Geolocation - translation attributes?

[maxB]

Noticed yesterday some translation attributes when a model has been geo located.

I geo-located a model to a location in the Netherlands. At that moment some keys and values are set (displayed here using an attribute plugin).

Just being curious: Whats the logic for the translation? Could it affect the accuracy of the units?

[DanRathbun]

That dictionary gets inserted with Google Earth terrain component information.

See this thread (and the related thread links in the right margin):

Geolocation has wrong elevation

Huck, you need to think of models as components. If you model a McDonald’s restaurant, later you’ll want to insert copies of it at many different elevations, all over the world. The model has a local coordinate system based upon it’s local datum (the model’s internal origin,) which is the insertion point for the model, as a component, into the world coordinate system. The elevation information, in the “GeoReference” attribute dictionary, “ModelTranslationZ” attribute is the z coordinate, where…

[maxB]

Dan, as always, thanks for the clarification.

So am I correct to assume the translation is just a reference to the North American Datum?
It has no function in SketchUp (if I don’t make models for Google Earth ea)?

The values could be replaced with some custom values if needed to reference them to the Dutch coordinate system without any problem?

Or are there uses for these translations within SketchUp itself?

[DanRathbun]

@maxB

So am I correct to assume the translation is just a reference to the North American Datum?

We do think so. However this data came from Google Earth. So the definitive answer would be in the GE API (I would think.)

@maxB

It has no function in SketchUp (if I don’t make models for Google Earth)?

Right, this data would be for later viewing you model in the Google Earth application. Google no longer accepts models for the online GE.

@maxB

The values could be replaced with some custom values if needed to reference them to the Dutch coordinate system without any problem?

I cannot say. I am not a “Google Eather”.

I would suspect that if you wanted to export to some other GIS system (besides Google Earth,) you would somehow need to convert the coordinates into the other system.
See API documentation: Geom::UTM and Geom::LatLong

If I was tasked to do it, I’d leave the GE “GeoReference” dictionary as is, and create another for the “Dutch” system with the converted coordinates, and a different but descriptive name. (At the very least, I’d create a backup copy of the original dictionary, so it could be restored later.)

@maxB

Or are there uses for these translations within SketchUp itself?

At the same time this “GeoLocation” dictionary is created, SketchUp sets the model’s internal location properties, for use with the native shadow engine. This data is kept in the model’s ShadowInfo hash. (I also think this can be changed manually later, which could invalidate the “GeoLocation” dictionary.)
See API documentation: Sketchup::ShadowInfo

SketchUp does not actually use the Z translation. It assumes sea level (it seems) for all shadow calculations [as of v16.] (Unless I suppose you use the Ocean bottom modeling extension and have the “model on sea floor” dictionary set true.)

From within SketchUp, you are actually within the edit context of the model as if it is a component. (Which it actually is to any external model “world”.)

[maxB]

Thanks for the answer, very helpful. Its all more clear now. Good suggestion to create a new dictionary.

[DanRathbun]

[quote=“DanRathbun, post:4, topic:21724”][quote=“maxB, post:3, topic:21724”]
The values could be replaced with some custom values if needed to reference them to the Dutch coordinate system without any problem?[/quote]

I would suspect that if you wanted to export to some other GIS system (besides Google Earth,) you would somehow need to convert the coordinates into the other system. See API documentation: Geom::UTM and Geom::LatLong
[/quote]

@maxB, found these also in the Ruby API:

Sketchup::Model.get_datum
Sketchup::Model.set_datum

Sketchup::Model.list_datums

Sketchup::Model.latlong_to_point
Sketchup::Model.point_to_latlong

Sketchup::Model.point_to_utm
Sketchup::Model.utm_to_point