Embed Size (px)
DESCRIPTION
Data Discovery Day 03/06/2008 Craig Clouet ESRI
Citation preview
HIGICC – Data Discovery Day
Craig Clouet & Mathew BarbeeHonolulu, Hawaii
2008
LiDARLiDAR::What it is,What it is,
How to use itHow to use itWhere to get itWhere to get it
Agenda
• What is LiDAR – Craig Clouet– Types– Data collection & storage
• LiDAR Applications – Matt Barbee UH
• LiDAR Data Availability – Craig Clouet
Hand-held Laser technology
– LiDAR stands for Light Detection and Ranging. The system is mounted in an aircraft and is comprised of three primary components:
– Laser - collects 50 thousand pulse points per second and records a measurement approximately every 1.5 feet
– IMU – a military grade inertial navigation system which measures the movement of the aircraft in three axis 250 times per second.
• Kinematic GPS – Receivers log raw data at one second intervals both on the ground and on the aircraft providing extremely precise positioning every one second.
Three Main Types of Commercial LiDAR Systems
Topographic Mapping
SHOALS
Terrestrial
Topographic Mapping
The LiDAR Set-up
Portable for Shipping & multiple Platforms
SHOALS
Terrestrial
The terrestrial LIDAR technique, or 3D laser scanning as it is commonly known, consists of sending and receiving laser pulses to build a point file of three-dimensional coordinates of virtually any surface. The time of travel for a single pulse reflection is measured along a known trajectory such that the distance from the laser, and consequently the exact location of a point of interest can be computed. In addition, some lasers use a color sensor to obtain additional visual data on points located both within and outside of laser range. Given the rapid rate of data collection from the newest state of the art topographic laser scanning systems, the location of up to 12,000 surface points can be collected in one second. Thus, an entire surface, be it a building, a cliff face, or a sand bar can be surveyed quickly and accurately. The point file from a given scan is typically transformed into a three-dimensional surface so that cross-sections and volumetric calculations can be performed between consecutively scanned surfaces.
Data Structureand
Uses of the Elevations
LiDARPointCloud
LiDARpoint spacingDetermined at Contract
DEM spacingCreated by user
Level ofAccuracy and Interpolation
Example of the Grid Spacing at 5ft
Elevations at each 5 ft cell
The Point Cloud
Lots of actual data measurementsNot too much Interpolation
File Formats
E N Z I
Or ENZI
LAS Format
The LAS file format is a public file format for the interchange of LIDAR data between vendors and customers. This binary file format is a alternative to proprietary systems or a generic ASCII file interchange system used by many companies. The problem with proprietary systems is obvious in that data cannot be easily taken from one system to another.
There are two major problems with the ASCII file interchange. The first problem is performance because the reading and interpretation of ASCII elevation data can be very slow and the file size can be extremely large, even for small amounts of data. The second problem is that all information specific to the LIDAR data islost. The LAS file format is a binary file format that maintains information specific to the LIDAR nature of the data while not being overly complex.
DigitalElevationModels
A method to Store Continuous Topographic data
Raster
Shaded Relief
A visual graphicRepresentation of topography
Contours
Graphical Representationof elevation
Vector format
Accuracy1 National Geodetic Survey, Retrieval Date = JANUARY 13, 2006TU0562 ***********************************************************************TU0562 DESIGNATION - BATH RM 3TU0562 PID - TU0562TU0562 STATE/COUNTY- HI/HONOLULUTU0562 USGS QUAD - KAENA (1983)TU0562TU0562 *CURRENT SURVEY CONTROLTU0562 ___________________________________________________________________TU0562* NAD 83(1993)- 21 34 39.91926(N) 158 15 46.06795(W) ADJUSTED TU0562* LOCAL TIDAL - 2.674 (meters) 8.77 (feet) ADJ UNCH TU0562 ___________________________________________________________________TU0562 EPOCH DATE - 1993.62TU0562 LAPLACE CORR- 4.63 (seconds) DEFLEC99TU0562 GEOID HEIGHT- 14.90 (meters) GEOID99TU0562TU0562 HORZ ORDER - SECONDTU0562 VERT ORDER - FIRST CLASS IITU0562TU0562.The horizontal coordinates were established by classical geodetic methodsTU0562.and adjusted by the National Geodetic Survey in December 1998.TU0562.The horizontal coordinates are valid at the epoch date displayed above.TU0562.The epoch date for horizontal control is a decimal equivalenceTU0562.of Year/Month/Day.TU0562TU0562.The orthometric height was key entered from printed documentsTU0562.and not key verified.
Location of NGS Reference Sites
Comparison ofNGS Elevation andLiDAR Reported Values in Feet
10 Foot Radius from Control point
Lidar Products
• Example of Airborne 1 deliverables
Bare Earth
Extracted Feature
Bare Earth
Extracted Feature
Vegetation Response
Soil State and Moisture
Using the Intensity Return
Examples
Tile Structure
Data is in Geographic Coordinates
Issues
• Clouds
• No Data
• Resolution
• Vegetation
• Interpolation of point features
No Data
Interpolation Effects
Resolution
Vegetation
Point Features
Management of data
Limitations
• Large data sets• Time to process• Requires extra software
•Ability to store in original spacing and use where and when as needed.
Tools
• ArcGIS works with LiDAR, at the 9.2 release the tools are more robust and easier to use.
• There are many other 3rd party and stand alone software solutions. Some free and some commercial.
LiDAR Tools
LiDAR Tools
LiDAR Tools
Applications
Matthew Barbee
LiDAR Resources
Coverage in Hawaii
Coverage in Hawaii
NGA - USGS
USGS
State
State
State
State
1. LIDAR data acquired for local agencies (ie. they paid for the data)Hawaii north shorelines Kauai, Oahu, Big Island, Maui, Molokai up to 15 meter elevation (Hawaii State Civil Defense)Guam topo and bathymetric LIDAR(Guam Department of Homeland Security, Guam DPW)Saipan topo(CNMI EMO, CNMI CRMO, CNMI DPW)
2. Saipan completed. Guam to be completed in March.Hawaii products to start being delivered in late March.
3. Concern from military about raw LIDAR data.Corps will not distribute data, it will need to be released by customers.
USACE ‘s message
LiDAR Data Resources
People to contact
Benton ChingUSACE Fort Shafter"Ching, Benton Y POH" <[email protected]>
Henry B. WolterUSGS Geospatial Liaison, Hawaii and Pacific Basin IslandsNSDI Partnership Office677 Ala Moana Blvd Suite 415Honolulu, Hawaii 96813808-587-2409808-282-8995(cell)[email protected]
Craig TasakaOffice of Planning, GIS ProgramPhone: (808) 587-2895Fax: (808) 587-2899Email: [email protected]
MahaloMatt BarbeeSOESTUniversity of HawaiiMatthew [[email protected]]
Craig ClouetESRI Honolulu Office1357 Kapiolani Blvd Suite 1110Honolulu, Hawaii 96814(808) - [email protected]
HIGICC
![Point Density Evaluation of Airborne LiDAR Datasets · variable mission costs [Saylam, 09]. The expected point density of LiDAR scanning is mainly dependent on mission plan parameters](https://img.pdfslide.net/doc/110x75/5ae190957f8b9a097a8bd8ad/point-density-evaluation-of-airborne-lidar-mission-costs-saylam-09-the-expected.jpg)
