VMD-L Mailing List

From: Axel Kohlmeyer (akohlmey_at_cmm.chem.upenn.edu)
Date: Sun Apr 29 2007 - 12:43:19 CDT

On Sun, 29 Apr 2007, Olaf Lenz wrote:

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OL> Hello!
OL>
OL> Axel Kohlmeyer wrote:
OL> > VC> I was trying to render an image using depth cueing (vmd 1.8.6). However,
OL> > VC> even if I have all lights on, the image remains very dark ...
OL>
OL> I think I understand what Vlad means, as the effect actually kept me
OL> from using depth cueing even though it is useful in many cases. The
OL> problem he describes is, that the "fog" starts right at the eye, so that
OL> even the parts closest to the observer can already look cued and faded.

which, if correct, would (again) prove, that the kind of help one
can provide depends very much on asking the right questions and
providing an accurate descriptiong of the problem. 'render' implies
for me using an external renderer and 'display' would imply the default
display.
 
OL> Quick answer: to make the image less faded, choose the translation mode
OL> (press 't'), press and keep the middle mouse button pressed, and move
OL> the mouse left or right. This will probably do what you want.

in order to add any useful content, i'd also like to draw your attention
to the Display Settings dialog (and the corresponding script commands)
that allow to fine tune the settings for depth cueing, particularly
the cue density.

cheers,
   axel.

OL>
OL> Longer answer:
OL> The key is to realize that there is a difference between scaling the
OL> molecule and translating the molecule in and out of the screen.
OL> When using the mouse wheel or the scaling mode (press 's'), you "scale"
OL> the molecule. This can be thought of as using a camera and zooming in or
OL> out. As for the depth cueing, the amount of fog between the eye and the
OL> molecule does not change, therefore the image looks still as faded as
OL> before.
OL> To "translate" the molecule, choose translation mode (press 't'), press
OL> the middle mouse button and keep it pressed, and move the mouse left or
OL> right. This will move the camera position in and out. When you are
OL> closer to the molecule, there is less fog, and the colours look less faded.
OL>
OL> In fact, this has very much confused me at first, as I'm a fan of the
OL> orthographic projection mode. When cueing is turned off, translating the
OL> molecule in and out the screen has no visible effect at all. Only when
OL> cueing is turned on, the amount of fog is changed, but the size of the
OL> image is still constant. This is something that would be nice for the docs!
OL>
OL> Olaf
OL>
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-- 
=======================================================================
Axel Kohlmeyer   akohlmey_at_cmm.chem.upenn.edu   http://www.cmm.upenn.edu
   Center for Molecular Modeling   --   University of Pennsylvania
Department of Chemistry, 231 S.34th Street, Philadelphia, PA 19104-6323
tel: 1-215-898-1582,  fax: 1-215-573-6233,  office-tel: 1-215-898-5425
=======================================================================
If you make something idiot-proof, the universe creates a better idiot.