Enterprise Case Study -- Virtual Alabama and Google Earth for by tut53443

VIEWS: 84 PAGES: 4

									Alabama Statewide Digital Ortho-photography and LIDAR Mapping Project

Introduction
Recent years have seen the purchase of an increasing number of LIDAR surveys and
digital ortho-photography by municipalities and public agencies in Alabama. Uses for
the data include Economic Development, Parcel Mapping, Emergency Planning, Flood
Map Modernization, Geologic Mapping, ground-water modeling and management,
Highway Planning, and Urban and Suburban Infrastructure Engineering. A single
statewide program can be managed and implemented for far less money than state
and local governments spend when they issue independent contracts. This program
will offer outstanding value to local governments through price breaks achieved
through volume (area) discounts. This main objective of the program will be the
creation and establishment of a consistent, accurate, foundational base map upon
which local government and many regional, state and federal geospatial data
applications could be built, working towards producing an efficient statewide spatial
data infrastructure. Aerial imagery is the foundation for most public and private GIS
(Geographic Information Systems) operations, yet it is being developed by many
different entities across Alabama in an uncoordinated fashion. Some areas are
essentially “left behind” due to lack of coordination or funding. There are holes in the
coverage, varying qualities of product and the duplication of effort leads to higher
costs; varying quality, accuracy and age along with restrictions on its access and
use. This program will ensure the widest utility of digital ortho-photography and
elevation data for the user and producer communities through enhanced data
sharing and the reduction of redundant data production.

The goals of this project are;

   -   Acquire 1”=200’ color and color infrared digital ortho-photography statewide

   -   Acquire two foot contour data statewide collected and processed to meet
       specifications called for in FEMA’s Guidelines and Specifications for Flood
       Hazard Mapping Partners.

   -   Establish a Statewide Mapping Program for the perpetual maintenance of this
       data set.

This plan has been developed based on the findings of the AlabamaView Consortium
which are described in the Statewide Digital Orthophoto Fly Plan for the State of
Alabama report. This document outlines the projected benefits and cost savings of
acquiring data on a statewide basis as well as proposes the methods by which to
develop such a program.

Specifications
The first task for this project will be to develop a common specification for public
agency digital ortho-photography and LIDAR surveys acquisition. A common
specification will ease the writing of acquisition contracts, facilitate the sharing of
data across agencies, increase the overall usability of the data, and minimize cost to
the public. While these type acquisitions can be designed for different resolutions,
accuracies, and costs to meet particular needs, the likely benefits from acquisition of
data suitable for multiple uses far outweigh any short-term savings from acquisitions
of less accurate or lower resolution data.
Geodetic Foundations
The key component to any successful remote sensed data acquisition is the
supporting geodetic network used to control horizontal and vertical positioning. In
1994, work was completed on the first order horizontal control network established
on a six mile grid throughout the state. The update of this system began through
the Alabama Height Modernization Project by establishing a network of high order
horizontal marks with high order elevations in 2004. The Alabama Continuously
Operating Reference Station Network currently under construction will complete the
required geodetic framework to support all phases of the project. This Geodetic
Foundation will ensure that all data is collected to the accuracy required and is
appropriately tied to the National Spatial Reference System (NSRS) while providing
the cost savings over conventionally controlled mapping projects.

Digital Ortho-Photography
Digital Ortho-Imagery provides the visual content of an aerial photograph while
being as accurate as a map for measurements. These qualities allow users to easily:
    - Measure Distance
    - Calculate Areas
    - Determine Shapes of Features
    - Calculate Directions
    - Determine Accurate Coordinates (Locations)
    - Determine Land Cover & Use
    - Perform Change Detection

Ortho-photography is displayed in E-911 response centers to dispatch first
responders to exact locations and for tracking incoming calls from mobile phones.
Police in squad cars and rescue workers in fire trucks analyze ortho-photography
before responding to emergencies. Digital images are used to collect a wide variety
of information, including transportation routes, wetlands, streams, shorelines,
building outlines, timber stands, land use patterns, farm fields, and crop types.
Local governments rely on ortho-photography to map land property boundaries and
to manage their streets and other infrastructure assets. Ortho-photography serves
as a seamless base map layer to which many other layers are registered. It provides
visual information for the following partial list of applications.

