[Chimera-users] Linewidth in images

Eric Pettersen pett at cgl.ucsf.edu
Tue Dec 22 10:48:26 PST 2009

Hi Thomas,
	To expand on Greg's explanation a little: many graphics cards/drivers  
have a maximum line width they are capable of drawing.  When you  
render an image with supersampling N, each "tile" is drawn N times  
larger than normal and then sampled back down to its final size.  This  
greatly reduces the "stair stepping" on the edges of ribbons and so  
forth since the pixels in the final image are a blend of NxN original  
pixels.  This also means that lines have to be drawn N times thicker  
in each tile so that they are the right size in the final image.  If  
that thickness is beyond the capabilities of your graphics card/driver  
then those lines will look thinner than they should in the final image.
	For an image of the size you're making (4096x3072) you probably don't  
need any supersampling unless it's going to be displayed at poster  
size.  In the image-saving dialog at the bottom it will say what the  
maximum line width you can use in the Chimera window without any  
reduction in the final image at your current supersampling setting.   
If that information text is colored red, then the line thickness in  
the image will be less than the current line thickness in the Chimera  
window.  So you could experiment with what maximum supersampling  
setting you could use without the lines thinning in the image.


                         Eric Pettersen
                         UCSF Computer Graphics Lab

On Dec 22, 2009, at 10:01 AM, Greg Couch wrote:

> The maximum line width depends on your graphics driver.  When you  
> save an image with the Save Image dialog, the bottom line above the  
> buttons show the "effective maximum line width".  If you reduce the  
> size of the image or reduce the amount of supersampling, then you  
> can have larger lines.
> 	- Greg
> On Tue, 22 Dec 2009, Dipl.-Ing. Thomas Mitterfellner wrote:
>> Hello!
>> I am making large images (4096x3072) which use silhouette edges and  
>> dashed wire-style bonds. When I increase the width of the  
>> silhouette edges, I do see that on the screen, but the output image  
>> turns out the same regardless of this setting. The same is true for  
>> my dashed bonds. Is this some issue of graphics card (GeForce 6200)  
>> or am I missing something?
>> Thank you,
>> Thomas
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