This is the first release of the FAQ (Frequently Asked Questions) for the Spatial Archive and Interchange Format (SAIF).
This FAQ will be crossposted periodically to the following newsgroups:
If you have any suggestions for corrections, changes, expansion or further clarification of this FAQ, please send them to the SAIF FAQ author and maintainer, Dale Lutz, care of "infosafe@safe.com".
Spatial Archive and Interchange Format (SAIF, pronounced safe) is a Canadian geomatics standard for the exchange of geographic data. The underlying model itself is devoid of geographic meaning; rather it deals with fundamental concepts from mathematics and computer science. SAIF uses an object oriented data model, and consists of definitions of the underlying building blocks, including tuples, sets, lists, enumerations, and primitives. It also includes the rules for defining higher level constructs, and the SAIF standard defines a base set of approximately 300 classes. These include such things as Points, Spatial Reference Systems, Map Projections, Arcs, and Polygons.
By design, SAIF is intended to be extended by users through the development of their own schemas. SAIF has an object oriented data definition language, Class Syntax Notation (CSN), which is used to define new types. In addition to being useful as the means of extending SAIF, CSN is also the language employed to describe all of the types included in the SAIF base schema.
Instances of objects in SAIF are expressed using Object Syntax Notation (OSN), a simple character based notation.
There is also a binary exchange file format defined for SAIF data based on the 'zip' compression format called SAIF/ZIP. A SAIF toolkit is being produced which will make it easy to read and write SAIF data in this format (see Q4).
A company has formed to provide tools and training for the SAIF data standard. Safe Software may be contacted by email at infosafe@safe.com or by phone at either (604) 241-4424 or (604) 583-2016.
In 1991 SAIF was accepted as a draft standard for the exchange of geographic data by the Canadian General Standards Board, Committee on Geomatics. Since that time several upgrades have been made, culminating in the current specification. SAIF has been approved (1993) through the CGSB process as a national standard in Canada. The province of British Columbia has been using SAIF for more than two years.
The present document, Release 3.1, contains a number of significant changes made in response to two related efforts. The first involves the development of the ISO SQL Multimedia Spatial standard. A new release of SQL, SQL3, is being developed. SQL/MM will be a companion standard. The SQL/MM Spatial is a component of SQL/MM intended to address the management of spatial and spatiotemporal data in the context of database management systems.
The second effort concerns the development of the Open Geodata Interoperability Specification (OGIS) under the auspices of the Open GIS Foundation (OGF). The OGF has been designated (1994) by the U.S. Federal Geographic Data Committee as the lead organization responsible for defining an interoperability specification suitable for geoprocessing activities.
Harmonization of SAIF, SQL/MM Spatial and OGIS is leading to a common understanding of geomatics data. Integration with DIGEST and SDTS is also being addressed.
SAIF is a product of the Geomatics Unit, Surveys and Resource Mapping Branch (SRMB) of the British Columbia Ministry of Environment, Lands and Parks. SRMB is involved in geographic data management, geographic analysis, and image applications. The following individuals have been involved with the SAIF initiative:
Joe Carr ------ SAIF Toolkit Internet: jcarr@venus.gov.bc.ca Tel: (604) 387-1353 Peter Friesen - modelling and applications Internet: pfriesen@venus.gov.bc.ca Tel: (604) 387-9347 Henry Kucera -- databases and Canadian ISO SQL/MM Spatial contributions Internet: hkucera@venus.gov.bc.ca Tel: (604) 356-2388 Mark Sondheim - SAIF formal definition; director of the SAIF initiative Internet: msondheim@galaxy.gov.bc.ca Tel: (604) 387-9352
SRMB's fax number is (604) 356-7831.
SRMB would like to extend special thanks to those in the ISO SQL, OGIS, and Sequoia communities who have contributed both directly and indirectly to SAIF.
SRMB staff have also provided material for this FAQ.
At the moment, there are no tools available to manipulate SAIF data. However, by the fourth quarter of '94, the SAIF Toolkit will be available. This toolkit is being developed for the Surveys and Resource Mapping Branch of the BC Ministry of Environment, Lands and Parks by Safe Software Inc. of Richmond, BC. The toolkit will contain a C library for reading and writing data in SAIF format, which will simplify the creation of SAIF translators. As well, the toolkit will contain tools to allow inspection and testing of SAIF Schemas.
The Toolkit is designed to work with SAIF datasets. Four points are noteworthy:
Although portability is the goal, the toolkit will initially target the Windows 3.1 and Solaris platforms. It is being written in C++ and will be useable by both C and C++ developers in both Unix and Microsoft Windows environments.
Safe Software will also be producing a suite of SAIFTools which will supplement those provided by the toolkit.
If you are interested in more information about the SAIF Toolkit or would like to participate in its testing or design reviews, please contact Joe Carr.
http://www.wimsey.com/~infosafe/saif/saifHome.html
This home page will be continually updated to point to all known SAIF information available on the net.
SAIF Info,
Surveys and Resource Mapping Branch,
B.C. Ministry of Environment, Lands and Parks,
Fourth Floor, 1802 Douglas Street,
Victoria, BC CANADA V8V 1X4
Tel: (604) 387-1353
Fax: (604) 356-7831
MAPSBC
Surveys and Resource Mapping Branch
B.C. Ministry of Environment, Lands and Parks
Third Floor, 1802 Douglas Street
Victoria, BC CANADA V8V 1X4
Tel: (604) 387-1441
Fax: (604) 387-3022
Yes, a fully hypertexted version of the SAIF 3.1 specification document is available at:
http://www.wimsey.com/~infosafe/saif/saif31spec.html
The SAIF specification is available from the following two FTP sites:
site: s2k-ftp.cs.berkeley.edu
directory: pub/sequoia/schema/STANDARDS/SAIF
site: moon.cecer.army.mil
directory: ogis/related/SAIF3.1
You should get the SAIF 3.1 specification document (either hardcopy softcopy, or by browsing the Web).
If you are looking for a very high level understanding of SAIF, read the Foreword and Section 1.1 only. This amounts to two pages.
If you want a greater degree of familiarity, say something that can be digested in an hour or so, the following sections are suggested: 1.1, 1.2, 1.3, 2.1, 2.4, 2.5, 2.6, and 4.7. These constitute about 29 pages.
The WWW version of the document has a quick tour that will guide you to these parts.
To come up to speed with the SAIF base set of classes, we recommend you browse them with a hypertext tool rather than by reading the document. If you have WWW access, you can do that (see Q6).
For those who do not have Web access, Safe Software is considering producing a stand-alone Windows 3.1 hypertext version of the specification and distributing it for a small handling charge. Send email to "infosafe@safe.com" if you would be interested.