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Topographic Lidar Survey: South San Francisco Bay, CA

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Metadata:


Identification_Information:
Citation:
Citation_Information:
Originator:
United States Geological Survey (USGS) and the California Coastal Conservancy (CCC)
Publication_Date: 2005
Title: Topographic Lidar Survey: South San Francisco Bay, CA
Geospatial_Data_Presentation_Form: map
Larger_Work_Citation:
Citation_Information:
Originator: Bruce Jaffe
Publication_Date: 2005
Title: Topographic Lidar Survey: South San Francisco Bay, CA
Series_Information:
Series_Name: Scientific Investigation Map
Issue_Identification: 2007-XXXX
Publication_Information:
Publication_Place: Menlo Park, CA
Publisher: U.S. Geological Survey, Coastal and Marine Geology Program
Online_Linkage: <http://pubs.wr.usgs.gov/sim/2007/XXXX/>
Description:
Abstract:
The California Coastal Conservancy, in conjunction with other state and federal agencies, is collaboratively managing an effort to restore approximately 61 km2 (15,100 acres) of commercial salt evaporation ponds in South Bay to mixed intertidal habitat. In order to best develop restoration strategies, as well as to track morphologic change throughout the restoration process, a topographic lidar survey was conducted in May of 2004. The survey collected more than 250 million elevation points in a 334 km2 area extending from just south of the San Francisco and Oakland airports to the Alviso salt ponds.
Purpose:
The purpose of the lidar mapping was to provide a high quality DEM for drainage mapping and salt pond restoration for the USGS.
Supplemental_Information:
Information for USGS Coastal and Marine Geology related activities are online at <http://walrus.wr.usgs.gov/infobank/f/f204sf/html/f-2-04-sf.meta.html>.
Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 20040505
Ending_Date: 20040521
Currentness_Reference: ground condition
Status:
Progress: Complete
Maintenance_and_Update_Frequency: As needed
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate: -122.0
East_Bounding_Coordinate: -121.0
North_Bounding_Coordinate: 38.0
South_Bounding_Coordinate: 37.0
Keywords:
Theme:
Theme_Keyword_Thesaurus: General
Theme_Keyword: marine geology
Theme_Keyword: topography
Theme_Keyword: bathymetry
Theme_Keyword: lidar
Theme_Keyword: water depth
Theme_Keyword: ocean floor topography
Theme_Keyword: elevation
Theme_Keyword: U.S. Geological Survey
Theme_Keyword: USGS
Theme_Keyword: Coastal and Marine Geology Program
Theme_Keyword: CMGP
Theme:
Theme_Keyword_Thesaurus: ISO 19115 Topic Category
Theme_Keyword: oceans and estuaries
Theme_Keyword: imageryBaseMapsEarthCover
Theme:
Theme_Keyword_Thesaurus: Global Change Master Directory (GCMD)
Theme_Keyword: EARTH SCIENCE > OCEANS > BATHYMETRY/SEAFLOOR TOPOGRAPHY
Theme_Keyword:
Instruments > Earth Remote Sensing Instruments > Active Remote Sensing > Altimeters > Lidar/Laser Altimeters
Place:
Place_Keyword_Thesaurus: General
Place_Keyword: South San Francisco Bay
Place_Keyword: CA
Place_Keyword: Northern California
Place_Keyword: USA
Place:
Place_Keyword_Thesaurus: Geographic Names Information System (GNIS)
Place_Keyword: San Francisco Bay
Place_Keyword: California
Access_Constraints: None
Use_Constraints:
Public domain data from the U.S. government is freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey (USGS) and the California Coastal Conservancy (CCC) as the source of this information.
Point_of_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Bruce Jaffe
Contact_Organization: U.S. Geological Survey, Coastal and Marine Geology
Contact_Position: Oceanographer
Contact_Address:
Address_Type: mailing and physical address
Address: 400 Natural Bridges Dr
City: Santa Cruz
State_or_Province: CA
Postal_Code: 95060-5792
Country: USA
Contact_Voice_Telephone: (831) 427-4742
Contact_Facsimile_Telephone: (831) 427-4748
Contact_Electronic_Mail_Address: bjaffe@usgs.gov

