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Short Citation:
OCM Partners, 2024: 2011 USGS Lidar: Orange County (CA),

Item Identification

Title: 2011 USGS Lidar: Orange County (CA)
Short Name: ca2011_usgs_orange_m4793_metadata
Status: Completed
Publication Date: 2015-01-16

LiDAR (Light Detection and Ranging) discrete-return point cloud data are available in the American Society for Photogrammetry and Remote Sensing (ASPRS) LAS format. The LAS format is a standardized binary format for storing 3-dimensional point cloud data and point attributes along with header information and variable length records specific to the data. Millions of data points are stored as a 3-dimensional data cloud as a series of x (longitude), y (latitude) and z (elevation) points. A few older projects in this collection are in ASCII format.

Acquired LiDAR data over an Area of Interest (AOI) entire of Orange County California. The acquisition plan entailed a nominal point spacing of 1.76 points per meter square and a side lap of 40% between flight lines. The AOI covers 696 square miles.


High-resolution digital elevation maps generated by airborne and stationary LiDAR have led to significant advances in geomorphology, the branch of geoscience concerned with the origin and evolution of Earth's surface topography. LiDAR provides unique characteristics relative to other remotely sensed data sources by providing three-dimensional feature information that cannot be derived from traditional imaging sensors.



Supplemental Information:

A report for this project is available at:

A footprint of this data set may be viewed in Google Earth at:

3D Breaklines are available for this dataset however NOAA has not evaluated these and therefore are only available by request.


Theme Keywords

Thesaurus Keyword
ISO 19115 Topic Category
None 3-dimensional
None Light Detection and Ranging
None point cloud
None radar

Physical Location

Organization: Office for Coastal Management
City: Charleston
State/Province: SC

Data Set Information

Data Set Scope Code: Data Set
Maintenance Frequency: As Needed
Data Presentation Form: las
Entity Attribute Overview:

LAS 1.2 format (classes 1,2,7,9,10)

Entity Attribute Detail Citation:


Distribution Liability:

Any conclusions drawn from the analysis of this information are not the responsibility of Merrick & Co, USGS, NOAA, the Office for Coastal Management or its partners.

Support Roles

Data Steward

CC ID: 671113
Date Effective From: 2015-01-16
Date Effective To:
Contact (Organization): NOAA Office for Coastal Management (NOAA/OCM)
Address: 2234 South Hobson Ave
Charleston, SC 29405-2413
Email Address:
Phone: (843) 740-1202


CC ID: 671115
Date Effective From: 2015-01-16
Date Effective To:
Contact (Organization): NOAA Office for Coastal Management (NOAA/OCM)
Address: 2234 South Hobson Ave
Charleston, SC 29405-2413
Email Address:
Phone: (843) 740-1202

Metadata Contact

CC ID: 671116
Date Effective From: 2015-01-16
Date Effective To:
Contact (Organization): NOAA Office for Coastal Management (NOAA/OCM)
Address: 2234 South Hobson Ave
Charleston, SC 29405-2413
Email Address:
Phone: (843) 740-1202

Point of Contact

CC ID: 671114
Date Effective From: 2015-01-16
Date Effective To:
Contact (Organization): NOAA Office for Coastal Management (NOAA/OCM)
Address: 2234 South Hobson Ave
Charleston, SC 29405-2413
Email Address:
Phone: (843) 740-1202


Currentness Reference: Ground Condition

Extent Group 1

Extent Group 1 / Geographic Area 1

CC ID: 1136345
W° Bound: -118.122754
E° Bound: -117.509822
N° Bound: 33.955557
S° Bound: 33.428832

Extent Group 1 / Time Frame 1

CC ID: 1136344
Time Frame Type: Range
Start: 2011-12-17
End: 2012-02-09

Spatial Information

Spatial Representation

Representations Used

Vector: Yes

Access Information

Security Class: Unclassified
Data Access Procedure:

This data can be obtained on-line at the following URL:

The data set is dynamically generated based on user-specified parameters.;

Data Access Constraints:


Data Use Constraints:

Users should be aware that temporal changes may have occurred since this data set was collected and some parts of this data may no longer represent actual surface conditions. Users should not use this data for critical applications without a full awareness of its limitations. These data depict the heights at the time of the survey and are only accurate for that time.

Distribution Information

Distribution 1

CC ID: 740525
Download URL:
File Name: Customized Download

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

Distribution 2

CC ID: 740526
Download URL:
File Name: Bulk Download

Simple download of data files.



CC ID: 740528
URL Type:
Online Resource


CC ID: 740529
URL Type:
Online Resource


CC ID: 740530
Name: Browse Graphic
URL Type:
Browse Graphic
File Resource Format: kmz

This graphic shows the lidar coverage for the 2011 lidar project covering Orange County, CA.

Activity Log

Activity Log 1

CC ID: 671136
Activity Date/Time: 2017-03-20

Date that the source FGDC record was last modified.

Activity Log 2

CC ID: 671135
Activity Date/Time: 2017-11-14

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

Activity Log 3

CC ID: 718189
Activity Date/Time: 2018-02-08

Partial upload of Positional Accuracy fields only.

Activity Log 4

CC ID: 740527
Activity Date/Time: 2018-03-13

Partial upload to move data access links to Distribution Info.

Data Quality


See survey report

Horizontal Positional Accuracy:

The ortho imagery horizontal positional accuracy and the assurance of that accuracy depend, in part, on the accuracy of the data inputs to the rectification process. These inputs consist of the digital terrain model (DTM), fully digital analytic aerotriangulation (FDAAT) control and methods, the photo source camera calibration, scanner calibration, and aerial photographs. The orthoimagery output from these inputs meet National Map Accuracy Standards (NMAS). Aerial cameras have current certification from the USGS, National Mapping Division, Optical Science Laboratory. Test calibration scans are performed on all source photography scanners.; Quantitative Value: 1.0 meters, Test that produced the value: Not Tested, see report for clarification.

