LiDAR 101

• Find the Vendor Report!
• LAS/LAZ
• All Returns
• Ground
• Rasters
• Bare Earth
• High Hit
• Intensity
• Vectors
• Boundary Area
• Tiles
• Flightlines
• SBET (smoothed best estimate trajectories)

Credit: XKCD

History

Requirements

www.xsens.com

• GNSS
• IMU
• Scanner
• NOAA CORS
• Private Basestation

http://geodesy.noaa.gov/CORS/

• First optical LASER was developed late-1950s
• 1st laser ranging tried at that time!
• Development through 1970s, including hydrographic and bathymetry application.
• Accurate GPS in the 1980s.
• Mid 1990s Prof. Fredreich Ackerman suggests laser profiles to create accurate DEM in forests.
• Late 1990s, GPS and IMU combined to make first ALS scanners (Linear-mode)
• 2004 Waveform digitiziation
• 2000s Military-use of Geiger-mode and Single Photon counting
• 2006 double scanners
• 2015 Geiger-mode announced for public
• 2017 Self-driving cars in most metro cities

Ackermann, F. 1999. Airborne laser scanning—present status and future expectations. In ISPRS, 1999 pp. 64-67.

Baltsavias, E.P. 1999. Airborne laser scanning: existing systems and firms and other resources. In ISPRS, 1999 pp.

164-198.

NASA ICESat

SLAM

https://www1.ethz.ch/igp/photogrammetry/education/lehrveranstaltungen/Photo2_FS15/course/ALS-Baltsavias_2014a.pdf

http://forsys.cfr.washington.edu/JFSP06/publications/Carson_et_al_2004.PDF

https://www.aip.org/history/exhibits/laser/sections/raydevices.html

Terrestrial

Terminology

http://earthobservatory.nasa.gov/IOTD/view.php?id=77637

http://blog.lidarnews.com/stencil-follow-up/

http://science.nasa.gov/missions/gedi/

Vehicle-mounted

Manned-aerial

• LAS – format supports the exchange by 3-dimensional x,y,z tuplet.
• RMSE – abbreviation for 'root mean square error'; measure of the accuracy of the data similar to the measure of standard deviation if there is no bias in the data.
• Accuracy & Fundamental Vertical Accuracy (FVA) – a measure of the accuracy of the data in open areas at a high level of confidence (95%).
• Classification – data that have been processed to define the type of object, e.g. bare earth, buildings, vegetation, or unclassified.
• Returns – first, second, third, and ultimately the “last” return from a single laser pulse, can help determine what the reflected pulse is (e.g., ground, vegetation).
• Point Spacing – also called “posting density” or “nominal point spacing.”
• Pulse Rate – per second the lidar instrument is firing. Systems now exceed 1 Mhz (million pulses / sec).
• Intensity – object reflected wavelength of light used by the laser system
• RTK GPS (Real Time Kinematic GPS) – satellite navigation that transmits Global Positioning System (GPS) signal at much higher frequency than standard units - resulting in more precise survey.
• DEM or 'Digital Elevation Model' – a surface created from ground points data to represent the topography.
• DSM or 'Digital Surface Model - a surface created from the high hit point data to represent the actual surface including vegetation.
• CHM or 'Canopy Height Model' - CHM = DSM - DEM, represents the object heights above ground height

Unmanned-aerial

http://www.nap.edu/openbook/

http://iopscience.iop.org/article/10.1088/0034-4885/76/8/086801

credit: Beland et al. 2015

http://www.lidarmag.com/PDF/LiDARNewsMagazine_Sitar-25percentIncreaseInCollectionEfficiency_Vol5No4.pdf

http://www.mdpi.com/2072-4292/6/10/9951/htm

Image: Robert McGaughey, USFS PNWRS

Acronyms will be flying around the room!!

Applications

American Society for Photogrammetry and Remote Sensing

American Standard Code for Information Interchange

Inertial Motion Unit

Look out!

