VMD-L Mailing List

From: John Stone (johns_at_ks.uiuc.edu)
Date: Wed Sep 07 2016 - 13:12:29 CDT

It depends on which renderer you use. If you use Tachyon, you should
get a fully saturated color for high ambient values. The OpenGL
renderer takes a shortcut there for performance reasons, whereas
Tachyon does not...

Cheers,
  John

On Wed, Sep 07, 2016 at 05:53:01PM +0000, Vermaas, Joshua wrote:
> Hi John,
>
> I thought so too, but what you get for a pure ambient material is
> something gray, as though the colors aren't being applied with ambient
> light. Adding in some diffuse character appears to be essential to
> getting color that isn't white, black, or some shade of grey. Since
> diffuse responds to the angle of incident light, I don't think VMD is
> currently capable of colorful but perfectly flat shading.
>
> -Josh
>
> On 09/07/2016 11:32 AM, John Stone wrote:
> > Hi,
> > Aside from running Tachyon with the special flags, you could also
> > simply use a special material and disable shadows, and possibly
> > use orthographic projection get a flat unshaded 2D-like appearance.
> > If you make a material that has the diffuse and specular coefficients
> > set to zero, but retains a non-zero "ambient" term, when you render with
> > Tachyon or TachyonInternal you should get what appears to be an unshaded
> > rendering. Let us know if you have further questions.
> >
> > Cheers,
> > John Stone
> > vmd_at_ks.uiuc.edu
> >
> >
> > On Wed, Aug 31, 2016 at 04:37:42PM -0400, Ky Wildermuth wrote:
> >> Eric,A
> >> What works for me is rendering with Tachyon and choosing the option
> >> -lowshade such as in the example below:
> >> render Tachyon $filename "/vmd/vmd-1.9/lib/tachyon/tachyon_LINUXAMD64"
> >> $filename -lowshade -format BMP -o $filename.bmp
> >> This is a low quality rendering option that produces no shading at all (at
> >> least for the systems I have been working with). I am not sure if it would
> >> make a difference but I render the images using lights 0 and 1 on (and all
> >> others off) and I use the surf representation.
> >> I use this to quantify areas of selections based on color via a python
> >> computer vision script and it works well to identify entire selections of
> >> a specific color. You can try some other rendering options if this isn't
> >> exactly what you are looking for; there is a comprehensive list of Tachyon
> >> options on a previous post that you can find here:
> >> [1]http://www.ks.uiuc.edu/Research/vmd/mailing_list/vmd-l/23903.html
> >> I hope this helps.A
> >> -Ky
> >> On Wed, Aug 31, 2016 at 2:52 PM, Eric Smoll <[2]ericsmoll_at_gmail.com>
> >> wrote:
> >>
> >> Hello VMD community,
> >>
> >> VMD representations of chemical systems in with a style like VDW shows
> >> complex shading. This shading is dependent on the lighting scheme and
> >> shows the curvature of each atomic sphere. I am interested in generating
> >> an image with no shading. If the system contains two types of atoms
> >> coloured red and blue, the image should only contain pure red and pure
> >> blue at any viewing angle. I want an image with no contrast between
> >> atoms of the same type.
> >>
> >> Can this be done in VMD? If not, does anyone know of a visualization
> >> tool that might be able to accomplish this?
> >> Best,
> >> Eric
> >>
> >> References
> >>
> >> Visible links
> >> 1. http://www.ks.uiuc.edu/Research/vmd/mailing_list/vmd-l/23903.html
> >> 2. mailto:ericsmoll_at_gmail.com
> 

-- 
NIH Center for Macromolecular Modeling and Bioinformatics
Beckman Institute for Advanced Science and Technology
University of Illinois, 405 N. Mathews Ave, Urbana, IL 61801
http://www.ks.uiuc.edu/~johns/           Phone: 217-244-3349
http://www.ks.uiuc.edu/Research/vmd/