Creating an On Target Geospatial Foundation for the Navajo Housing Authority

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Claribel Caldwell
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1 Creating an On Target Geospatial Foundation for the Navajo Housing Authority 2012 Geospatial Excellence Awards

2 MAPPS 2012 Geospatial Products and Services Excellence Awards 2012 Awards Entry Form Please include a copy of this document with the project/product submission Entry Information Submission Number: Name of Firm: AeroMetric Address: 4020 Technology Parkway Sheboygan, Wisconsin USA Primary Contact: Antonio Montoya Primary Contact Phone Number: Primary Contact amontoya@aerometric.com Project Manager: Miles Strain Project Manager mstrain@aerometric.com About the Project Project Name: Creating an On Target Geospatial Foundation for the Navajo Housing Authority Category: B. Photogrammetry/Elevation Data Generation Geographic Location of Project: Navajo Nation, USA Scheduled Date of Completion: 11/30/2011 Actual Date of Completion: 11/10/2011 Affirmed: I agree that this project follows the completion date criteria Budgeted Fee: $1,776,105 Actual Fee: $1,776,105 Yes: I accept the competition rules. Yes: I am aware that a client/owner letter must be submitted as part of the bound submission for Categories A-F, due August 31, The letter must include the permission to publicize project s details with respect to its complexity, innovative application of technology or techniques, and value to the geospatial profession and the public.

3 Creating an On Target Geospatial Foundation for the Navajo Housing Authority CREATING AN ON TARGET GEOSPATIAL FOUNDATION FOR THE NAVAJO HOUSING AUTHORITY Meeting the challenges of developing a geospatial land base for the Navajo Housing Authority across a rugged and unforgiving, 19.2M-acre desert area. Overview The Navajo Nation is the largest semi-autonomous Native American-governed land area within the United States. Occupying large portions of northeastern Arizona, southeastern Utah, and northwestern New Mexico it is about the size of West Virginia. This wild and dramatic expanse has served as backdrop to many Western films set in the imposing terrain of Monument Valley. The Navajo Nation is also home to more than a dozen national monuments, tribal parks and historical sites. Among the daunting tasks faced by the Nation has been the need to provide adequate services and housing to the population of over 300,000 Navajos scattered across this vast area. Working to address this need in 2009, the Navajo Housing Authority 1 began development of a land information system, which would enable them to manage land survey records, home site leases, and environmental data. The system would ultimately serve a host of other applications as well. AeroMetric was selected to establish a precise ground control network, develop a custom, project-wide horizontal datum, obtain digital imagery and create a digital elevation model (DEM) and digital orthoimagery at 0.5 meter ground sample distance for the base layers of the system. Delivery items included ground control data, 3229 orthophoto 5km x 5km tiles, ESRI raster and ASCII DEM grids and vector data plus associated metadata files. Although contours were not a delivery item the specifications mandated that DEM s would be suitable to subsequently contribute to the generation of 10-foot contours. The imagery was also immediately used for flood plain delineation in 5 specific areas and will be used in additional areas for this application in the future. Complexity AeroMetric s initial challenge was to develop a ground control survey network and preserve it for future reference by establishing 73 semi-permanent monuments in the vast area. The complexity of this task is compounded as the Navajo Nation spans 4 states and 5 state plane coordinate systems across 2 UTM zones (imagery tiles extend beyond the Nations boundaries into SW Colorado). The second major challenge was to coordinate the image acquisition during the very short weather window before the rainy season and ensure consistent image quality among multiple aircraft and subconsultants. 1 The Navajo Housing Authority (NHA) is the housing entity authorized by the Navajo Nation to administer a grant from the U.S. Department of Housing and Urban Development. The U.S. Army Corps of Engineers, St. Louis District provided technical and administrative support to the Authority and contracted with AeroMetric via their multi-year Indefinite Delivery Contract to provide professional geospatial services for the project. MAPPS Geospatial Products and Services Excellence Awards

4 Creating an On Target Geospatial Foundation for the Navajo Housing Authority The next challenge was to compile a detailed digital elevation model (DEM). The ragged cliffs of the numerous buttes and canyons required determining detailed breaklines across the entire project area, which would have been impractical to accomplish manually. The final challenge was to produce consistent orthoimagery. The extreme ranges of color and contrast make it notoriously difficult to create anomaly-free, aesthetically acceptable orthophotos in desert terrain. Innovative Techniques AeroMetric approached these challenges by using an evidence-based approach in which the initial project methodology was continually reviewed as issues were identified to eventually perfect a custom workflow based on best-of-class tools and techniques. As ground surveys were being completed a custom map projection system was conceived to provide a single datum and coordinate system for the entire project area. This involved identifying the best projection system for the area, while determining the specific parameters to minimize measuring errors and ensure the accurate coordinate conversion from the newly developed system to geographic and other map projection systems. The result is the Navajo Housing Authority Stereographic Double Projection System. Subconsultant Towill, Inc. developed the ground survey and the custom NHA projection system as a subconsultant to AeroMetric. For aerial image acquisition AeroMetric chose Z/I DMC 4-band digital aerial cameras equipped with gyro-stabilized mounts and integrated GPS/IMU s. The project area was divided between subconsultants Surdex Corp. and Aerial Surveys International, LLC. Acquisition was coordinated so that flight dates would be as close as possible by strip. 8,437 images with a half-meter ground sample distance and simultaneous airborne GPS position data were obtained. Raw image and associated metadata were quality-checked and post-processed by AeroMetric at the end of each mission. Aero-Triangulation was conducted in two different AeroMetric locations, which allowed comparative cross-checking and verification. Digital elevation models (DEMs) were derived from the imagery to meet the NHA specifications, however, the challenge in this task proved to be modeling the abrupt elevation changes in the rugged terrain. After confirming that manual breakline collection for the entire area would be unfeasible within the schedule and budget allocated to the project, the AeroMetric team implemented an innovative approach by automatically generating a 2-meter post-spacing DEM, sixteen times more dense than required by the final deliverables. This higher resolution DEM captured the vast majority of the terrain changes, minimizing the need for manual breakline collection while increasing the confidence in the final DEM results. AeroMetric then used a custom approach to thin the DEM to the 8-meter post-spacing required by the client without losing the more detailed breakline information. Next, AeroMetric employed stereo-editing software to refine the DEM s further by interactive visual inspection and manual addition of the required breaklines. The last challenge to create a project-wide elevation model was to identify and fix any artifacts created between DEM tiles. Finally, AeroMetric utilized GIS tools to review the assembled DEM s across the entire project area. This innovative procedure permitted MAPPS Geospatial Products and Services Excellence Awards