International Society for Photogrammetry and Remote Sensing

Global Navigation Satellite System

• Phenotyping, species ID
• Hazard / change detection
• Multi-spectral imagery fusion

Global Position System

Light Amplification by the Stimulated Emission of Radiation

Light Detection and Range

• ASPRS
• ASCII
• IMU
• ISPRS
• GNSS
• GPS
• LASER
• LIDAR
• LAS
• LAZ
• SLAM
• USGS
• FUSION
• PDAL
• ALS
• TLS

Log ASCII Standard or LASer format

Multi-spectral and Hyperspectral imagery

LAS-Zipped

LiDAR 101

example from a savannah ecosystem in S. Africa (Colgan et al. 2012) - flown with the NEON prototype hyperspectral camera.

Simultaneous Localization and Mapping

Macroynms!

United States Geological Survey

Forest Service's free LiDAR software

Point Data Abstraction Library

Image source: NEON

Aerial Laser Scanning

Terrestrial Laser Scanning

Remote Sensing 2012, 4(11), 3462-3480; doi:10.3390/rs4113462

by Tyson Lee Swetnam

You will (hopefully) learn:

Best Practices

Origin: 5/21/2012 Latest update: 11/14/2018

Ensure quality data are collected!

• Read the literature (see links at end of this talk)

tswetnam@cyverse.org

• What lidar is
• Why lidar has cool applications
• How to collect & order lidar data & distinguish between lidar data products
• Where the technology is headed

tyson-swetnam

tswetnam

ALS

• New systems are much faster than older technology
• vendors still sell the same point density while reducing their costs
• Understand ALS has large uncertainty relative to TLS (e.g. 10cm RMSEz vs 5-8 mm RMSE) due to GNSS
• Ensure flight lines are collected with 100% overlap.
• Overlap and Withheld points are classified in the cloud.
• Density is high enough for your application
• e.g. USGS QL1 = 8-12 ppsm, QL2 = 2 ppsm, QL3 = <1 ppsm

Part II: "Dr. Strangedata or: How I learned to stop worrying and love point clouds"

http://pubs.usgs.gov/tm/11b4/

Where is the technology headed

Lecture 2 - What you'll learn

Hosting and providing data

• Linear-Mode is a mature technology
• Well established in the vendor community
• New features like smart swath tracking and multi-spectral lasers
• Geiger-Mode and Single photon are new market tech
• Potential to collect 10x larger area at a time
• Flash LiDAR (Time of Flight Camera)
• Real-time
• Small form factor

http://openlayers.org/

http://www.teledyneoptech.com/index.php/product/titan/

What do you get?

http://postgis.net/

Points, billions of points!

• What is the near future of LiDAR?
• Technological leaps (Geiger, Single Photon, Flash)
• 3DEP
• LiDAR Base Specifications
• Where to find LiDAR data
• What to do with the data after you've got it
• Useful tools for viewing, editing, working with data
• How to make derivative products which you can look at, analyze, serve to your customers/users

http://www.sketchup.com/

• What is 3DEP?
• Linear-mode vs Single-Photon and Geiger-mode
• http://www.teledyneoptech.com/index.php/product/titan/
• http://www.sigmaspace.com/single-photon-lidar
• http://govcomm.harris.com/solutions/intelliearthgeospatialsolutions/geospatialcollectionsolutions.aspx
• TLS vs UAV vs ALS: what should you use?
• http://www.riegl.com/nc/products/terrestrial-scanning/
• http://www.phoenix-aerial.com/
• https://quantumspatial.com/
• Why you should use (or at least know) open-source software
• https://trac.osgeo.org/osgeo4w/
• http://www.saga-gis.org/
• http://www.qgis.org/en/site/
• http://opentopo.sdsc.edu/tools/listTools
• Prep for lab:
• pre-installation of software: https://pods.iplantcollaborative.org/wiki/display/~tyson_swetnam/LiDAR+Lab
• Read suggested material
• https://darchive.mblwhoilibrary.org/handle/1912/7437
• https://coast.noaa.gov/digitalcoast/_/pdf/lidar101.pdf
• http://pubs.cif-ifc.org/doi/abs/10.5558/tfc2013-132

