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Topographic Data Development (Lidar acquisition and processing) for Hinds County, MS
Topographic Data Development (Lidar acquisition and processing) for Hinds County, MS
FGDC Metadata
Description Spatial Data Structure Data Quality Data Source Data Distribution Metadata
+ Resource Description
Citation
Information used to reference the data.
Title: Topographic Data Development (Lidar acquisition and processing) for Hinds County, MS
Originators: EarthData International, Inc.
Publication date: 20070115
Data type: map
Description
A characterization of the data, including its intended use and limitations.
Abstract:
This metadata record describes the acquisition and
processing of bare earth lidar data, raw point cloud lidar
data, lidar intensity data, and floodmap breaklines
consisting of a total of 203 sheets for Hinds County, MS.
The post-spacing for this project is 4-meter.  This project
was tasked by Mississippi Geographic Information,
LLC (MGI); Work Order No. ED-6.  EarthData International,
Inc. is a member of MGI and was authorized to undertake
this project in accordance with the terms and conditions of
the Professional Services Agreement between MGI and
the Mississippi Department of Environmental Quality
(MDEQ), dated February 17, 2004, and in accordance with
MGI Task Order No. 18a.
Purpose:
The acquisition, processing, and delivery of bare earth
lidar data, raw point cloud lidar data, lidar intensity data,
and floodmap breaklines covering Hinds County, MS was
a coordinated effort between EarthData International, Inc.
and MGI, LLC  to support MDEM and FEMA flood
mapping requirements. Floodmap breaklines are
intended to support DFIRM modeling and update only,
and will be delivered to MDEQ for use on the DFIRM
program.
Point Of Contact
Contact information for the individual or organization that is knowledgeable about the data.
Organization: EarthData International, Inc.
Person: Becky Jordan
Position: Project Manager
Phone: 301-948-8550 x121
Fax: 301-963-2064
Email: bjordan@earthdata.com
Hours of service: Monday through Friday, 8:30am to 5:00pm
Address type: mailing and physical address
Address:
7320 Executive Way
City: Frederick
State or Province: MD
Postal code: 21704
Country: USA
Data Type
How the data are represented, formatted and maintained by the data producing organization.
Data type: map
Time Period of Data
Time period(s) for which the data corresponds to the currentness reference.
Date: 20070115
Currentness reference:
Publication Date
Status
The state of and maintenance information for the data.
Data status: Complete
Update frequency: Unknown
Key Words
Words or phrases that summarize certain aspects of the data.
Theme:
Keywords: lidar, DEM, Topographic, bare earth, intensity image, LAS, ASCII, raw point cloud, floodmap breaklines
Keyword thesaurus: EDI Thesaurus
Place:
Keywords: EarthData International, Inc., Hinds County, Mississippi, USA
Keyword thesaurus: Geographic Names Information System
Data Access Constraints
Restrictions and legal prerequisites for accessing or using the data after access is granted.
Access constraints:
None
Use constraints:
None
+ Spatial Reference Information
Horizontal Coordinate System
Reference system from which linear or angular quantities are measured and assigned to the position that a point occupies.
Coordinate System Details
Grid coordinate system
Grid coordinate system name: State Plane Coordinate System 1983
State Plane Coordinate System:
SPCS xone identifier: 2302
Transverse Mercator:
Scale factor at central meridian: 0.999950
Longitude of central meridian: -090.333333
Latitude of projection origin: +29.500000
False easting: 2296583.333333
False northing: 0.000000
Planar Coordinate Information
Planar coordinate encoding method: coordinate pair
Coordinate representation:
Abscissa resolution: 13.12332
Ordinate resolution: 13.12332
Planar distance units: Survey Feet
Geodetic model
Horizontal datum name: North American Datum of 1983
Ellipsoid name: Geodetic Reference System 80
Semi-major axis: 6378137.000000
Denominator of flattening ratio: 298.257222
Vertical Coordinate System
Reference system from which vertical distances (altitudes or depths) are measured.
