DISTRIBUTION OF LIDAR DATA VIA THE INTERNETDISTRIBUTION OF LIDAR DATA VIA THE INTERNETMichael Hearne and Andrew Meredith

Technology Planning and Management CorporationCoastal Remote Sensing ProgramNOAA Coastal Services Center

Charleston, SC

AbstractThere are a large number of remotely sensed data sets in the public domain, but few of them are readily available or usable by the coastal resource management community. One of the goals of the NOAA Coastal Services Center is to take these data, remove the burden of data processing from the user, and create a more useful end product.

LIDAR (LIght Detection and Ranging) is a technology that creates a promising, but difficult to use, data set. The Center has a vast quantity of high-resolution topographic LIDAR data for many of the beaches within the 48 contiguous U.S. states. To distribute this data to as many people with differing technological capabilities as possible, we developed the LIDAR DAta Retrieval Tool (LDART). LDART utilizes various web technologies that allow users to select data from specific areas and to define the final output product. The user can specify geographic projections, datums, and file formats. By providing this LIDAR data via the Internet, the Center aims to help coastal resource managers make environmentally sound, scientifically defensible policy decisions.

Parameter Options ConsiderationsSpatial Extent N/A Due the high density of the data points, choose as small an area as possibleDate(s) ofsurvey

N/A Submit a single LDART request for each survey date to create individual datasets by day

Horizontaldatum

ITRF94, NAD83,NAD27

Choose horizontal datum to match other spatial dataNAD83 is the most common datum

Vertical datum Ellipsoid, NAVD88,NGVD29

Choose vertical datum to match other vertical dataNAVD88 and NGVD29 are "mean sea level" datums

Vertical units Feet, meters Choose units to match other vertical dataProjection Geographic, UTM,

State Plane 1983,State Plane 1927

Choose projections to match other spatial data or local regulations

Binningmethod

None, Smoothed,Averaged, Minimum,Maximum

Choose None for access to point dataChoose Smoothed for contoursChoose Averaged, Minimum, or Maximum depending on type of surfacerequired

Cell Size Feet, Meters Minimum cell size should be 2 metersSelect cell size appropriate for feature identification

File format x,y,z Points, BinaryRaster File, GeoTiff

Choose x,y,z points for access to ASCII point dataChoose binary raster file for GIS analysisChoose GeoTiff for viewing

What Is LIDAR?

• A remote sensing technology used to collect topographic data. • Data collected via a partnership with NASA and the USGS, using an instrument called the Airborne Topographic Mapper.• Data with a vertical accuracy of + 20 centimeters.

What Is LDART?

World Wide Web based LIDAR data selection tool created for:

• extracting data for a specific geographic area• defining a high-resolution digital elevation data set

Why Was It Created?

A LIDAR data set of appreciable size contains hundreds of thousands of individual elevation measurements e.g., 320,000 individual measurements over a one-kilometer beach section. LDART was developed to remove the burden of data processing from the coastal manager,allowing them to:

•create a more usable data product than the raw x,y,z points•easily incorporate this remote sensing data into a GIS•create small, manageable data sets in a particular region of interest

How Can I Define My LIDAR Data Set?

The LDART User Interface allows user to define various options (Table 1):

Select geographic boundaries

Select state and period of interest

Select survey date(s)

Conclusions

Topographic LIDAR data is being used for determining regulatory setback lines, and for identifying habitat for endangered beach plants. It has also been used to quantify sand volume changes on beaches in North Carolina, assess impacts from El Niño on the U.S. West Coast, and investigate variations in shoreline response to different storm events. Anyone interested in working with a high-resolution digital elevation model in coastal regions should investigate this data source. LDART can deliver GIS-ready remotely sensed data to anyone with a browser and a reasonably fast connection to the Internet, and the addition of GeoTiff as an output format allows those who are not as knowledgeable about GIS or remote sensing see the types of information that LIDAR can provide.

LDART can be found at the following web address: http://www.csc.noaa.gov/ldart

Step 1: Enter user information

Step 2: Define spatial bounds and survey dates

Step 3: Select product options

Where Was Data Collected?

Since the Fall of 1996, the Center in partnership with NASA and USGS has surveyed over 6100 kilometers of U.S. coastline. Table 2 shows the breakdown of LIDAR data collection by region and year.

What Can I Do with the Data?

All of the above images are shaded relief maps of LIDAR, created using ArcView® Spatial Analyst. In each case, blue represents lower elevations, while red represents high. From the left:

•Pillar Point, south of San Francisco, CA.

Getting the Data

Examples of binning methods

Example of x,y,z point data

Table 1. LDART parameters and options.

Table 2. LIDAR survey coverage

Year Region Coverage (km)1996 East Coast ~6001997 East Coast ~1,2001997 West Coast ~1,0001998 East Coast ~1,3001998 West Coast ~1,0001998 Gulf Coast ~1,2001999 East Coast ~1,000