[Therion] 3D Models KML

[Bruce]

>Andrea wrote;
>I need a KML file to 
>be utilized into Google Earth.
>To give Geo references I thought I could 
>have inserted a single fixed station in one of the surveys, but the 
>outcome is still "data not georeferenced".

>I'm using utf-8 and nested surveys. 
	Not relevant.

>Is the fixed station needed in just one survey or each survey should have a
>fixed one? All surveys are connected by at least one station.
	So long as the surveys are connected, only one fixed point is
needed.

>Could you give me an axample of a georeferenced fixed station? I used the
>one available in the examples but I cannot make it work.

	An extract from one of my cave index.th files

#Set Co-ordinate System and Entrances
#====================================  
  centreline
    cs EPSG:27200 #NZ Map Grid 1949
    #Entrance co-ordinates
    fix a1 at a 2501402 6024490  725  5 5 10 #NZMG entrance by GPS
  endcentreline

First you need to specify a co-ordinate system with the cs statement, THEN
you need to fix a stations x,y,z position using that co-ordinate system.
See http://therion.speleo.sk/wiki/doku.php?id=ifl#coordinate_systems for
some epsg codes.
If you in fact have a number of entrances located by gps, there will of
course be misclosures, and you can (optionally)use estimates of the standard
deviation of the x,y,z error (say one third of the maximum credible error)
so that therion can better distribute the error.

Be aware that as soon as you specify a coordinate system, the declination
will be explicitly calculated by Therion, based on the position on the
earth, and the date of the survey (all surveys must have a date).
If you have ANY declination statements in ANY of your surveys, then the
declination statement will override the calculated declination for that
survey.  This is of course undesirable, and so you should weed out all
declination statements when using a cs statement.
(I would prefer it was the other way around - that cs would override
declination - but it is not)

Kml files are a quick and easy way to drape your cave over Google Earths 3d
terrain model, or see you cave 'mid-air' in 3d with absolute co-ordinates,
but alas Google Earth cannot look under the ground.
Loch is much better at that.  3D models for Loch are very easy to make
http://therion.speleo.sk/wiki/doku.php?id=ifl#terraintool_seems_to_be_an_eas
ier_alternative and if you have access to GIS or geo-referenced aerial
photos then you can make up your own graphics for Loch as good or usually
better than Google Earth.

Hope this helps.
Bruce