Altitude system definition:
Altitude datum name: North American Vertical Datum of 1988
Altitude resolution: .65
Altitude distance units: Feet
Altitude encoding method: Implicit coordinate
Spatial Domain
The geographic areal domain of the data that describes the western, eastern, northern, and southern geographic limits of data coverage.
Bounding Coordinates
In Unprojected coordinates (geographic)
Boundary Coordinate
West -90.737872 (longitude)
East -90.036490 (longitude)
North 32.601207 (latitude)
South 32.039824 (latitude)
+ Data Structure and Attribute Information
Overview
Summary of the information content of the data, including other references to complete descriptions of entity types, attributes, and attribute values for the data.
Direct spatial reference method: Point
+ Data Quality and Accuracy Information
General
Information about the fidelity of relationships, data quality and accuracy tests, omissions, selection criteria, generalization, and definitions used to derive the data.
Logical consistency report:
Compliance with the accuracy standard was ensured by
the placement of GPS ground control after the acquisition
1. The ground control and airborne GPS data stream were
validated through a fully analytical boresight adjustment.
2. The digital terrain model (DTM) data were checked
against the project control.
3. Lidar elevation data was validated through an
inspection of edge matching  and visual inspection for
quality (artifact removal).
Completeness report:
1. EarthData's proprietary software, Checkedb, for
verification against ground survey points.
2. Terrascan, for verification of automated and manual
editing and final QC of products.
Cloud cover: 0
Attribute Accuracy
Accuracy of the identification of data entities, features and assignment of attribute values.
Attribute accuracy report:
Airborne lidar data was acquired at an altitude of 9,500'
(2896 m) above mean terrain with a swath width of 7870.12
ft (2398.82 m), which yields an average post spacing of
lidar points of no greater than 13.12 ft (4 m). The project
was designed to achieve a vertical accuracy of the lidar
points at 7.28 in (18.5 cm) root mean square error (RMSE).
Positional Accuracy
Accuracy of the positional aspects of the data.
Horizontal accuracy report:
The lidar data fully comply with FEMA guidance as
published in Appendix A, April, 2003.
Vertical accuracy report:
The lidar data fully comply with FEMA guidance as
published in Appendix A, April 2003.  When compared
to GPS survey grade points in generally flat
non-vegetated areas, at least 95% of the positions have
an error less than or equal to 37 cm (equivalent to root
mean square error of 18.5 cm if errors were normally
distributed).
+ Data Source and Process Information
Data Sources
Information about the source data used to construct or derive the data.
Data source information
Aerial Lidar Acquisition
Title: Aerial Acquisition of Lidar Data for Hinds County, MS
Originators: EarthData International, Inc. (Aviation Division)
Publication date: 20060412 Publication time: Unknown
Edition: 1
Data type: model
Media: firewire
Source contribution:
MGI requested the collection of lidar data over Hinds
County, MS. In response EarthData International, Inc.
acquired the data on April 11 and 12, 2006 using its aircraft
with tail number N62912.  Lidar data was captured using
an ALS50 lidar system, including an inertial measuring unit
(IMU) and a dual frequency GPS receiver.  An additional
GPS receiver was in constant operation over a temporary
control point set by EarthData International, Inc. at
Hawkins Airport which was later tied into a local network
by Waggoner Engineering, Inc..   During the data
acquisition, the receivers collected phase data at an
epoch rate of 1 Hz.  The solution from Hinds County, MS
was found to be of high integrity and met the accuracy
requirements for the project. These accuracy checks also
verified that the data meets the guidelines outlined in
FEMA's Guidelines and Specifications for Flood Hazard
Mapping Partners and Appendix A, section 8, Airborne
Light Detection and Ranging (LIDAR) Surveys.
Airspeed - 160 knots
Laser Pulse Rate - 32900 kHz
Field of View - 45 degrees
Scan Rate - 18 Hz
Date: 20060411
Date: 20060412
Currentness reference:
Ground Condition
Ground Control
Title: Hinds County, Mississippi - Lidar Control
Originators: Waffoner Engineering, Inc.