Data_Quality_Information:
Logical_Consistency_Report: Unspecified
Completeness_Report: Complete
Positional_Accuracy:
Horizontal_Positional_Accuracy:
Horizontal_Positional_Accuracy_Report: +/- 20 - 60 centimeters on all but extremely hilly terrain.
Vertical_Positional_Accuracy:
Vertical_Positional_Accuracy_Report:
+/- 10-15 centimeters on Hard Surfaces (roads and buildings), +/- 15-25 centimeters on Soft/Vegetated Surfaces (flat to rolling terrain), +/- 25-40 centimeters on Soft/Vegetated Surfaces (hilly terrain)
Lineage:
Process_Step:
Process_Description:
The topographic lidar data was collected by TerraPoint USA from May 5 to 21, 2004. Twenty-five flights were required to cover the project area with approximately one hundred thirty six flight lines. The control network and check point surveys were established from April 30 to May 20, 2004. Boresight correction, vegetation removal and product generation took place from June 3 to October 27, 2004.

The GPS and inertial data were processed in tandem to achieve the best positional result. Once the position and attitude of the aircraft were known at each epoch (1-second intervals), then these data were integrated with the laser ranges to provide a position for each data point on the ground. The data were then processed using TerraPoint's proprietary laser processing software suite to produce coordinates. Each flight involved setting up two base stations to collect data. Utilizing two base stations ensures GPS data collection in the event that the main base station fails. For all flights the GPS data were of high quality. This minimized the absolute error for the aircraft position. The primary quality control tool for the laser ranges is the percentage of returns that are received back at the laser after it has emitted a signal. The acceptable range for returns, typically between 90% and 95% was met for this project. Lower percentages are normal over water and other poor reflectivity surfaces such as the dark, wet surfaces typical of the project area's mud flats.

The points are generated as Terrascan binary Format using Terrapoint's proprietary Laser Postprocessor Software. This software combines the Raw Laser file and GPS/IMU information to generate a point cloud for each individual flight.

All the point cloud files encompassing the project area were then divided into 2 kilometer by 2-kilometer tiles. The referencing system of these tiles is based upon the project boundary minimum and maximums. This process is carried out in Terrascan.

The bald earth is subsequently extracted from the raw LiDAR points using Terrascan in a Microstation environment. The automated vegetation removal process takes place by building an iterative surface model. This surface model is generated using three main parameters: Building size, Iteration angle and Iteration distance.

The initial model is based upon low points selected by a roaming window and are assumed to be ground points. The size of this roaming window is determined by the building size parameter. These low points are triangulated and the remaining points are evaluated and subsequently added to the model if they meet the Iteration angle and distance constraints (fig. 1). This process is repeated until no additional points are added within an iteration.

There is also a maximum terrain angle constraint that determines the maximum terrain angle allowed within the model.

Once the data setup has taken place the manual quality control of the surface occurs. This process consists of visually examining the LiDAR points within Terrascan and correcting errors that occurred during the automated process. These corrections include verifying that all non ground elements, such as vegetation and buildings are removed from the ground model and that all small terrain undulations such as road beds, dykes, rock cuts and hill tops are present within the model.

This process is done with the help of hillshades, contours, profiles and crosssections. To correct misclassifications, a full suite of Terrascan and custom in-house data tools are used.

The above description is taken from the TerraPoint USA Project Report: USGS - South Bay Restoration Project, Contract #2206-H

Process_Date: 20041027
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Bruce Jaffe
Contact_Organization: U.S. Geological Survey, Coastal and Marine Geology
Contact_Position: Oceanographer
Contact_Address:
Address_Type: mailing and physical address
Address: 400 Natural Bridges Dr
City: Santa Cruz
State_or_Province: CA
Postal_Code: 95060-5792
Country: USA
Contact_Voice_Telephone: (831) 427-4742
Contact_Facsimile_Telephone: (831) 427-4748
Contact_Electronic_Mail_Address: bjaffe@usgs.gov


Spatial_Data_Organization_Information:
Direct_Spatial_Reference_Method: Raster
Raster_Object_Information:
Raster_Object_Type: Point


