[Users] Version 3.0.2 and shading

[Bert Bril]

Dear users,

In 3.0, for the first time, OpendTect can use 'shading' to improve
graphical performance. This means that some calculations are done on the
graphics card rather than on the CPU.

We found that many graphics cards are capable of shading nowadays.
Rather old cards do not support it and report this to OpendTect which
then won't even try to use it. Good new cards (like the nVidia 6000
series) report they support it and actually support it well. The snag is
that some cards of about 1-2 years old do give problems. These report
that they support shading, but they support only part or they support it
so badly that the system almost stops. In particular shading for volume
rendering gives more problems than 'ordinary' shading.

To handle this, we have set defaults as follows:
* If the card says it supports shading, we use it
* Even if the card says it supports shading, we do not use it for volume
rendering

In practice, there were no problems for most graphics cards we tested.
The most common problem is that you can get colorless elements like
inlines, time slices, horizons. Then try visiting the menu
'Utilities-Settings-Look&Feel' and disable the shading altogether
(consider buying a new graphics card though).

On the positive side, if all works fine, you can try improving the
volume rendering speed and quality by enabling shading for volume
rendering in the same dialog; it's worth a try because it really makes
quite a bit of difference.


Bert Bril

-- 
-- Bert Bril / OpendTect developer at dGB
-- Nijverheidstraat 11-2, 7511 JM Enschede, The Netherlands
-- mailto:Bert.Bril at opendtect.org , http://opendtect.org
-- Tel: +31 534315155 , Fax: +31 534315104