Transcript UNDERSTANDING LiDAR Light Detection and Ranging

UNDERSTANDING LIDAR
LIGHT DETECTION AND RANGING
LIDAR is a remote
sensing technique that
can measure the distance
to objects on and above
the ground surface by
illuminating the targets
with a laser light and
analyzing the
backscattered light.
• LIDAR produces High
accurate x,y,z
measurements
•
TYPES OF LIDAR
• Airborne
Airplanes and helicopters are used
to acquire data over broad areas.
The majority of these platforms
cover about 50 kilometers per
hour with a high accuracy level.
Airborne LIDAR systems are the
most
commonly used for generating
DEM (Digital Elevation Models).
• Ground based
Offers a street perspective and can
be mounted in cars, boats, trucks,
tripods or trains. Is great for
smaller areas where higher density
is required.
IMPORTANT THINGS TO KNOW
ABOUT LIDAR
• Point spacing of your LIDAR Data
Refers to how close the laser points are to each other. This is important because the
point spacing determines the resolution of derived products. If you want to create
building footprints you need at least 1 meter spacing.
• Type of files supply with your LIDAR
LAS files or ASCII
Intensity images
Raster files (DEM)
Metadata
• QA and QC of your data
Completeness of data (LAS files, intensity images, etc)
Comparison of elevations among different deliverables
• Classification of your data. How many classes does your LAS point data contain?
Every point of your LIDAR has a classification assigned to it that defines the type of
object and its correspondent reflected laser pulse. These classifications are defined
using numeric integer codes.
IMPORTANT THINGS TO KNOW
ABOUT LIDAR
The SC Consortium Project uses the following classification:
The ESRI LAS 1.1 standard use this classification:
IMPORTANT THINGS TO KNOW
ABOUT LIDAR
• Understanding Returns
The laser pulse emitted from a LIDAR system reflects from objects on and above the
ground surface. A laser pulse can return to the LIDAR system as one or many returns.
The first return includes the buildings, tree canopy and is referred to a DSM (Digital
Surface Model). The last return or bare earth surface contains only the topography and
is called a DEM (Digital Elevation Model).
SOFTWARE YOU NEED TO INTERACT
WITH LIDAR
The Data derivatives and analysis you can perform from LIDAR mainly depends on the
software and type of data you have.
Stand-alone applications
Quick Terrain Modeler (Applied Imagery)
MARS Explorer/Explorer Pro (Merrick)
LAS Tools (free) http://www.cs.unc.edu/~isenburg/lastools/
ArcGIS extensions
LIDAR Analyst (Visual Learning Systems)
LP360 (QCoherent)
3D Analyst
SOFTWARE YOU NEED TO INTERACT
WITH LIDAR
ArcGIS 10.1
Supports the following datasets:
• Terrain dataset 9.2
• Mosaic datasets 10
• LAS datasets 10.1
SOFTWARE YOU NEED TO
INTERACT WITH LIDAR
ArcGIS 10.1
ARCSCENE 10.1
ARC GIS 10.1
PROFILE VIEW EDITING
3D WINDOW ARC GIS 10.1
SOFTWARE YOU NEED TO
INTERACT WITH LIDAR
LIDAR APPLICATIONS & USES
Contour Maps
Land Slip Risk Assessment
Bathymetric
Biomass Study
Mining
Corridor and Quarrying
Flood Analysis
Hydrology
Seismic Hazards
Pipeline Surveys
Highways
Railways
Infrastructure Design
Environmental Planning
Engineering Planning
Telecommunications
City Models
Electricity and Transmission lines
CONTOURS
HYDROLOGY
DESIGN
PLANNING
LIDAR APPLICATIONS & USES
DEM
DSM
CITY MODELS
3D VIEWS
RASTERS
ACCESING LIDAR
•
•
•
•
SC DNR http://www.dnr.sc.gov/GIS/lidarcounty.html
NOAA http://www.csc.noaa.gov/digitalcoast/data/coastallidar/index.html
USGS http://lidar.cr.usgs.gov/
OPEN TOPOGRAPHY http://opentopo.sdsc.edu/gridsphere/gridsphere?cid=datasets
LIDAR TRAINING
• NOAA http://www.csc.noaa.gov/digitalcoast/training/intro-lidar
• ESRI
CONCLUSION
In conclusion, processing large amounts of LIDAR points can be time consuming,
no matter what method or software you use. It is important to take into account
considerations such as: point density of your LIDAR points, desired resolution of
rasters, and extent of project.
Analyzing these considerations will help you come up with a plan to process
LIDAR data.