Publication date: 20060918
Edition: 1
Data type: diagram
Media: electronic mail system
Source contribution:
Waggoner Engineering, Inc., under contract to EarthData
International, Inc. successfully established ground control
for Hinds County, MS.  A total of 16 ground control points in
Hinds County, MS were acquired.  GPS was used to
establish the control network.  The horizontal datum was
the North American Datum of 1983 (NAD83).  The vertical
datum was the North American Vertical Datum of 1988
(NAVD88).
Date: 20060918
Currentness reference:
Ground Condition
Process Steps
Information about events, parameters, tolerances and techniques applied to construct or derive the data.
Process step information
Process Step 1
Process description:
EarthData has developed a unique method for
processing lidar data to identify and remove elevation
points falling on vegetation, buildings, and other
aboveground structures.  The algorithms for filtering data
were utilized within EarthData's proprietary software and
commercial software written by TerraSolid.  This software
suite of tools provides efficient processing for small to
large-scale, projects and has been incorporated into ISO
9001 compliant production work flows. The following is a
1. The technician performs calibrations on the data set.
2. The technician performed a visual inspection of the
data to verify that the flight lines overlap correctly. The
technician also verified that there were no voids, and that
the data covered the project limits. The technician then
selected a series of areas from the data set and
inspected them where adjacent flight lines overlapped.
These overlapping areas were merged and a process
which utilizes 3-D Analyst and EarthData's proprietary
software was run to detect and color code the differences
in elevation values and profiles. The technician reviewed
these plots and located the areas that contained
systematic errors or distortions that were introduced by the
lidar sensor.
3. Systematic distortions highlighted in step 2 were
removed and the data was re-inspected.  Corrections and
adjustments can involve the application of angular
deflection or compensation for curvature of the ground
surface that can be introduced by crossing from one type
of land cover to another.
4. The lidar data for each flight line was trimmed in batch
for the removal of the overlap areas between flight lines.
The data was checked against a control network to
ensure that vertical requirements were maintained.
Conversion to the client-specified datum and projections
were then completed. The lidar flight line data sets were
then segmented into adjoining tiles for batch processing
and data management.
5. The initial batch-processing run removed 95% of points
falling on vegetation.  The algorithm also removed the
points that fell on the edge of hard features such as
structures, elevated roadways and bridges.
6. The operator interactively processed the data using
lidar editing tools.  During this final phase the operator
generated a TIN based on a desired thematic layers to
evaluate the automated classification performed in step 5.
This allowed the operator to quickly re-classify points from
one layer to another and recreate the TIN surface to see
the effects of edits.  Geo-referenced images were toggled
on or off to aid the operator in identifying problem areas.
The data was also examined with an automated profiling
tool to aid the operator in the reclassification.
7. The final bare earth was written to an LAS 1.0 format and
also converted to ASCII.
8. The point cloud data were delivered in LAS 1.0 format.
Organization: EarthData International, Inc.
Person: Becky Jordan
Position: Project Manager
Phone: 301-948-8550 x121
Fax: 301-963-2064
Email: bjordan@earthdata.com
Hours of service: Monday through Friday, 8:30am to 5:00pm
Address type: mailing and physical address
Address:
7320 Executive Way
City: Frederick
State or Province: MD
Postal code: 21704
Country: USA
Process date: 20061218
Data Source used
Lidar
Data Source produced
Lidar
Process Step 2
Process description:
EarthData utilizes a combination of proprietary and COTS
processes to generate intensity images from the lidar
data. Intensity images are generated from the full points
cloud (minus noise points) and the pixel width is typically
matched to the post spacing of the lidar data to achieve
the best resolution. The following steps are used to
1. Lidar point cloud is tiled to the deliverable tile layout.
2. All noise points, spikes, and wells are deleted out of the
tiles.
3. An EarthData proprietary piece of software, EEBN2TIF
is then used to process out the intensity values of the lidar.
