Re: Databases and Units

New Message Reply Date view Thread view Subject view Author view

Simon Mills (simon++at++wgs.estec.esa.nl)
Tue, 21 Dec 1999 09:33:27 +0100

Anthony Bavuso wrote:
>
> I have another question related to my previous question about open flight
> databases and units. Thanks to a very informative response from Calvin Lu,
> I can now at run-time ask a database what physical units it uses. But then
> my problem is what do I do with that information. I need to get all of the
> models to use one consistent physical unit so they all are of the
> appropriate sizes. There are several obvious possibilities.
>
> I could for example place a pfSCS node above my geometry scaling it to the
> desired units. But then would I take a run-time hit whenever I traverse my
> model scene graph to convert the model units into the desired units through
> the pfSCS node. This is of course undesirable.

You could add a pfSCS above your geometry as you say and then follow it
with

root = pfFlatten(0);
root = pfdCleanTree(root, NULL);

to apply the SCS transformation directly to the im-memory geometry and
then remove the, now redundant, identity pfSCS node. This will give you
what you want.

> What I would like to be able to do is once immediately after loading the
> model to alter the loaded geometry to use the desired units. In other words
> I would like to load into memory the geometry in its native units; scale it
> to my desired units; and then replace the original geometry in memory.
> Therefore every time I traverse the scene graph of the model it is
> inherently in the desired units.
>
> How would I do this?
  
Regards, Simon
________________________________________________________________________

Simon Mills
Silicon Worlds S.A.
c/o Modelling & Simulation Section (TOS-EMM) Tel: +31 (0)71 565 3725
European Space Agency (ESA/ESTEC) Fax: +31 (0)71 565 5419
Postbus 299, 2200AG Noordwijk e-mail: simon++at++wgs.estec.esa.nl
The Netherlands http://www.estec.esa.nl/wmwww/EMM
________________________________________________________________________

New Message Reply Date view Thread view Subject view Author view

This archive was generated by hypermail 2.0b2 on Tue Dec 21 1999 - 00:34:27 PST

This message has been cleansed for anti-spam protection. Replace '++at++' in any mail addresses with the '@' symbol.