• OpenLayers
• PostGIS
• SketchUp
• PoTree
• Harvest4d
• Entwine

http://www.spar3d.com/news/lidar/apples-lidar-3d-video/

http://potree.org/

https://harvest4d.org/

http://potree.entwine.io/

http://www.harrisgeospatial.com/

http://potree.entwine.io/

USGS Apples to Apples (Linear v Geiger v Single Photon)

• Point density and relative accuracy of the two new sensors are adequate
• non-vegetated surface accuracy is within USGS base spec
• Performance is poor in leaf-on, best in leaf-off
• USGS base spec needs to be updated for the new tech

http://www.sigmaspace.com/single-photon-lidar

• Intensity
• Elevation
• Bare Ground

Viewing the data

3DEP - The 3D Elevation Program

http://nationalmap.gov/3DEP/

TLS

• Ensure 100% illumination of target area.
• consider a central 360 degree scan, and 3 outer scans at 120 degree angles looking inward
• Get up - find ways to elevate above your target
• Find a high point (building, hilltop)
• Taller tripod
• Rent a scissor lift
• Don't buy a drone! Too risky...
• Position enough targets in the area to move your sensor multiple times.
• Sensor needs at least 3 targets to reference multiple scans

• Potree
• Entwine

https://geosciences.univ-rennes1.fr

• USGS program to collect enhanced elevation data in the form of high-quality LiDAR over the coterminous USA.
• 8-10 Year acquisition period.
• States are now being awarded grants for huge collections

Where is technology headed?

What do you do with them?

• CloudCompare
• LASTools
• FUSION
• QGIS
• SAGA
• R
• ArcGIS*

10+ years

Available

https://pods.iplantcollaborative.org/wiki/display/~tyson_swetnam/ILMF2016

Multi-channel LiDAR

Hyper-spectral LiDAR (Supercontinuum Lasers)

• Cloud Metrics
• Segmentation
• Object Recognition

• Classify!
• Meshes
• Rasters

USGS LiDAR Base Specification v 1.2

http://pubs.usgs.gov/tm/11b4/

Viewing Metadata

• Published in 2012, updated 2014
• Established standards for LAS which meet the 3DEP
• 4 Quality Levels (QL)

Image source: The Verge

http://www.dirsig.org/docs/new/images/lidar

• LASTools*
• FUSION
• SAGA
• PDAL
• QGIS
• R
• ArcGIS*

Image source: NCALM

Image source: Fianium Ltd

Ranging Devices

Species discrimination via active hyperspectral laser

http://www.fosternav.net/project.htm

Image source:

Google Project Tango

http://www.exelisvis.com/Home/NewsUpdates/TabId/170/ArtMID/735/ArticleID/14781/Geiger-mode-LiDAR-vs-Typical-LiDAR-.aspx

LAS 1.4

What to expect in a delivery dataset

Species discrimination via passive hyperspectral cameras

Sensors 2011, 11(1), 32-53; doi:10.3390/s110100032

Layout

• Public Header Block
• point counts, data boundary
• Point Data Record Format (PDRF)
• Well Known Text (WKT) encoding of Coordinate Reference System (CRS)
• No longer GeoTIFF
• Variable Length Record (VLR)
• projection info
• metadata
• waveform packet info
• user app data
• limited in size to 64 kb
• Extended Variable Length Record (EVLR)
• appended at the end of file to allow editing
• can be any size

http://www.advancedscientificconcepts.com/

ftp://lidar.dnr.state.mn.us/documentation/LAS%20spec%201.4.pdf

Where to find LiDAR Data

What to do with the data now that you've got it?

Storage

Just a few examples

• Ideally, you should run your OS from one hard drive, store your raw data on second drive, and write your output data to a third drive.
• SSDs are your friend
• Backup your data on the Cloud
• UA provides you free, unlimited Google.Drive

• Pima County GIS - FTP Server, Data viewer
• University of Arizona Library + Spatial Data Portal Viewer
• OpenTopography - DEM and LiDAR Data
• National Elevation Dataset (NED) USGS - Maps, GIS, Apps, Data

Processing

• You decide on your favorite GIS work environment - there are plenty of tools out there to consume LiDAR

https://pods.iplantcollaborative.org/wiki/display/~tyson_swetnam/Geospatial+Data+Portals