At this point, the pixel size is selected based on best fit or
to match the client specification if noted in the SOW.
4. The software then generates TIF and TFW files for each
tile.
5. ArcView is used to review and QC the tiles before
delivery.
6. The lidar intensity data were delivered in TIF format.
Organization: EarthData International, Inc.
Person: Becky Jordan
Position: Project Manager
Phone: 301-948-8550 x121
Fax: 301-963-2064
Email: bjordan@earthdata.com
Hours of service: Monday through Friday, 8:30am to 5:00pm
Address type: mailing and physical address
Address:
7320 Executive Way
City: Frederick
State or Province: MD
Postal code: 21704
Country: USA
Process date: 20061218
Data Source used
Intensity
Data Source produced
Lidar Intensity Values
Process Step 3
Process description:
It should be noted that the breaklines developed for use in
the H&H modeling should not be confused with traditional
stereo-graphic or field survey derived breaklines.  The
elevation component of the 3D streamlines (breaklines) is
derived from the lowest adjacent bare earth lidar point
and adjusted to ensure that the streams flow downstream.
The best elevation that can be derived for the 3D
streamlines will be the water surface elevation on the date
that the lidar data was acquired.  The elevations in the 3D
streamlines will not represent the underwater elevations
for streams due to the fact that lidar data cannot collect
bathymetry information.
Watershed Concepts and EarthData have done
considerable research generating breaklines from lidar
data. Current H&H modeling practices rely heavily on
mass points and breaklines to create a realistic TIN
surface for hydrologic and hydraulic modeling. Lidar data
consists only of points, which are not suited to defining
sharp breaks on terrain. The problem is most pronounced
across stream channels, where lidar is not able to define
the stream banks clearly. Furthermore lidar does not
reflect off water; therefore, no reliable elevation points will
exist within the stream channel itself. The TIN surface
generated from lidar data alone is unsuitable for H&H
modeling.
Watershed Concepts engineers have studied the
sensitivity of the 100-year flood boundary to the definition
of stream channel geometry. The surface created with
both lidar points and breaklines improves channel
definitions for hydraulic cross section takeoffs and better
defines the stream invert. It is not necessary to create
breaklines on the top and bottom of stream banks; minor
modifications to the cross sections and stream inverts can
be made based on field survey data as necessary. In the
100-year flood, most of the flooded cross sectional area
occurs in the overbank; therefore, creating a more refined
channel definition from the lidar data is not cost effective.
The lidar TIN is used simply as the basis for the overbank
definition.
Our research indicates that breaklines are required at the
stream centerline for smaller streams with widths less than
50 feet.  For larger streams (widths greater than 50 feet,
breaklines are needed on the left and right water edge
lines.  Collection of photography and stereo compilation of
the breaklines is not cost-effective for this purpose.
Watershed Concepts and EarthData have developed
techniques to synthesize 3D breaklines using digital
orthophotos and lidar data. These breaklines can be
digitized in 2D from orthophotos, approximating the stream
bank in areas of significant tree overhang. A bounding
polygon, created from the edge of bank lines, is used to
remove all points within the channel. Automatic processes
assign elevations to the vertices of the centerline based
on surrounding lidar points. The lines are then smoothed
to ensure a continuous downhill flow. Edge-of-bank
vertices are adjusted vertically to match the stream
centerline vertices. A new TIN can then be created from
the remaining lidar points and newly created breaklines.
The new TIN clearly defines the stream channel.
For this project, breaklines were generated in the matter
described above for all streams draining greater than
approximately one square mile. 2D lines defining the
centerline and banks of those streams were manually
digitized into ESRI shape file format from 2005 imagery.
The streamlines were then processed against the bare
earth lidar as described above. The new 3D lines were
then viewed in profile to correct any anomalous vertices or
remove errant points from the lidar DTM, which cause
unrealistic "spikes" or "dips" in the breakline. The 3D
breaklines were delivered in ESRI shapefile format.
