2007 Aero-Metric Inc. Topographic LiDAR: Valdez, Alaska

Create custom data files by choosing data area, product type, map projection, file format, datum, etc.

Simple download of data files.

This graphic shows topographic LiDAR coverage for Valdez, Alaska.

Date that the source FGDC record was last modified.

Converted from FGDC Content Standards for Digital Geospatial Metadata (version FGDC-STD-001-1998) using 'fgdc_to_inport_xml.pl' script. Contact Tyler Christensen (NOS) for details.

Partial upload of Positional Accuracy fields only.

Partial upload to move data access links to Distribution Info.

System Calibration:

Aero-Metric collected data over a previously surveyed area in Palmer, Alaska. Data was collected at the same settings as this project, using two intersecting perpendicular lines. Two GPS ground stations were operating on site

in order to minimize GPS error. The data was classified in each line separately for ground and other common features between lines, such as building roofs. This data was processed in TerraMatch 8.001 (TerraSolid, Ltd.), to

compute corrections for roll, pitch, heading, and mirror scale. These corrections were applied to the initial processing settings (.res file). The data was reprocessed to verify the corrections were applied properly. The

corrected data was then compared to ground surveyed measurements in order to check for any consistent vertical bias. The final step in calibration verified there was minimal vertical noise due to changes in intensity. This was

done by comparing elevations of points on the airport runway, one point on a runway stripe and another adjacent point on the pavement.

Create a smoothed-best estimated trajectory (SBET) of the sensor at a rate of 200 Hz, by integrating the airborne GPS and IMU data. The basis of the GPS coordinates were computed using NGS OPUS, and were referenced to

NAD83 (CORS96) with GEOID06 derived orthometric heights. The maximum baseline distance for this project was 30 km, the average base line length was 12 km. The mean GPS positional accuracy for this project was +/- 0.08 meters.

Integrate SBET and raw laser data to produce point cloud data in LAS 1.1 format for each flight line.

Compute the roll, pitch, heading, and mirror scale correction factors for each flight line, then apply corrections to the corresponding flight line.

Automated classification of the bare-earth data from the lidar point cloud using a series of algorithms customized for the types of terrain encountered in the project.

Manual classification of any data which appears to be bare-earth but was not properly classified using the automated methods.

The shorelines of the lakes and port areas were determined using manual techniques, starting with digitized shorelines from the orthophotography of the project area. The lidar points then underwent an intensive manual

edit to determine with greater accuracy the points which represented the water surface. For the final data products the mean elevation of the water on each lake was used to determine its fixed elevation. The port areas

fixed elevation was determined using the highest water point in the port data set. This value was found to be 4.72 meters. All points below 4.72 meters in the port area were fixed to this elevation, as per the contract.

Create point clouds in LAS 1.1 format for all returns.

Data verified using survey control points, located throughout the area.

The metadata was updated for Bounding coordinates, Spatial Reference info using FGDC template

The NOAA Office for Coastal Management (OCM) received topographic files in LAS 1.1 format. The files contained lidar

elevation and intensity measurements. The data were received in projected coordinates of NAD83 UTM6N, meters

and were vertically referenced to NAVD88 orthometric elevations using GEOID06(Alaska). The vertical units of the data were

meters. OCM performed the following processing for data storage and Digital Coast provisioning purposes:

1. LAS Classifications 11(first return only), 13(first of many returns), 14(second of many returns), 15(third of many returns), 16(last of many returns) were all placed into Class 1 (Unclassified)

2. The topographic las files were converted from Projected Coordinates (NAD83 UTM6N, meters) to Geographic Coordinates (NAD83, decimal degrees).

3. The topographic las files were vertically converted from orthometric elevations (NAVD88) to ellipsoidal elevations (NAD83) using GEOID06.