15/04/2013

Is there a state boundary issue?

Perlis-Kedah border
Zoomed in
Perlis User Defined Coordinate System
Kedah User Defined Coordinate System
Kelantan-Terengganu border
Zoomed in
Malacca-Johore border
Zoomed in
Is there a state boundary issue?

I have often been told by many that the boundary between state cadaster maps do not dovetail because each state uses different reference points for their respective cadaster. It seemed logical so I never care to question it furthermore, was mentioned by people more experienced than me. However, today, since I as usual got nothing better to do, gave it a try and activated 6 state cadaster maps (with their User Defined Coordinate System NOT WGS 84 projection) as shown above where QGIS showed each had different user defined coordinate system but unlike what people said, all fit well along their borders. So I asked myself 'Where did I go wrong?' Firstly, I did not try it out myself to see that the proof was in the pudding. Secondly, I did not question people I thought were 'experts' and more experienced than me. Thirdly, I never thought that JUPEM in coming up with respective projection for state cadaster plans, had aligned them properly. Now I believe the moment the original JUPEM plan is converted away from the user defined coordinate system, say, "WGS84", be prepared for errors where cadaster or landuse plans do not converge and dovetail with their adjacent neighbour. For reference, I also happened to get JUPEMs projection parameters from one of my staff who obtained them directly from the horse's mouth as below:

"--- Malaysia RSO Projection ---"
"Peninsular Malaysia", 7, 47, 7, 105.236442875, -0.0001719694, 323.130102389, 0.99984, 804671.29978, 0
"Sabah & Sarawak", 7, 96, 7, 115.0, 4.0, 53.3158204722, 0.99984, 2590476.872, 5442857.653, 0 

"--- Malaysia State Cassini-Soldner Systems ---"
"Cassini-Soldner Johor", 30, 47, 7, 103.5627583,2.0425,0,0
"Cassini-Soldner NS/Melaka", 30, 47, 7, 101.9411667,2.712283333,-242.0048934,-948.546528
"Cassini-Soldner Pahang", 30, 47, 7, 102.4361778,3.710972222,0,0
"Cassini-Soldner Selangor", 30, 47, 7, 101.5082444,3.680344444,-21759.43848,55960.90576
"Cassini-Soldner Kelantan", 30, 47, 7, 102.1772917,5.893922222,0,0
"Cassini-Soldner Terengganu", 30, 47, 7, 102.8952083,4.946141667,0,0
"Cassini-Soldner Perak (Revised)", 30, 47, 7, 100.8167667,4.859380556,0,133453.6688
"Cassini-Soldner Penang", 30, 47, 7, 100.3458694,5.421325,0,0
"Cassini-Soldner Kedah/Perlis", 30, 47, 7, 100.6375944,5.965147222,0,0
"Cassini-Soldner Singapore", 30, 47, 7, 103.853, 1.287639, 30000, 30000

2 comments:

  1. Replies
    1. I still don't have an original raster map to work on i.e. can only activate with "Add Raster Layer" icon.

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