9. DIGEST and VPF Profiles

Including:

(1) DIGEST Vector Profile (DVP) to SDTS,

for Vector Product Format (VPF) or DIGEST A.

(2) Relational Vector Profile (RVP) to SDTS,

for Vector Relational Format (VRF) or DIGEST C.

(3) possible profiles for other vector and raster varieties of DIGEST.

Intended Use --

The proposed DIGEST/VPF profiles to SDTS are designed to allow transfer of digital geospatial data that conforms to both SDTS and DIGEST/VPF. In general, a VPF profile to SDTS will serve as a "bridge" between SDTS and VPF in an effort to harmonize the two standards. This profile activity is a way to clarify and reconcile information in both standards so that they are more similar and have a wider area of overlap. Past and current DIGEST/VPF profiles to SDTS will also be valuable in any future efforts by ISO to harmonize several major geospatial data exchange standards.

The Digital Geographic Exchange Standard (DIGEST) (DGIWG, 1994) is the primary spatial data exchange standard for the military communities of many nations, including NATO nations. DIGEST is also now the exchange standard of the civilian transportation community in Canada. The DIGEST standard supports data models for

1. complete topology vector (type 3 topology),

2. planar graph vector (type 2 topology)

3. chain-node vector (type 1 topology)

4. spaghetti vector (type 0 topology)

5. raster (graphic, not image) data

6. matrix (elevation & thematic, not image) data

VPF and VRF are the NIMA feature-based, complete topology vector implementations of DIGEST A and DIGEST C (respectively) for direct use as well as data transfer. VPF or VRF is the distribution format for Digital Chart of the World (DCW), Digital Nautical Chart (DNC), and other NIMA products.

(1) The DIGEST Vector Profile (DVP) to SDTS was successfully defined and documented in 1992 by IDON under contract to DMA. DIGEST content is specified by the FACC feature catalog. The DVP requires FACC use. Implementation of the DVP has not been a high priority because of limited use of feature-oriented DIGEST A in favor of relational (and conceptually feature-based) DIGEST C.

(2) The Relational Vector Profile (RVP) to SDTS was developed in 1996 by SAIC under contract to NIMA. This profile may also be considered a VPF Relational Profile to SDTS and a DIGEST C Profile to SDTS. RVP suggests VPF encapsulation rather than ISO 8211 at the physical implementation level

(3) SDTS profiles for other vector and raster varieties of DIGEST have been suggested, but not yet planned or developed.

Primary Sponsors, Interested Groups, and Contacts --

(1) DMA (now NIMA) through the IDON Corporation, with input from USGS, was the primary sponsor for the DVP.

(2) NIMA, through SAIC, with input from USGS and LaserScan, was the primary sponsor for the RVP.

Documents --

(1) The draft DVP document is dated 10-30-92.

(2) The draft RVP document is dated 9-30-96.

"A Look at Two Geographic Data Exchange Formats: DIGEST and SDTS" by Anthony Sani and Vincent Robinson, 1992, University of Toronto.

"Harmonization of SDTS and DIGEST, Final Report" by IDON Corporation (Ottawa, CANADA) for DMA, 11/16/92.

MIL-STD-600006 (VPF).

DIGEST 2 was expected in late 1996.

Future Plans --

The 1996 investigation by SAIC for NIMA indicates that the RVP can be implemented. NIMA, USGS, FGDC, and ANSI are interested in making this connection between SDTS and VPF.

This activity can benefit the international effort to harmonize various spatial data exchange standards (DIGEST, SDTS, GDF, S-57, NTF, and others) as they move toward ISO approval.

The 1992 DVP document from IDON contained recommendations for the other DIGEST profiles to SDTS including

DIGEST Vector Profile Chain-Node

DIGEST Vector Profile Spaghetti

DIGEST Matrix Profile

DIGEST Raster Profile.

The DIGEST matrix standard for grid-based elevation and thematic data, and the DIGEST raster standard for scanned map graphics may be examined for possible harmonization with the new SDTS Raster Profile with BIIF Extensions which is the result of a successful effort to reconcile the civilian SDTS raster standard with imagery and raster standards (NITF and BIIF) from the military and intelligence communities.