VMD-L Mailing List

From: Olaf Lenz (olenz_at_fias.uni-frankfurt.de)
Date: Sun Apr 29 2007 - 03:31:34 CDT

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Hello!

Axel Kohlmeyer wrote:
> VC> I was trying to render an image using depth cueing (vmd 1.8.6). However,
> VC> even if I have all lights on, the image remains very dark ...

I think I understand what Vlad means, as the effect actually kept me
from using depth cueing even though it is useful in many cases. The
problem he describes is, that the "fog" starts right at the eye, so that
even the parts closest to the observer can already look cued and faded.

Quick answer: to make the image less faded, choose the translation mode
(press 't'), press and keep the middle mouse button pressed, and move
the mouse left or right. This will probably do what you want.

Longer answer:
The key is to realize that there is a difference between scaling the
molecule and translating the molecule in and out of the screen.
When using the mouse wheel or the scaling mode (press 's'), you "scale"
the molecule. This can be thought of as using a camera and zooming in or
out. As for the depth cueing, the amount of fog between the eye and the
molecule does not change, therefore the image looks still as faded as
before.
To "translate" the molecule, choose translation mode (press 't'), press
the middle mouse button and keep it pressed, and move the mouse left or
right. This will move the camera position in and out. When you are
closer to the molecule, there is less fog, and the colours look less faded.

In fact, this has very much confused me at first, as I'm a fan of the
orthographic projection mode. When cueing is turned off, translating the
molecule in and out the screen has no visible effect at all. Only when
cueing is turned on, the amount of fog is changed, but the size of the
image is still constant. This is something that would be nice for the docs!

Olaf

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