Converting between WGS60 & WGS84 and between AGD66 & GDA94?

[Son of a Beach]

im glad you understand it, cause i did a degree on it and still dont understand it. i forwarded the link to Bit Map to my mates who have an Iphone, it looks good.

heheh... it sure is complicated. However, my understanding is really very shallow. There's some very complex maths involved in actually doing the transformations, and that is way over my head. I found some good thorough mathematical algorithms to do the job, and converted them to computer code, and low and behold it works. But it feels like black magic to me.

It's a bit like those computer programs that do something and then come back with the response, "Succeeded!". The exclamation mark seems to imply that success wasn't actually expected, and it's a miracle that it worked at all. That's kind of how I feel about my own software's ability to convert WGS datum's latitude/longitude references into any other datum's UTM grid references. Of course, this all happens behind the scenes (literally) of the map view, and the user never gets to see a surprised, "Succeeded!" message. They just see their path being plotted across the maps.

[MJD]

Did you come across this page:

http://www.uwgb.edu/dutchs/usefuldata/UTMFormulas.HTM

And yes, some of the maths is very convoluted.

[bahkyp]

Did you come across this page:

http://www.uwgb.edu/dutchs/usefuldata/UTMFormulas.HTM

"Calculating the arc length of an ellipse involves functions called elliptic integrals, which don't reduce to neat closed formulas" - **Twitch** almost forgot Power Series, Jacobian functions, Taylor series et al. **Twitch**. With these you should drop terms when there become "bugger all squared" and save on calculation, this will be a source of error but will be minimal compared to machine error. (recurring calculations like these generally are accurate to 9-12 significant figures max using 10^15 precision) 9 sig figures on earth scale is about +-0.1m

Looks good. (read; yep, that's a power series. no, I don't want to check it) Just remember there is the additional step of ADG66 to WGS84/GDA94 in the UTM ADG66 to UTM GDA94 conversions.

He also uses a northern hemisphere UTM diagram. Just flip vertically for SH. Oh and watch your signs.

Michael.

[AnthonyD]

On this topic, you may find the AusDatumTool quite useful:
http://www.binaryearth.net