Wednesday, 21 November 2001

Check out alb's new GPS Info Page! err... GPS = Global Positioning System - it's basically a system that helps you (with the help of this bunch of 24 satellites in space - of which you can only see 12 at most at one time since the earth is round and turns and turns.. durrh.. :p) to figure out where you are and where you're going with the help of exact coordinates which you detect with a GPS receiver. This tutorial is quite good for some basic understanding.

alb just tried to give me a crash course on navigation and datums and cassini numbers. All I can remember is, there are many datums out there. A datum is some kind of "model" that is used to match the location of features on the ground to coordinates on the map. Different maps may use different datums to plot the locations of places, hence, if you analyse any map data without knowing the datum, you may end up in an entirely different place (something like trying to find a location but using an entirely wrong scale e.g. cm vs metres). The use of Cassini numbers (e.g. x=28349.0000&y=31545.0000 for Orchard Cineleisure) is just another way of depicting x and y coordinates on a map. He also brought up something about diferent ways (I think, since I am getting confused) on how to flatten the earth. Using an example of an orange, we may choose to slice it North to South and hence lay it out like a flower, with the South Pole as the Centre. We can also just roll it flat out after one North-South slice. How the earth is flattened will affect ...err.. how ... oh dear, i don't remember anymore!!! :( knowledge leaks from my brain like mucus.. I think I need another lesson..

Anyhow, GPS is probably not very useful in Singapore since everyone navigates around Singapore by way of either MRT stations or MRT lines anyway.. I mean, when we are lost, we will probably just ask any nearby auntie or ah pek, "Ex-cue me hor, where is nearest M-Ah-T sta-sen har?". We'll never get lost, all thanks to our efficient and forward thinking Government. More Good Years!

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