Kim Ollivier Ollivier & Company New Zealand Dear Kim, In regard to your direct message to me of last week and later posting to the GIS-L on 12 Jun, the early records of survey work in Formosa date back to a Japanese Hydrographic Department survey of the west coast in 1897. Between 1900 and 1904 the Government General of Formosa under the supervision of the Japanese Government established approximately 2,000 stations. Japanese Imperial Land Survey initiated their work on a first-order net in Formosa in 1909. The system for this and succeeding lower-order triangulation is the Koshizan 1906 Datum where the origin is at station Koshizan where Latitude = 23* 58' 32.3400 North, and Longitude = 120* 58' 25.9750" East of Greenwich,and the initial azimuth is to south end of Horisha base where az = 243* 47' 21.611". Of course, the ellipsoid of reference is the Bessel 1841; the same as the Tokyo Datums of the 19th and 20th centuries. The Grid system is/was known as the Formosa Grid (since merely renamed the Taiwan Grid), and is the Gauss-Schreiber Transverse Mercator. Note that this is the double projection that first is transformed to the equivalent sphere before ellipsoidal correction terms are added so the projection is not perfectly conformal as is the Gauss-Kruger used for UTM. The Formosa/Taiwan TM Latitude of Origin is = 23* 40' 00.000" North, Central Meridian is Longitude = 120* 58' 25.9750" East of Greenwich. (No False Easting or False Northing were used, per the Japanese way of doing things). Note that the Japanese STILL do not use False Easting or False Northing for their Civil Grid of Japan in a kazillion different zones!! They really do use negative numbers for both X and for Y coordinates when they fall in the appropriate quadrants. They may have assigned False Eastings for their own convenience for civilian applications in Taiwan since WWII. If your value of 450 km is the range of eastings for your maps in-hand, it's likely at the Central Meridian listed above. The military of the Republic of Taiwan uses the Hu-Tzu-Shan Datum of 1950 and it is referenced to the International ellipsoid. For military applications, they use the UTM. Considering who is snarling at them on a regular basis, I do not expect to get much more info on geodetic reference systems for Taiwan in the near future. If you scrounge anything, I'd appreciate a copy. Don't get hanged for espionage! Sorry it took me a while to look this up for you; I was at a Pistol Match with my youngest son (18yrs) and my youngest daughter (12yrs). Only family or pistols take precedence over Grids and Datums. In this case it was both! Consider joining the American Society for Photogrammetry and Remote Sensing. I strongly recommend it. Clifford J. Mugnier ([EMAIL PROTECTED]) Surveying, Geodesy, and Photogrammetry LOUISIANA STATE UNIVERSITY 12408 CEBA Building Baton Rouge, Louisiana 70803 Voice and Facsimilie: (225) 388 - 8536 ---------------------------------------------------------------------- To unsubscribe from this list, send e-mail to [EMAIL PROTECTED] and put "unsubscribe MAPINFO-L" in the message body, or contact [EMAIL PROTECTED]