Creating an On Target Geospatial Foundation for the Navajo Housing Authority our photogrammetrists to catch and smooth stepping and gaps between tiles, and allowed for a superior final project

5 Creating an On Target Geospatial Foundation for the Navajo Housing Authority our photogrammetrists to catch and smooth stepping and gaps between tiles, and allowed for a superior final project deliverable that could be used as another base layer of the NHA geospatial infrastructure. The ortho-rectification process needed to meet the significant challenge of accurately modeling the rugged terrain as well as color balancing across the entire area. The AeroMetric approach included an initial color balancing of the un-rectified aerial imagery grouping it by strip and date so that the images processed had similar time and atmospheric conditions. This pre-balancing facilitated all subsequent steps as AeroMetric staff established seamlines, which would minimize terrain distortions, obscured areas, and other artifacts created by the challenging desert landscape. Figure1: AeroMetric designed a custom processing workflow for the Navajo Housing Authority to address the challenges of multiple state plane projection systems and UTM zones, extremely rugged terrain and unforgiving desert landscape. Future Value to the Geospatial Profession and the Public Modern land information management systems demand not just a map, but a comprehensive land-base including geodetic, imagery and elevation components. The Navajo Housing Authority project is emblematic of the current challenges faced by the photogrammetric profession as local and regional governments and even large land owners recognize the need to develop accurate and information-rich geospatial data infrastructures for a variety of applications. Projects of this magnitude once required massive budgets and years to complete. Today thanks to ever evolving digital technologies, professional knowhow and ingenuity, these projects are not only more feasible but can provide significant value sooner to government agencies, private enterprise and the public. AeroMetric s contribution is not limited to developing its own custom workflows and processes but also collaborating with technology vendors, peers and clients to deliver better and more complete geospatial services faster and more efficiently. Finally, this project showcases the effectiveness of the private enterprise model to efficiently allocate resources to tackle very large and complex projects. AeroMetric MAPPS Geospatial Products and Services Excellence Awards

6 Creating an On Target Geospatial Foundation for the Navajo Housing Authority assembled a powerful team including Towill, Surdex and Aerial Surveys International, which brought together the necessary resources to successfully complete this project within the allocated budget and schedule. AeroMetric has made it a core competency to assemble strong multi-firm teams and to coordinate team efforts so that all work together in a seamless collaborative environment to provide maximum value to the client. Client Satisfaction AeroMetric completed the project on schedule and on budget, providing a cost-effective and information-rich land base that can be used for a wide variety of geospatial applications. The Navajo Housing Authority Stereographic Double Projection System greatly simplifies the ability of NHA and other constituents to relate existing and future ground survey data and create a true multi-purpose land information system for the Navajo Nation. In the words of Ted Stanton, administrator of the Navajo Housing Authority project for the Army Corps of Engineers, The services AeroMetric provided for the Navajo Housing Authority project reflect well on the value that AeroMetric and the geospatial profession bring to the development and economic growth of our nation. The NHS specific map projection, detailed digital elevation data and four-band orthoimagery provide a comprehensive digital land base for the Authority s new land information system. AeroMetric s Minneapolis site manager, Miles Strain, summed up the company s view of the Navajo Housing Authority project, We are proud to have been selected to serve the needs of the Authority by providing geospatial data and imagery of the Navajo Nation area. We are privileged to build our professional service-provider/client relationship to help address the myriad applications across the Nation by delivering the Authority s new geospatial dataset. And finally, we are humbled to be part of this key element in the Navajo Housing Authority s effort to improve the lives of the Navajo people. A perhaps more telling indication of client satisfaction is AeroMetric s long term professional relationship with the Army Corps of Engineers and the Navajo Housing Authority which continues to this day through subsequent task orders in MAPPS Geospatial Products and Services Excellence Awards

MAPPS 2012 Geospatial Products and Services Excellence Awards Awards Entry Form

MAPPS 2012 Geospatial Products and Services Excellence Awards 2012 Awards Entry Form Please include a copy of this document with the project/product submission Entry Information Submission Number: 1741558