Person: Becky Jordan
Organization: EarthData International, Inc.
Position: Project Manager
Phone: 301-694-7762 x121
Fax: 301-963-2064
Email: bjordan@earthdata.com
Hours of service: Monday through Friday, 8:30am to 5:00pm
Address type: mailing and physical address
Address:
7320 Executive Way
City: Frederick
State or Province: MD
Postal code: 21704
Country: USA
Process date: 20070104
Data Source used
breaklines
Data Source produced
3D streamlines (breaklines)
+ Data Distribution Information
General
Description of the data known by the party from whom the data may be obtained, liability of party distributing data, and technical capabilities required to use the data.
Distribution liability:
None
Distribution Point of Contact
Contact information for the individual or organization distributing the data.
Organization: Mississippi Geographic Information, LLC
Person: Bill McDonald
Position: Project Manager
Phone: 601-355-9526
Fax: 601-352-3945
Email: Bill.McDonald@waggonereng.com
Address type: mailing and physical address
Address:
143-A LeFleurs Square
City: Jackson
State or Province: MS
Postal code: 39211
Country: USA
+ Metadata Reference
Metadata Date
Dates associated with creating, updating and reviewing the metadata.
Last updated: 20070115
Last metadata review date: 20070115
Metadata Point of Contact
Contact information for the individual or organization responsible for the metadata information.
Organization: EarthData International, Inc.
Person: Becky Jordan
Position: Project Manager
Phone: 301-948-8550 x121
Fax: 301-963-2064
Email: bjordan@earthdata.com
Hours of service: Monday through Friday, 8:30am to 5:00pm
Address type: mailing and physical address
Address:
7320 Executive Way
City: Frederick
State or Province: MD
Postal code: 21704
Country: USA
Metadata Standards
Description of the metadata standard used to document the data and reference to any additional extended profiles to the standard used by the metadata producer.
Standard name: FGDC Content Standards for Digital Geospatial Metadata
Standard version: FGDC-STD-001-1998
FGDC Plus Metadata Stylesheet
Stylesheet: FGDC Plus Stylesheet
File name: FGDC Plus.xsl
Version: 2.3
Description: This metadata is displayed using the FGDC Plus Stylesheet, which is an XSL template that can be used with ArcGIS software to display metadata. It displays metadata elements defined in the Content Standard for Digital Geospatial Metadata (CSDGM) - aka FGDC Standard, the ESRI Profile of CSDGM, the Biological Data Profile of CSDGM, and the Shoreline Data Profile of CSDGM. CSDGM is the US Federal Metadata standard. The Federal Geographic Data Committee originally adopted the CSDGM in 1994 and revised it in 1998. According to Executive Order 12096 all Federal agencies are ordered to use this standard to document geospatial data created as of January, 1995. The standard is often referred to as the FGDC Metadata Standard and has been implemented beyond the federal level with State and local governments adopting the metadata standard as well. The Biological Data Profile broadens the application of the CSDGM so that it is more easily applied to biological data that are not explicitly geographic (laboratory results, field notes, specimen collections, research reports) but can be associated with a geographic location. Includes taxonomical vocabulary. The Shoreline Data Profile addresses variability in the definition and mapping of shorelines by providing a standardized set of terms and data elements required to support metadata for shoreline and coastal data sets. The FGDC Plus Stylesheet includes the Dublin Core Metadata Element Set. It supports W3C DOM compatible browsers such as IE7, IE6, Netscape 7, and Mozilla Firefox. It is in the public domain and may be freely used, modified, and redistributed. It is provided "AS-IS" without warranty or technical support.
Instructions: On the top of the page, click on the title of the dataset to toggle opening and closing of all metadata content sections or click section links listed horizontally below the title to open individual sections. Click on a section name (e.g. Description) to open and close section content. Within a section, click on a item name (Status, Key Words, etc.) to open and close individual content items. By default, the Citation information within the Description section is always open for display.
Download: FGDC Plus Stylesheet is available from the ArcScripts downloads at www.esri.com.