   -   Homeland Security, Homeland Defense & Emergency Management
   -   Economic Development
   -   Public Safety Planning, Response & Mitigation
   -   Tax Parcel Mapping
   -   Transportation Management, Operations & Planning
   -   Utilities Management, Operations & Planning
   -   Land Planning and Zoning
   -   Drainage Planning & Management
   -   Code & Permit Enforcement
   -   Agriculture
   -   Insurance
   -   Surveying & Mapping
   -   Environmental Management, Planning & Regulation
   -   Education
   -   Natural Resource Inventories and Assessments
LIDAR (Light Detection and Ranging)
LIDAR is a technology that employs an airborne scanning laser rangefinder to
produce detailed and accurate topographic surveys. LIDAR can be used to accurately
measure the topography of the ground, even where overlying vegetation is quite
dense. As the technology has matured, and the analysis and utilization of the entire
LIDAR signal has improved and increased, utilizations of the entire dataset and not
simply bare earth derivatives have developed dramatically. LIDAR data are being
utilized extensively in the forestry and ecology realms, and the new uses are being
demonstrated in feature extraction of man-made structures in urban settings for
building delineations and emergency response and homeland security purposes.

The opportunity to begin collecting LIDAR data is quite advantageous to the
Program. In evaluating various options for LIDAR collection and processing, it
became apparent that there would be significant synergies in combining the ortho-
photography and LIDAR efforts. Evaluation of labor costs for each individual phase of
the work confirmed substantial cost and workflow savings could be realized by
combining efforts. The Digital Elevation Model (DEM) compiled from the LIDAR will
replace the labor required to generate the DEM to support the imagery. In addition,
utilizing the CORS network for Air Borne GPS for each phase of the project will
dramatically reduce the amount of ground control required to support the project.


Summary of Project Specifications

              Orthophoto              Terrestrial LiDAR (2 ft surface)
              (1”=200’)
 Horizontal   7.6-foot horizontal     3.8-foot horizontal accuracy (2.2 foot RMSE)
 Accuracy     accuracy (4.4 foot
              RMSE)

 Vertical     Based upon digital      0.6-foot fundamental vertical accuracy
 Accuracy     elevation model

 Projection   Alabama State Plane     Alabama State Plane US Feet Survey
              US Survey Feet          NAD83(NSRS2007)
              NAD83 (NSRS2007)
              Adjustment

 Datum        NAD 83 (NSRS2007)       NAVD 88 (based upon latest Geoid)


 Post-        1 foot                  4 foot
 spacing /
 pixel size
 Format       TIFF uncompressed       LAS 1.1
              Natural Color and
              Color Infrared
 Flight       Leaf-off                Leaf-off
 Season
 Breaklines                           Hydrologically correct breaklines


 Metadata                                        FGDC
 Contours                                    Two foot
 LAS 1.1                               Class1, Class 2, Class 7, Class 9, and Class
 (ASPRS)                               12




Local County and City Participation
County and city government may have certain needs for mapping products above
and beyond the scope described in this document. These needs may include some or
all of the following:

   -   0.5’ resolution imagery
   -   Building footprints
   -   Road Centerlines
   -   Pavement edges
   -   Impervious features
   -   Visible Utilities
   -   Any other photo-identifiable feature which can be collected in a vector format.

County and city governments will be given the option to “buy-up” to these options
with the pricing based on the level of effort above and beyond the initial acquisition
by the state. Additional feature capture or resolution enhancement on behalf of
governmental entities for deliverables other than those identified in the Contract will
require a separate agreement between the successful Contractor and participating
counties, municipalities, or State agencies.

Long Term Update and Maintenance
As with any remote sensed data, the original acquisition data will have a “shelf-life”
or a period of usefulness. As development and growth continue in Alabama, updates
for these data sets at regular intervals will be an important component of the
project. This project will bring together a group of partners and stakeholders with a
shared interest in developing and maintaining a program to support the perpetual
maintenance of the data sets.

Cost of the Proposal
The State estimates that a statewide program will cost approximately $15 million for
the initial acquisition of imagery and LIDAR data. The maintenance costs are
estimated at approximately $1.3 million per year based on industry pricing.

Conclusion
The State of Alabama has the unique opportunity to leverage existing partnerships,
programs, and funding for the initial acquisition of a reliable, up to date, ortho-
photography and LIDAR base map. The justification for this project is simple: Due
to the economy of scale, the State of Alabama will spend less money acquiring this
comprehensive data set, than the sum of all of the individual projects over the same
time period which will still not produce an overall, complete map of the state. The
added long term benefits derived from the creation of a state map, improved data
quality, standards and practices for data sharing, and community building will greatly
enhance the state’s ability to manage its resources and provide the citizens of
Alabama efficient government services.

								
To top