wgs66 transformation

[RoneyRodrigues]

Hello. I've received some data in WGS66 CoordSys, and can't find any model to transform it to WGS84. How can I do it?

Thanks,

Roney

[ChrisDonohue__GISP]

Not sure if this will give you what you need, but I found this on a quick web search:

AGD66 to WGS 84 (16)

(note:  Google seems to correlate WGS66 with AGD66, which may or may not be correct).

Some general information (but not the specific transformation):

World Geodetic System - Wikipedia, the free encyclopedia

Melita Kennedy

Edit: added more info

Chris Donohue, GISP

[MelitaKennedy]

I don't think they're the same. That is, there's definitely a World Geodetic System 1966 as well as Australian Geodetic Datum 1966. According to Wikipedia and ICSM, the ellipsoids are different too.

I don't think I've ever seen any transformations for WGS66. Possibly just define a custom one, but leave the parameters set to zeroes. That will model the difference between the flattenings of the two ellipsoids (so latitude values will change) but that's it.

Melita

[RoneyRodrigues]

Melita, you mean define a transformation changing only the ellipsoid, is that it?

Roney

[MelitaKennedy]

Yes, that's right, because we have no information on how the two ellipsoids (datums) are oriented relative to each other.

[RoneyRodrigues]

Sorry for bothering you guys again... I can't find a way to do it in ArcCatalog. I see the different methods (Geocentric Translation, Molodensky, etc) but have no idea of what to use. I have the numbers though for both ellipsoids (flattening and semimajor axis), but don't really know what to do with them...

Thanks for your help, Melita, and again, sorry for asking a perhaps uneducated question. I just can't find the answers anywhere I looked for.

Roney

[MelitaKennedy · Accepted solution]

Sorry, I should have been more clear. In the Create Custom Geographic Transformation tool, use the geocentric translation method, leave the parameters set to zeroes. It doesn't matter whether the source/target geogcs is WGS66 or WGS84. We'll apply it correctly.

Melita

[RoneyRodrigues]

Now it's clear, even your previous response seems clear now.

I was thinking about entering the ellipsoid parameters, but now I got it: ESRI already knows them. Just need to apply them in the transformation method with zeroes for the other parameters.

Makes total sense.

Thanks Melita!!

Roney