Lidar Data Applications for Natural Resource

Management

Lidar Data Applications for Natural Resource

Management

Tom Bobbe, Mark Finco, Ken Brewer, Denise Tom Bobbe, Mark Finco, Ken Brewer, Denise LaesLaes

USDA Forest ServiceUSDA Forest ServiceRemote Sensing Applications CenterRemote Sensing Applications Center

Salt Lake City, UtahSalt Lake City, Utah

Geospatial 2007 ConferenceGeospatial 2007 ConferenceThursday - May 10, 2007Thursday - May 10, 2007

Tom Bobbe, Mark Finco, Ken Brewer, Denise Tom Bobbe, Mark Finco, Ken Brewer, Denise LaesLaes

USDA Forest ServiceUSDA Forest ServiceRemote Sensing Applications CenterRemote Sensing Applications Center

Salt Lake City, UtahSalt Lake City, Utah

Geospatial 2007 ConferenceGeospatial 2007 ConferenceThursday - May 10, 2007Thursday - May 10, 2007

Presentation OutlinePresentation Outline

Lidar system fundamentals

Resource management applications Digital Terrain Models

Vegetation Models

Lidar applications in the Forest Service

Lidar acquisition specifications

Lidar system fundamentals

Resource management applications Digital Terrain Models

Vegetation Models

Lidar applications in the Forest Service

Lidar acquisition specifications

Fundamentals of LidarFundamentals of Lidar

Lidar Basics: Lidar = Light Detection

And Ranging Scanning Infrared Laser

Rangefinder 80-150 thousand pulses

per second result in typical point densities between 8 per 1-m2 to 1 per 4-m2 (called post spacing)

Multiple returns from a single pulse are possible

Coupled with IMU/GPS provides very accurate X,Y,Z point clouds (~15-cm in Z).

Lidar Basics: Lidar = Light Detection

And Ranging Scanning Infrared Laser

Rangefinder 80-150 thousand pulses

per second result in typical point densities between 8 per 1-m2 to 1 per 4-m2 (called post spacing)

Multiple returns from a single pulse are possible

Coupled with IMU/GPS provides very accurate X,Y,Z point clouds (~15-cm in Z).

Characteristics of Lidar DataCharacteristics of Lidar Data

Point data, but … Large volume of data

Assume: 1 to 4 pulses / m2

Assume: 2 returns per pulse Assume: 6 values per return Equals: 0.38 – 1.52 GB per acre, or

3.71 – 14.84 TB per 10,000 acres Because of data volume

Often standard GIS analyses don’t work Require special pre-processing for analysis

Point data, but … Large volume of data

Assume: 1 to 4 pulses / m2

Assume: 2 returns per pulse Assume: 6 values per return Equals: 0.38 – 1.52 GB per acre, or

3.71 – 14.84 TB per 10,000 acres Because of data volume

Often standard GIS analyses don’t work Require special pre-processing for analysis

Examples of Lidar Point CloudsExamples of Lidar Point Clouds

This lidar point cloud transect crosses a forest roadThis lidar point cloud transect crosses a forest road

In this 3-D perspective of a lidar point cloud note the buildings

Points Colored by Height

Highest

Lowest

Multiple return lidar Multiple return lidar

Multiple return lidar contributes to forest structure measurements

1st return is not just top of canopy

Last (4th) return is not just the ground

First analytical step typically filters ground returns from all returns

Multiple return lidar contributes to forest structure measurements

1st return is not just top of canopy

Last (4th) return is not just the ground

First analytical step typically filters ground returns from all returns

Figures Courtesy of PNW Seattle Laboratory

All Returns

3rd Return

4th Return

2nd Return

1st Return

Primary Application – High Resolution DTMPrimary Application – High Resolution DTM

10-m DEM / 1-m Lidar DTM Comparison10-m DEM / 1-m Lidar DTM Comparison

New and important features are recognizable on the 1-meter digital terrain model (micro-hydrologic patterns, roads / trails, and other man-made features)

New and important features are recognizable on the 1-meter digital terrain model (micro-hydrologic patterns, roads / trails, and other man-made features)

USGS 10-meter Digital Elevation Model (DEM) Lidar-derived 1-m Digital Terrain Model (DTM)

Site ASite A

Site BSite B

Site ASite A

Site BSite B

Comparison AreasComparison Areas

USGS 10-meter Digital Elevation Model (DEM) Lidar-derived 1-m Digital Terrain Model (DTM)

Site A

Site B

DTM’s are just the beginning however …DTM’s are just the beginning however …

Tools are being developed in the Forest Service and commercial sector to extract information about the vegetation

Individual Tree Measurements(potentially height, crown base height, crown diameter depending on crown spacing)

Canopy Height, Cover, Density

Vegetation Structural Characteristics

Fusion SoftwareFusion Software

Developed by USDA Forest Service Pacific Northwest (PNW) Research Station (McCaughey, Reutebuch & Andersen)

Originally intended for PNW internal use RSAC agreed to distribute and provide support for FS users

Capabilities include:

View lidar data quickly and easily Handles almost any format of lidar data Creates surfaces (bare earth models (DTMs), canopy surface

models) QA/QC of vendor-processed data Easily measures heights of features Large number of forestry-related measurements And much more…

Developed by USDA Forest Service Pacific Northwest (PNW) Research Station (McCaughey, Reutebuch & Andersen)

Originally intended for PNW internal use RSAC agreed to distribute and provide support for FS users

Capabilities include:

View lidar data quickly and easily Handles almost any format of lidar data Creates surfaces (bare earth models (DTMs), canopy surface

models) QA/QC of vendor-processed data Easily measures heights of features Large number of forestry-related measurements And much more…

Fusion TutorialFusion Tutorial

Lidar TutorialLidar Tutorial

USFS PNW’s FUSION SoftwareUSFS PNW’s FUSION Software

Individual Tree MeasurementsIndividual Tree Measurements

Lidar and ground measurements relationships Lidar and ground measurements relationships

Fitted : LNMAXHT + LNMEANHT + LNCV + LNP25 + LNP50 + LNP90 + LND

LN

H40

0 1 2 3 4 5

01

23

45

Dominant height (r 2 = 0.98)

Figures Courtesy of PNW Seattle Laboratory

Strong relationships with ground measured variables

Height, Basal Area, Volume, Crown Bulk Density, etc.

