ISPRS WG 1 / 2ISPRS WG 1 / 2

Banff 2005 WorkshopBanff 2005 Workshop

The Status of Lidar Today and Future Directions

Mike RenslowSpencer B. Gross, Inc.

June 8, 2005

Presentation Outline

• Focus on Commercial Systems and Services– Airborne Terrestrial Mapping & Bathymetric Systems

(Small Footprint)– Statistics Include Some University Systems and

Specialized Systems• Hardware and Software• Applications and Examples• Technical Challenges• Future Directions

Lidar Systems

• Approximately 140 Systems Worldwide• Commercial Manufactures

– Optech, Leica Geosystems, & TopEye make up 70% of Operational Systems

• Custom-built Systems– TerraPoint, Spectrum Mapping, and others

• Variable Levels of Performance– 4 kHz to 100 kHz with Variable Capability

Lidar Systems In-Place(Either Delivered or Developed)

0

5

10

15

20

25

1999 2000 2001 2002 2003 2004 2005?

Systems Sold

Total Lidar Systems

020406080

100120140160

1999 2000 2001 2002 2003 2004 2005?

Systems SoldTotal Systems

Lidar Systems

• Raw Data Collection, System Calibration, and Processing Software Vary– Established Vendors have Documented Their

Processes– All Arrive at Measurable Results with

Reporting Methods• Ranging Capability and Returns Recorded

Vary– Older Systems Still in Use

Lidar Project WorkflowLidar Workflow Example

System Performance

020406080

100120140160

1999 2000 2001 2002 2003 2004 2005

kHz

Lidar Systems

• Ranging and Number of Returns– First Only, First & Last, Last Only, Discrete Multiple,

and Multiple with Last of Many• Intensity Data

– Analyze Directly or Convert to a Raster Image• Point Density

– Sub-meter to 10 meters Dependent on Application– 100 kHz Appears to be the Technological Threshold for

“Traditional” Lidar Mapping (Toth, 2004)

– Low Flight Altitudes & Slower Air Speed Are Used to Achieve High Density Spacing

Lidar Systems

• Operational Flight Altitudes– 100 m to 6,000 m

• Multiple Return Advantage– 1st Returns for the “Reflective Surface”– Intermediate Returns for Canopy Analysis and

Characterization– Last Returns for Bare Earth Terrain Models

Hardware & Operational Directions

• Higher Density Data Sets– More Points on the Ground– Increased Representation of Canopy Elements– Better Defined Terrain Breaks

• That is, Smaller Surface Changes can be Identified

– Easier and Accurate Delineation of Man-made Features

• Breakline Features, Buildings, Roads

Hardware & Operational Directions

• Collection of Intensity Data– Useful for System Validation & Strip

Adjustment Using Least-squares Matching – Ancillary Data Source for Data Processing

• Separate General Land-use Categories (Example)

– Obtained During Low-light Conditions– Useful in Evaluating Surface Characteristics– Value of Being Ortho-metric

Lidar Intensity Image Sample

15 Flight Strips, Mosaiced & Tone-matched, 171 MB GeoTIFF, Orthometric Image

Hardware Directions

• Smaller and Lighter and Portable• Smaller Supporting Components

– IMU and Storage Devises• Increased Computing Capability• Compatible with Existing “Camera Mount”

Configurations• Reduced Platform Power Requirements

ALS40 and the ALS50 Lidar Scanners

Leica GeoSystems

DATIS II Lidar Scanning System

Spectrum Mapping, Inc.

ALTM 3100 Lidar Scanning System

Hardware Directions

• Additional Laser Wavelengths– Robust Bathymetric Systems– Several R&D Systems

• Multi-wavelength Laser Pulses– “Hyperspectral Lidar” (Example)

• Shorter Distance Between Return Values• Full Waveform Capture• Increased Accuracy

Hardware Directions

• Integration with Other Sensors– Metric Digital Sensors– Multispectral Sensors– Hyperspectral Sensors– Satellite Imagery– Supported by Geo-positioning Technology Recorded by

the Lidar System– Supported by Direct Calibration of CCD-based sensors

• Model the Anomalies of the CCD

Software Directions

• Trend Towards A Totally Integrated Workflow from Collection to Delivery– Lidar System Vendors Are In Development– Photogrammetric Vendors & Firms Are in

Development– Service Firms Are Developing Workflows for Specific

Applications• Iterative Surface Modeling Software

– Processing the Point Cloud– Analyzing the Relationship Between Returns in 3D– Intelligent Data Thinning

Software Directions

• Increased Use of 3D or Holographic Visualization for Editing and Analysis– New Generation of Very Fast, Versatile, and

Robust Software• Lidar-grammetry

– Combine Softcopy Photogrammetry for Breakline Production and Final Editing

– Stereo Intensity Imagery

Software Directions

• Target-based Calibration Methodologies• Development of Analysis Tools

– Specific to the Discipline• Direct Interface with GIS Software

– ESRI’s Next Version of ArcGIS• Further Data Format Standardization

– .LAS is the Accepted Transfer Standard – Expanded Deliverable Standards for Surface

