The need and mission to collect enhanced elevation data at a national scale was addressed at the National Map User Conference by Larry Sugarbaker senior advisor to the National Geospatial Program. Elevation data is expensive to collect, and as a result the effort requires a collaborative approach. Since August of last year an effort has been underway to collect business requirements and benefits for a national enhanced elevation data program with outreach to all federal agencies and all 50 states.
The kinds of questions that are being asked are whether the federal government needs to manage these activities centrally or to take a cooperative approach as are done with other data sets. The cost justification are a critical element to move this activity forward, particularly in these constrained economic times.
Within the National Elevation Dataset, 80 percent of data is 30 years old and up to 88 years old. Twenty percent of the country has updated data at higher resolution, but does not always contain the derivative data necessary.
It has always been expensive to collect elevation data, with the traditional approach being the close analysis of stereo pair images by an operator. The introduction of lidar speeds collection, but is limited in that it can’t see through clouds. IFSAR is the other technology that can look through clouds, but the accuracy is lower, and it can’t support all the applications that are needed.
The assessment looks at four different levels of data quality, as well as where the data is needed, and how often it is needed. For example, the assessment of sea level rise in coastal areas requires a quality level of two in all coastal zones every three years. The National Geospatial-Intelligence Agency needs high-resolution elevation data in 133 cities every five years. The Federal Emergency Management Agency needs detailed elevation data to support the flood insurance program. All told, there are 100 mission-critical requirements across all federal agencies, and the work runs into the multi-billion dollar range on a yearly basis.
At present the project is working at the edges to understand the requirements, and to meet the needs of a broad customer base. Much of the work is being done under contract, with Dewberry as the prime contractor to help assess the cost benefits and the approach. You can see more details on the goals, approach and benefits of an integrated and national view of elevation at the National Digital Elevation Program website.