Spatial_Reference_Information:
Horizontal_Coordinate_System_Definition:
Planar:
Grid_Coordinate_System:
Grid_Coordinate_System_Name: Universal Transverse Mercator
Universal_Transverse_Mercator:
UTM_Zone_Number: 10
Transverse_Mercator:
Scale_Factor_at_Central_Meridian: 0.9996
Longitude_of_Central_Meridian: -123.00000
Latitude_of_Projection_Origin: 0.00000
False_Easting: 0.00
False_Northing: 0.00
Planar_Coordinate_Information:
Planar_Coordinate_Encoding_Method: coordinate pair
Coordinate_Representation:
Abscissa_Resolution: 1.0
Ordinate_Resolution: 1.0
Planar_Distance_Units: Meters
Geodetic_Model:
Horizontal_Datum_Name: North American Datum of 1983
Ellipsoid_Name: NAVD88
Semi-major_Axis: 6378137.00
Denominator_of_Flattening_Ratio: 0.003352811


Entity_and_Attribute_Information:
Overview_Description:
Entity_and_Attribute_Overview:
All LiDAR Data Products were delivered on DVD-ROM. Three copies were provided. All products other than hill-shade data were provided in 1k and 2k tiles with a 25-meter buffer. Hill-shades were delivered in three large areas.

Full Feature or All Return Point Data

Data delivered in ASCII, comma delimited files with one record per return containing data columns. The records are ordered sequentially according to Easting with no duplicate records. The individual returns are classified into the following categories: ground or water, above ground (low), above ground (high), building and NADIR. This ASCII product was generated using an in house custom utility. The process involved extracting a Terrascan Binary file packed with the scan angle and the extra precision required for the for a unique time stamp.

Bare Earth Point Data

Data delivered in ASCII, comma delimited files with one record per return containing data columns as defined in Table 4. The records are ordered sequentially according to Easting with no duplicate records. This product is a subset of the full feature or all return point data product containing only code 3, ground points, as described in table 5 below. This ASCII product was generated using an in house custom utility. The process involved extracting a Terrascan Binary file packed with the scan angle and the extra precision required for the for a unique time stamp.

The above description is taken from the TerraPoint USA Project Report: USGS - South Bay Restoration Project, Contract #2206-H

Entity_and_Attribute_Detail_Citation: none


Distribution_Information:
Distributor:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: San Francisco Estuary Institute
Contact_Address:
Address_Type: mailing and physical address
Address: 7770 Pardee Lane
City: Oakland
State_or_Province: CA
Postal_Code: 94621-1424
Country: USA
Contact_Voice_Telephone: (510) 746-7361
Distribution_Liability:
These data not intended for navigational purposes.

Although these data have been used by the U.S. Geological Survey, U.S. Department of the Interior, these data and information are provided with the understanding that they are not guaranteed to be usable, timely, accurate, or complete. Users are cautioned to consider carefully the provisional nature of these data and information before using them for decisions that concern personal or public safety or the conduct of business that involves substantial monetary or operational consequences. Conclusions drawn from, or actions undertaken on the basis of, such data and information are the sole responsibility of the user.

Neither the U.S. Government nor any agency thereof, nor any of their employees, contractors, or subcontractors, make any warranty, express or implied, nor assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any data, software, information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights.

Trade, firm, or product names and other references to non-USGS products and services are provided for information only and do not constitute endorsement or warranty, express or implied, by the USGS, USDOI, or U.S. Government, as to their suitability, content, usefulness, functioning, completeness, or accuracy.


Metadata_Reference_Information:
Metadata_Date: 20070821
Metadata_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey, Coastal and Marine Geology
Contact_Person: Peter Dartnell
Contact_Position: Physical Scientist
Contact_Address:
Address_Type: mailing and physical address
Address: 345 Middlefield Rd MS-999
City: Menlo Park
State_or_Province: CA
Postal_Code: 94025-3561
Country: USA
Contact_Voice_Telephone: (650) 329-5460
Contact_Facsimile_Telephone: (650) 329-5411
Contact_Electronic_Mail_Address: pdartnell@usgs.gov
Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata
Metadata_Standard_Version: FGDC-STD-001-1998

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