Models and Point Clouds

Software Directions

• Automated Feature Extraction• Automated Change Detection• Incorporation of 3D Position with

Radiometry Data– “X,Y,Z – R,G,B” Data Sets (and/or with CIR)– “Bio-Spatial” Data (Steve Reutebuch, 2005)

• Attaching Biologic Information to the ‘Lidar GeoDataBase’

Lidar Trends

• Lidar is Widely Accepted As a Viable Mapping Tool

• Acceptance as a Multi-purpose Remote Sensing Technology

• Technology and Processes Have Stabilized• Increased Capability, Expertise, Experience,

Research, and Competition• Stabilized Cost for Services

Today’s ApplicationsFloodplain Mapping Local Government Highway DesignAirport Obstructions Utility Corridors Elevation DataSpecies Habitat Forestry TelecommunicationsEarthwork Estimates Volume Change Disaster ResponseFeature Extraction Landslide Analysis Plate TectonicsFire Fuel Assessment Fault Measurements Restoration ProjectsMudflat Mapping Snow & Ice Mapping Change DetectionLand Use Mapping Bathymetric Mapping Underwater FeaturesGeologic Mapping Transportation Analysis ArcheologyVehicle Velocity Resource Visualization Pipeline MappingMineral Resources Hydrographic Features Urban MappingWater Quality Harbor Passage Analysis Radar FusionStereo Analysis Urban Vegetation Watershed AnalysisEnvironmental Hazards Water Turbidity Land Cover Mapping

**Presentations at This Meeting**

Hyperspectral Lidar(Samberg et al., 2005)

SPECIFICATIONS:

50 to 500 meters Flight Height (Typically in a Helicopter)

Excimer Laser

150,000 Pulses per Second

300 to 550 nm Wavelength

Integrated GPS/INS

Video Camera

Weight: 375 kg. (827 lb.)

TECHNOLOGY:

Based on the Spectral Fluoresce Signature of the Target (Oil Pollution in this example)

http://www.ldi3.com/index.php?main=42&articleID=30

Hyperspectral Lidar

Hyperspectral Lidar

Hyperspectral Lidar

Classification by Lidar Return • Discrete Multiple-Return LIDAR Data Contains

Information Beyond Simple X-Y-Z Values– Number of Returns from a Pulse– Vertical Distribution of Elevations – Type of Reflection: “First & Only”, “Last of Many”, etc.

• These Can be Used to Delineate Different Types of Land-cover: for Example,– “Last of Many” Points are Only Found in Vegetated Areas– Difference Between Highest/Lowest Points in an Small

Area can Differentiate Trees from Shrubs– Vertical Distribution can Indicate the Type or Maturity of a

Forest Area

Example from EarthData

Reference Orthophoto(QC and parameter selection)

BareEarth LIDAR DEM

LIDAR CanopyData

Base Classification•Open/Grass•Scrub/Shrub•Wooded•Water/No Data

Unfortunately, urban developments are often misclassified as wooded areas

Reference Orthophoto(QC and parameter selection)

Density GRID of Final Returns

“Last-Of-Many”LIDAR Points

Secondary Classification•Vegetated•Cleared

Secondary Classification

Base Classification

Final Classification

The results from these two classification processes are merged …

Reference Orthophoto(QC and parameter selection)

Final Classification•Open/Grass•Scrub/Shrub•Wooded•Water/No Data•Built-Up

Transparent overlay of Final Classification on reference orthophoto.Confusion in the urban areas has largely been resolved.

Technical Challenges

• Georeferencing– Very Dependent on GPS

• System Performance / Calibration– Require Objective Measures for System

Performance and Standardized Reporting– Agreement on Best Practices– Define the Effect of Flight Altitude on

Accuracy

Institutional Challenges

• Standardized Contracting and Performance Measurement Standards

• Standardized Metadata Reporting• Explicit Definition of the Error Budget

– Sensor Positioning Errors (GPS/IMS)– Sensor Calibration Errors– IMU Errors– Atmospheric Changes and Effects– Noise Errors

Conclusions

• Continued Algorithmic Developments for Surface Models & Feature Extraction

• Sensor Fusion• Merging Range Data with Optical and

Radiometric Data• Model-based Feature Extraction• Merging Airborne Lidar with Ground-based

Lidar

Conclusions

• Relative Stability in Sensor Development by the Major Providers

• New Methodologies for Increasing Point Density– Multiple Wavelengths (2 or 3) and Multiple Return

Detectors

• Increased Product Demand from the Users• New High-performance Visualization Tools• More Research & Development & Custom-built

Systems

Mike Renslow

Spencer B. Gross, Inc.

13545 NW Science Park Drive

Portland, OR 97229

(P) 503-646-1733

(E) <mike@sbgmaps.com>www.sbgmaps.com