325 Broadway
Boulder, CO 80303
Phone: 303-497-7590

Topic: Adventures with Point Data

Email: cng@ngdc.noaa.gov

Web: http://www.ngdc.noaa.gov/seg/

1. Prototype-use existing SDTS translators within NGS packages.

2. Develop encoder for NGS point (control) data.

3. Extend encoder to make more generic.

While initially using the TVP, NOAA found it allowed transfer of point data but a few problems were encountered. The Associated polygon was one, uppercase filenames and the 32 bit binary integers were nine figures. NOAA needed high precision 11 significant integers.

ESRI's ArcInfo encoder was used extensively. SDTSEXPORT seemed to work well for point data as did the point attribute module. The decoder, however truncated the integers to seven and point attributes were confused. Carol stated that ESRI was aware of the problems and were working to rectify them.

NOAA is now working on an encoder for NGS data and chose to use and the USGS FIPS123 libraries. They are still in the process of populating modules with data. Carol noted that as with any relational database system, understanding what goes where is much more work than the encoding. Some modules are very detailed and cautioned those wishing to encode SDTS data to allow ample time for this aspect of the project.

Sharing data on the Web is expected in approximately three months. Geodetic data will be extracted by region, position, project number and possibly county-wide. This will be done on the fly.

NGS approached the USGS and EDC about developing a draft document for a Point Profile, which is now SDTS Part 6. Endorsement of the Standards Working Group and Coordination Group at FGDC has been achieved and the formal stamp of approval is expected later this year. Seeking ANSI approval will follow. This profile allows double precision coordinates with the option for single precision as well. The Federal Geodetic Control Sub-committee sponsored this effort and will maintain the Profile.

NGS developed Data Descriptor Language for file input that will read data into a wide variety of formats. They will put this together with SDTS output to make one translator (one encoder) for point datasets in general. In closing, Carol emphasized the need for decoders from the SDTS community.