...
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LAS catalog not loading - Error in sp::SpatialPolygons

I am getting this error that I have never received before. I have tried loading data in the catalog format with multiple LiDAR files including the Megaplot.laz data built into the lidR package. ...
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1 vote
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How to filter all but last returns using lidR?

I am using the great lidR package and want to check all points classified as ground which are not the last returns. How would I do that? Something like this would this would be logic for me but its ...
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2 votes
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Change vertical unit in a LAS/Z file with PDAL

I am using pdal translate to filter and transform some lidar files. One issue we have are the vertical units. Sometimes they are correctly specified, sometimes they are not, and sometimes they are ...
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Can I create .las or .laz files from .hgt, .tiff, .gpx/kml or .asc files?

I have got into a golf simulator game and want to recreate my home course. Problem here is that the only import way for height information is a LAZ or LAS file. So I am looking for a way to work ...
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1 vote
1 answer
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Custom contours on DEM [closed]

I've made a DEM using LIDAR, and I'd like to mark specified contours on it as polylines. Is there a way I can create custom contours for specific heights OD? I can use either QGIS or ArcGIS Pro to do ...
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Problem using lidR functions on Mac

I have been going through LiDAR processing tutorials for R and was successfully able to get through this one by NEON about 4-5 months ago: https://www.neonscience.org/resources/learning-hub/tutorials/...
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Fix point cloud lidR - normalize_height fails

I'm working on an airborne lidar survey of around a thousand tiles (500m * 500m) using LAScatalog with lidR. I firstly ran a las_check()... No issues reported: las_check(CTG_Bertrix) #> Checking ...
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Efficiently write LiDAR data to CSV with data.table::fwrite

I have a LiDAR file (.las) that I ran through my R function: writelas2csv <- function(x,y) { lasinspatpt <- list(as.spatial(readLAS(x))) write.csv(lasinspatpt, y, row.names = T) } but as we ...
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lidR: las_check deep = T failed while deep = F succeeds

I want to run some test on a LAScatalog object using las_check with lidR in R. The first run worked just fine (all flags were green) and when I tried to run the same las_check(ctg_bertrix, deep = T), ...
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