How To Deal With An Unusual Datum?

[davester]

I'm off on holiday to Gran Canaria next week and have just sat down to print off the details of the caches with the intention of marking them on the map as I go along. However, I soon realised that the co-ordinates were somewhat askew, and upon checking the datum my fears were realised.

 

The map datum is a Canary Island exclusive one, named REGCAN 95 and is not supported (surprise!) by my Geko 201.

 

Is there an easy way to convert to be able to plot my caches on the map. Or am I going to have to use some guesswork based on the best Mapquest maps?

[+wimseyguy]

Don't ask her/him out again.

Oh I'm sorry I thought the topic said date'm.

[Wild T2]

I have never used this program (never had a need to), but it is my understanding that it can translate to and from just about every datum, map projection, and coordinate system that you are likely to encounter in the world.

 

http://earth-info.nga.mil/GandG/geotrans/

[davester]

There's always one......!

 

[+greende]

Don't ask her/him out again.

Oh I'm sorry I thought the topic said date'm.

[davester]

I have never used this program (never had a need to), but it is my understanding that it can translate to and from just about every datum, map projection, and coordinate system that you are likely to encounter in the world.

 

http://earth-info.nga.mil/GandG/geotrans/

Cheers. About to take a look at that.

 

There is some information on the map,

 

"The mapping has been done using REGCAN 95 geodetic reference system for the Canary archipelago i.e. origin geocentre, fundamental point Maspalomas on Gran Canary, coordinates ITRS94 epoch 94.9, associate ellipsoid GRS80. "

 

Anyone know of a way to input the datum info into the Geko 201 user datum?

[+Rakusan]

ITRS sounds like International Terrrestrial Reference System - which is a refinement of WGS 84. It's very likely that any coordinates on that datum will be within a meter or so of the WGS 84 coordinates - too close for you to measure with a Geko 201.

 

GEOTRANS 2 shows 'Pico de las Nieves' as the older geodetic datum for the Canary Islands. It's described as based on the International ellipsoid, which was used in Europe, western Asia, and north Africa until the GPS era.

 

Just as a guess, REGCAN 95 might be a "geoidal island" fitted to mean sea level in the Canarias. In any case, I doubt if the difference between their horizontal datum and WGS 84 will be enough to notice on anything less than a surveying rig.

 

Hope this helps ... Rakusan

(Geodesy is part of my profession. It's not a fetish.)

[davester]

Thanks for your thoughts Rakusan.

 

I've been trying to find out more and have noticed by accident that although the D° M.M co-ords for the caches I plan to visit are hopelessly inaccurate with respect to the latitude, both the northings and eastings on the UTM scale seem to be spot on, using the the WGS84 datum.

 

Anyone any thoughts why this should be?

[dave and jaime]

I'm off on holiday to Gran Canaria next week and have just sat down to print off the details of the caches with the intention of marking them on the map as I go along. However, I soon realised that the co-ordinates were somewhat askew, and upon checking the datum my fears were realised.

 

The map datum is a Canary Island exclusive one, named REGCAN 95 and is not supported (surprise!) by my Geko 201.

 

Is there an easy way to convert to be able to plot my caches on the map. Or am I going to have to use some guesswork based on the best Mapquest maps?

if your geko has the ability to accept a use grid/datum than this would be the best route. there are anumber of sites that have posted the parameters for individual datums. if you cant find a complete listing i have one and can email it to you.

[davester]

Thanks, a list would be very useful as the ones I have found don't include this datum.

[dave and jaime]

Thanks, a list would be very useful as the ones I have found don't include this datum.

unfortunately i shouldve checked my list before saying i had it.

 

however here is a link to the listing i use. maybe the datum youre about to use may have an equivilancy on the list.

 

if you find anymore post back.