General Mapping, Maps and GIS > Newbie's GIS

UTM and Peninsular Malaysia

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MyGIS:
Hello,

I am trying to set some coordinate systems to export sample data into KML. However KML file require you to set the coordinate systems or it would not work on your Google earth. My question is if we had to set UTM zone to our data; for Malaysia which zone would bethe most adequate? Judging from this picture extracted from this link: http://www.herpnet.org/herpnet/gbif/World_UTM_Map.pdf Peneinsular is divided by two zones: 47 and 48. This is a dilemma if we need to reset the UTM zone every time the data is on another zone of the map.



47 ? 48 ?

Noordin:
You are highlighting a universal problem with UTM projections i.e. trying to project 2 zones on a single projection. They are 3 main approaches currently adopted by users varying from easiest to most difficult.

a. Using the zone which has most data/land area. This is the normal approach by GIS users. The distortion will be most at the neighbouring zone which has less data. This approach is acceptable for mapping of small scale : 100K and above.
b. Reprojecting into another single projection. This is done with another projection acceptable for big areas (e.g. Lambert). This will minimize the distortion and it is most found at the boundary of the two zones.
c. Computing geodetically (2d or 3d). This is the most tedious method and even has been awarded MSc for attempts to do this. Data from both coordinates were computed to match the real coordinate on the earth surface in world coordinate system like WGS84 etc. This is not too accurate when there is no height information - thus the quality will depend on additional information like heights and availability of control points. This is good for scale 1:50K or larger

NA

MyGIS:
Hi,

I guess I agree. I just hope to see one day some paper on how to clear this confusion including all the RSO, Cassini and GDM2000 issues.

Thanks again.
Lyes

MyGIS:
Hi

Since precision is no cuicial for this case, I would be using WGS84 and LL84 where applicable. I believe it is sufficient.

Thanks again!

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