LiDAR Tools, Applications and

Experiences

Overview

• October 2006 GRF LiDAR Data Collect

• Data Issues ….

• LiDAR tools, products and application areas

• Recent GRF LiDAR Projects

• Lessons Learned…

LiDAR Defined

• LiDAR is a an acronym for Light Detection And Ranging that relies on measuring the distance from an aircraft to the Earth’s surface by precisely timing the round-trip travel time of a brief pulse of laser light

• The travel-time is measured from the time the laser pulse is fired to the time laser light is reflected back from the surface.

• The reflected laser light is received and converted to distance from the plane to the surface based on the speed of light.

LiDAR Data Collection

Laser Pulse Returns

2006 AGRG

LiDAR Data Collect

3-Stage LiDAR Data Collection and

Management Process 1. Identification of Study Area

2. Supply study area background files

3. Flight Planning

4. GPS Base Station Operation (Ground Crew)

5. Hardware Install (Flight Crew)

6. In-Flight Data Collection

7. Raw data processing

8. Point Classification and Export

9. Creation of DEM’s and other products

Pre-Flight

Post-Flight

Collection Day

Identification of Study Area

Supply of Background Files

Provided the following;

• Georeferenced NTS Topo Map Image

• Rivers, Roads etc. as shapefile vectors

• Survey Monuments text file

Selected Best Available Base Station Monument

Flight Planning Optech’s ALTM Nav Software is Used to Plan Flights

Hardware Install

2005 AGRG Summer LiDAR Workshop

?

540 km by Air!

Flight Leaves Late from PEI…Yes I said PEI

GPS-Base Station Set-up

96G7002 CRK 120 48 56 38.4634 57 56 59.0467 100 Y A R 2003 68.554 100 1 P 1 CGVD28 1999 1 1 012A13

98F001 98F001 100 48 56 38 57 56 59 S S 64.970 100 1 P 1 CGVD28 1999 1 1 012A13

98F002 98F002 100 48 56 38 57 56 59 S S 66.563 100 1 P 1 CGVD28 1999 1 1 012A13

96F003 96F003 100 48 56 38 57 56 59 S S 67.709 100 1 P 1 CGVD28 1999 1 1 012A13

In-Flight Data Collection

• Pilot maintains course(and checks fuel level!)

• Technician maintains Laser and data checking

Raw Data Processing

Data Sources

• Aircraft Global Positioning System (A-GPS)

• Base Station GPS

• Inertial Measurement Unit (IMU)

• Inertial Navigation System (INS)

• LiDAR Returns

Applanix PosPac Software

Raw Data Processing (ALTM Workflow)

SBET File

A-GPS Base Station GPS IMU INS + + +

•Raw Flight Data is processed in PosPac to create an SBET File.

•PosPac is used primarily for 3d sensor location.

Raw Data Processing

Optech REALM Software

LiDAR Return

Data

LAS Binary File

SBET File +

SBET file and LiDAR return data is processed to create a LAS Binary File

Point Classification and Export LAS files are processed in TerraScan to classify points as vegetation, ground, non-

ground etc.

LAS Binary File

Vegetation Ground Non-Ground

TerraScan (Microstation)

LAS Files

• LAS (LASer) contains LiDAR point data

records which combine GPS,IMU and

laser pulse returns to produce X,Y and Z

point data.(others too like intensity…)

• ASPRS Open Data specification/standard

and format

• Specification now at version 1.4, 2.0 is in

the works

Item Fmt 0 Fmt 1 Fmt 2 Fmt 3 Fmt 4 Fmt 5 Fmt 6 Fmt 7 Fmt 8 Fmt 9 Fmt 10

X X X X X X X X X X X X

Y X X X X X X X X X X X

Z X X X X X X X X X X X

Intensity X X X X X X X X X X X

Return Number X X X X X X X X X X X

Number of Returns (given pulse) X X X X X X X X X X X

Scan Direction Flag X X X X X X X X X X X

Edge of Flight Line X X X X X X X X X X X

Classification X X X X X X X X X X X

Scan Angle Rank X X X X X X X X X X X

User Data X X X X X X X X X X X

Point Source ID X X X X X X X X X X X

GPS Time X X X X X X X X X

Red X X X X X X

Green X X X X X X

Blue X X X X X X

Wave Packet Descriptor Index X X X X

Byte offset to waveform data X X X X

Waveform packet size in bytes X X X X

Return Point Waveform Location X X X X

X(t) X X X X

Y(t) X X X X

Z(t) X X X X

NIR X

TerraScan Classification Options

Point Cross-Section

Point Classification and Export

Classified LAS points are exported as ascii xyz files

Vegetation Ground Non-Ground

Ground.xyz Non-Ground.xyz Vegetation.xyz

TerraScan

RESULTS

OCTOBER 2006 LiDAR

Lots of Points…..

343,083,691 Total Points!

More than 25GB of Data!

Tiles make data Manageable

523 tiles in all

Delivered Data Formats

• 14 industry standard LAS binary all hits files.

