topic Re: wgs66 transformation in Coordinate Reference Systems Questions

wgs66 transformation

RoneyRodrigues — Mon, 29 Feb 2016 15:45:34 GMT

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

Re: wgs66 transformation

ChrisDonohue__GISP — Mon, 29 Feb 2016 16:07:16 GMT

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

Re: wgs66 transformation

MelitaKennedy — Mon, 29 Feb 2016 19:06:28 GMT

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

Re: wgs66 transformation

RoneyRodrigues — Mon, 29 Feb 2016 20:30:49 GMT

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

Roney

Re: wgs66 transformation

MelitaKennedy — Tue, 01 Mar 2016 22:11:02 GMT

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

Re: wgs66 transformation

RoneyRodrigues — Fri, 11 Mar 2016 14:54:10 GMT

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

Re: wgs66 transformation

MelitaKennedy — Fri, 11 Mar 2016 19:33:34 GMT

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

Re: wgs66 transformation

RoneyRodrigues — Sat, 12 Mar 2016 17:57:39 GMT

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