I am planning part of the Tainan's water sewers recently, and I discovery a problem about the coordinate system. I opened the water sewers drawing of AutoCAD format, and then I selected the coordinates（N, E）of some target nodes for the corporate surveying drawing. Because of the unreasonable positions, I thought the selected coordinates were incorrect. After I checked the coordinate systems, I knew that the water sewers drawing used TM2TWD67 and the corporate surveying drawing used TM2TWD97.
Actually, two coordinate systems exist simultaneously in Taiwan, and the users have to know which one is the present coordinate system they use. Hence, if an engineer gets a drawing, he or she shall firstly ask the opposite side what the coordinate system is. TM2TWD97 is base on the newest geodesic survey, so that it should be more accurate than TM2TWD67. Therefore, I suggest that the engineers should use TM2TWD97 but TM2TWD67. If the engineers do not use the same coordinate system, the surveying marking of construction shall be incorrect.
The unified coordinate system should let the engineers easier understand each other, and therefore the government shall have their attention on this matter firstly. If anyone would like to transfer the coordinates, he or she can browse the EPA website. The web service of the EPA website is very powerful, and it can transfer TM2TWD97, TM2TWD67 and WGS84 coordinate systems each other. Besides, I provide some data of fundamental knowledge, so that anyone can understand what's the different between TM2TWD97 and TM2TWD67.
References
Actually, two coordinate systems exist simultaneously in Taiwan, and the users have to know which one is the present coordinate system they use. Hence, if an engineer gets a drawing, he or she shall firstly ask the opposite side what the coordinate system is. TM2TWD97 is base on the newest geodesic survey, so that it should be more accurate than TM2TWD67. Therefore, I suggest that the engineers should use TM2TWD97 but TM2TWD67. If the engineers do not use the same coordinate system, the surveying marking of construction shall be incorrect.
The unified coordinate system should let the engineers easier understand each other, and therefore the government shall have their attention on this matter firstly. If anyone would like to transfer the coordinates, he or she can browse the EPA website. The web service of the EPA website is very powerful, and it can transfer TM2TWD97, TM2TWD67 and WGS84 coordinate systems each other. Besides, I provide some data of fundamental knowledge, so that anyone can understand what's the different between TM2TWD97 and TM2TWD67.
References
- Environmental Protection Administration, Environmental GIS, Executive Yuan, R.O.C., http://gis.epa.gov.tw/TransCoordFrame.aspx
- 周學政, 地理座標, 國立臺灣師範大學地理學系, http://www.geo.ntnu.edu.tw/faculty/hchou/class/gis/NOTES/projection_long/index.htm
- 上河文化, 大地座標系統漫談, http://www.sunriver.com.tw/grid_tm2.htm#a05
- 米的不落果（2004.05.20）TWD67與TWD97, http://blog.minstrel.idv.tw/2004/05/twd67-twd97.html