Relationships verified by numerous researchers

McGaughy, Reutebuch & Andersen (USFS PNW)

Hudak and Evans (USFS RMRS) Lefsky (Colorado State) Evans (Mississippi State) Wynne (Virginia Tech) Popescu (Texas A&M) Naesset (Norway) Many others …

Strong relationships with ground measured variables

Height, Basal Area, Volume, Crown Bulk Density, etc.

Relationships verified by numerous researchers

McGaughy, Reutebuch & Andersen (USFS PNW)

Hudak and Evans (USFS RMRS) Lefsky (Colorado State) Evans (Mississippi State) Wynne (Virginia Tech) Popescu (Texas A&M) Naesset (Norway) Many others …

Lidar Applications in the USFSLidar Applications in the USFS

Recent tally of lidar applications in the USFS(Lachowski and Reutebuch)

Recent tally of lidar applications in the USFS(Lachowski and Reutebuch)

More detail and full report at http://fsweb.rsac.fs.fed.us/documents/0073-RPT2.pdf

More detail and full report at http://fsweb.rsac.fs.fed.us/documents/0073-RPT2.pdf

Lidar Mission SpecificationsLidar Mission Specifications

Wide lidar usage (in resource mapping) is just in its infancy

Like aerial photos – specifications are linked to information requirements

Currently no industry standards for specific applications

2 Areas to specify Acquisition specs Processing and Delivery

specs

Wide lidar usage (in resource mapping) is just in its infancy

Like aerial photos – specifications are linked to information requirements

Currently no industry standards for specific applications

2 Areas to specify Acquisition specs Processing and Delivery

specs

GovernmentGovernment

VendorVendor

Sp

ecs

QA

/ QC

Lidar Specifications – AcquisitionLidar Specifications – Acquisition

Acquisition Specifications Point density (post spacing)

DTM -> based on vertical accuracy requirements Vegetation Applications

1.5 point per square meter absolute minimum 4-6 points per square meter are preferable

Specify whether collected leaf on or leaf off Multiple returns per pulse Maximum 15-degree off nadir scan angle unfiltered data Flight lines should have 50% “side lap” (30% minimum) Cross flights for calibration Attributes delivered: X, Y, Z, Intensity, Scan Angle, Return

# High resolution digital imagery (if possible)

Acquisition Specifications Point density (post spacing)

DTM -> based on vertical accuracy requirements Vegetation Applications

1.5 point per square meter absolute minimum 4-6 points per square meter are preferable

Specify whether collected leaf on or leaf off Multiple returns per pulse Maximum 15-degree off nadir scan angle unfiltered data Flight lines should have 50% “side lap” (30% minimum) Cross flights for calibration Attributes delivered: X, Y, Z, Intensity, Scan Angle, Return

# High resolution digital imagery (if possible)

Lidar Specifications – Processing and DeliveryLidar Specifications – Processing and Delivery

Vendor Processing and Delivery Specifications Lidar data delivered in overlapping tiles GIS dataset of the tiling system GIS dataset of the flight lines Report on GPS ground station locations Geographic projection information (including

vertical datum) Heights should be orthometric heights Report that lists all files delivered Optional:

Tiled points filtered for bare earth returns A high resolution DTM

Vendor Processing and Delivery Specifications Lidar data delivered in overlapping tiles GIS dataset of the tiling system GIS dataset of the flight lines Report on GPS ground station locations Geographic projection information (including

vertical datum) Heights should be orthometric heights Report that lists all files delivered Optional:

Tiled points filtered for bare earth returns A high resolution DTM

Approximate Costs of AcquisitionApproximate Costs of Acquisition

Basic Data Collection and Post-processing Depends on study area size

($0.50 -$2.50/acre for 1M – 15k acres) ~$1/acre for a 250K acre project

Raw lidar data Bare earth First surface

Basic Data Collection and Post-processing Depends on study area size

($0.50 -$2.50/acre for 1M – 15k acres) ~$1/acre for a 250K acre project

Raw lidar data Bare earth First surface

Mobilization $8k – $15k

Administration Project and flight planning Weather contingency Pre-collection tasks

Mobilization $8k – $15k

Administration Project and flight planning Weather contingency Pre-collection tasks

Advanced Processing Additional $3 – $7/acre

Canopy cover Tree height Forest biomass Other vegetation derivatives

Advanced Processing Additional $3 – $7/acre

Canopy cover Tree height Forest biomass Other vegetation derivatives

Summary Summary

Lidar is an exciting (relatively) new technology Provides measurements! Vegetation structural information are its strengths Existing research provides a strong foundation

Lidar processing requires special skills/tools Data volume can be an issue Specialized software (not just ESRI products)

required for efficient large scale analysis Lidar missions

Specifications becoming better understood Still expensive, but costs coming down Multiple resource applications & consortia allow for

cost sharing

Lidar is an exciting (relatively) new technology Provides measurements! Vegetation structural information are its strengths Existing research provides a strong foundation

Lidar processing requires special skills/tools Data volume can be an issue Specialized software (not just ESRI products)

required for efficient large scale analysis Lidar missions

Specifications becoming better understood Still expensive, but costs coming down Multiple resource applications & consortia allow for

cost sharing