Vertical Positional Accuracy:

Required to meet 0.125 m RMSE(z); Quantitative Value: 0.10 meters, Test that produced the value: Tested RMSE(z) in meters for checkpoints. FVA Computed to 0.19 m. and a CVA of 0.17 m.

Completeness Report:

The dataset was reviewed to ensure complete coverage of the project area.

Conceptual Consistency:

Completed lidar data acquisition and data calibration for the project area.


Process Steps

Process Step 1

CC ID: 1136340

LiDAR mass points were produced to LAS 1.2 specifications, including the following LAS

classification codes:

The data was processed using GeoCue and TerraScan software. The initial step is the setup of the GeoCue project, which is done by importing a project defined tile boundary index encompassing the entire project area. The acquired 3D laser point clouds, in LAS binary format, were imported into the GeoCue project and tiled according to the project tile grid. Once tiled, the laser points were classified using a proprietary routine in TerraScan. This routine classifies

any obvious outliers in the dataset to class 7 and points with scan angles exceeding +/- 20 degrees to class 11. After points that could negatively affect the ground are removed from class 1, the ground layer is extracted from this remaining point cloud. The ground extraction process encompassed in this routine 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 on low points being selected by a "roaming window" with the assumption that these are the ground points. The size of this roaming window is determined by the building size parameter. The 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. This process is repeated until no additional points are added within iterations. A second critical parameter is the maximum terrain angle constraint, which determines the maximum terrain angle allowed within the classification model. The following fields within the LAS files are populated to the following precision: GPS Time (0.000001 second precision), Easting (0.003 meter precision), Northing (0.003 meter precision), Elevation (0.003 meter precision), Intensity (integer value - 12 bit dynamic range), Number of Returns (integer - range of 1-4), Return number (integer range of 1-4), Scan Direction Flag (integer - range 0-1), Classification (integer), Scan Angle Rank (integer), Edge of flight line (integer, range 0-1), User bit field (integer - flight line information encoded). The LAS file also contains a Variable length record in the file header that defines the projection, datums, and units.

Process Date/Time: 2010-01-01 00:00:00

Process Step 2

CC ID: 1136341

Once the initial ground routine has been performed on the data, Dewberry creates Delta Z (DZ) orthos to check the relative accuracy of the LiDAR data. These orthos compare the elevations of LiDAR points from overlapping flight lines on a 1 meter pixel cell size basis. If the elevations of points within each pixel are within 10 cm of each other, the pixel is colored green. If the elevations of points within each pixel are between 10 cm and 20 cm of each other, the pixel is

colored yellow, and if the elevations of points within each pixel are greater than 20 cm in difference, the pixel is colored red. Pixels that do not contain points from overlapping flight lines are colored according to their intensity values. DZ orthos can be created using the full point cloud or ground only points and are used to review and verify the calibration of the data is acceptable. Some areas are expected to show sections or portions of red, including terrain

variations, slope changes, and vegetated areas or buildings if the full point cloud is used. However, large or continuous sections of yellow or red pixels can indicate the data was not calibrated correctly or that there were issues during acquisition that could affect the usability of the data. The DZ orthos for Orange County California showed that the data was calibrated correctly with no issues that would affect its usability. The figure below shows an example of the

DZ orthos. Dewberry utilized a variety of software suites for data processing. The LAS dataset was received and imported into GeoCue task management software for processing in Terrascan. Each tile was imported into Terrascan and a surface model was created to examine the ground classification. Dewberry analysts visually reviewed the ground surface model and corrected errors in the ground classification such as vegetation, buildings, and bridges that were present

following the initial processing conducted by Dewberry. Dewberry analysts employ 3D visualization techniques to view the point cloud at multiple angles and in profile to ensure that non-ground points are removed from the ground classification. After the ground classification corrections were completed, the dataset was processed through a water classification routine that utilizes breaklines compiled by dewberry to automatically classify hydro features. The

water classification routine selects ground points within the breakline polygons and automatically classifies them as class 9, water. The final classification routine applied to the dataset selects ground points within a specified distance of the water breaklines and classifies them as class 10, ignored ground due to breakline proximity.

Process Date/Time: 2010-01-01 00:00:00

Process Step 3

CC ID: 1136342

The NOAA Office for Coastal Management (OCM) received the files in laz format from USGS via an FTP online repository. The files contained lidar elevation and intensity measurements. The data were in UTM Zone 11 (meters) and NAVD88 (orthometric) heights in meters. OCM performed the following processing for data storage and Digital Coast provisioning purposes:

1. The data were converted from UTM coordinates to geographic coordinates.

2. The data were converted from NAVD88 (orthometric) heights in meters to GRS80 (ellipsoid) heights in feet using Geoid 09.

3. Class 11 points were reclassified to class 15 in accordance to the OCM classification scheme.

Process Date/Time: 2015-01-10 00:00:00

Catalog Details

Catalog Item ID: 49646
GUID: gov.noaa.nmfs.inport:49646
Metadata Record Created By: Anne Ball
Metadata Record Created: 2017-11-15 15:21+0000
Metadata Record Last Modified By: SysAdmin InPortAdmin
Metadata Record Last Modified: 2022-08-09 17:11+0000
Metadata Record Published: 2022-03-16
Owner Org: OCMP
Metadata Publication Status: Published Externally
Do Not Publish?: N
Metadata Last Review Date: 2022-03-16
Metadata Review Frequency: 1 Year
Metadata Next Review Date: 2023-03-16