• 523 ASCII space delimited x,y,z,i files for

Ground Only Returns

• 523 ASCII space delimited x,y,z,i files for All

Hits

Derivative Product Development

Reformatted ASCII

Raster

ASC Raster

GDB

Raster

Mosaics Surfer

Grids

Shapefiles

DEMS

DSM Slope

Grids

Vegetation

Grids

Aspect

Grids

Hillshade

Grids

342475

Ground Points

Points

DEM from Ground Points

Hillshade

Slope

Aspect

Surfer Tile294 All Hits

Surfer Tile294 Ground ONLY

Selected LiDAR Software • TerraScan (Part of TerraSolid)

• Surfer

• QT Modeler

• LP360

• LiDAR Analyst

• LASTools

• Voxler

• Pointools

• ArcMAP/ArcToolbox

Terrasolid(Terrascan)

Surfer

QT Modeler/Reader(Applied Imagery)

LP360 in ArcMAP

LiDAR Analyst (Overwatch)

LasTools(Martin Isenburg)

• * txt2las.exe converts LIDAR data from ASCII text to binary LAS format

• * las2txt.exe turns LAS into human-readable and easy-to-parse ASCII text

• * lasinfo.exe prints out a quick overview of the contents of a LAS file

• * las2shp.exe turns binary LAS into ESRI's Shapefile format

• * shp2las.exe turns an ESRI's Shapefile into binary LAS

• * lasmerge.exe can merge several LAS files into one

• * las2las.exe extracts only last returns, clips, subsamples, etc ...

• * lasthin.exe implements a simple point thinning algorithm

• * las2tin.exe triangulates the points of a LAS file into a TIN

• * las2dem.exe rasterizes them into a DEM

• * las2iso.exe extracts, optionally simplified, elevation contours

• * lasview.exe visualizes the contents of a LAS file.

• * lasclip.exe clipping LiDAR points

• * ArcGIS for Desktop toolbox.

Voxler (Golden Software)

Pointools (Bentley)

ESRI Las Dataset

ESRI Tools

• Point File Information

– file name, point count, z-minimum, z-maximum,

and point spacing

• LAS to multipoint

• LAS Point Statistics as Raster

– pulse count, return count, intensity range …others

• LAS Dataset to Raster

• Entire Section dedicated to LAS in help

including Canopy Height workflow

2006 Data Issues

and

Processing …Screw-ups !

OCTOBER 2006 LiDAR

Holes!

City and Marble Holes

Low Point Density

• 0.63 points/Square m

• Up to 15 points m2 possible

March 2009 before all issues were fixed…….

Applications

(For good LiDAR!)

What is it used for ?

• Lidar data can be used to accurately measure the topography

of the ground, even where overlying vegetation is quite dense.

• The data can also be used to determine the height and density

of the overlying vegetation, and to characterize the location,

shape, and height of buildings and other structures.

Selected Products, Uses and Applications

• High Accuracy DEM (Derived Products Slope, Aspect etc..)

• 3D fly through simulations

• Landscape visualizations

• Tourism and Municipal applications

• Accurate contours for a variety of mapping applications

• Geophysical applications and visualizations

• Flood Hazard Mapping, Coastal zone mapping and assessment

• Delineate vegetation height and type

Classified LiDAR(Leading Edge Geomatics)

RGB Classified LiDAR (Leading Edge Geomatics )

Recent GRF LiDAR Projects

• LiDAR /Ortho Data Collection for 10 sites in

Western Newfoundland collected in July 2010

– Avalanche Research with MUN SWG Campus

– Geohazard Monitoring in conjunction with CCRS

• New flight planned for this Summer 2013

Avalanche Hazard Maps

Avalanche Services/Web Apps

Google/JavaScript App

LiDAR GeoHazard Sites

The houses are constructed on a marine

terrace with a surface elevation of about 24

m above present sea level. The Northern

Peninsula Highway is located about 20-70

m inland of the cliff edge, between which

14 buildings were located. October 20, 2006

April 15, 2007

Newfoundland, Canada

Daniel’s Harbour:

RADARSAT-2 Ultra Fine

Master: 20090610

Slave: 20090914

Descending Orbit

Perpendicular Baseline: 67 m

Deformations are only shown where the scene coherence exceeds 0.5

RADARSAT-2 - 3x3 multi look intensity image

-50 0 50

Vertical displacement [mm]

April 2007

There is no an existing high resolution DEM. Therefore, 3-pass

differential interferometric processing applied to monitor the

temporal evolution of landslide.

Daniel’s Harbour – InSAR Displacement Map:

ArcMAP WorkFlow

LAS Files Multipoint

FeatureClass Terrain

1m Raster

DEM

HillShade

Slope

Aspect

Focus Area (Daniels hr.)

MultiPoint Featureclass

Terrain

1m Raster

Hillshade

Slope

Aspect

Some Lessons Learned

• Data areas need a specific purpose/focus. The

data collect can be tuned to needs( forest

metrics, DEM etc. No one flight can do it all!

• Do your homework know what to ask for.

Some vendors will only provide x,y,z if that is

all you ask for. Lots of other useful info

“hides” in your LiDAR…

• Manage stakeholder expectations (software,

formats, coordinate system(s))

Lessons Learned

• Discuss data sharing policies and distribution

between partners, vendors and external

stakeholders

• Don’t be locked into a single GIS platform use

the best tool for the job(Some SW slow….)

• Leave the raw LiDAR processing to the

vendors focus on “GIS ready deliverables”

• Use a reputable experienced vendor (Highly

recommend Leading Edge Geomatics.

Lidar Project Partnerships