I have graphic files in vector format that I use the Polygon or
Prism commands of Povray to make images.  So far so good.  But I 
want to knock out the background as though the image is outlined so
I can use the image on a Web page and have the background of the Web
page show thru.

I hav'nt been having any luck doing this with no_background or a
transparent backgound.  Any suggestions?  Thanks for any ideas.
Sorry if this is a FAQ, I did'nt find it anywhere....

Glen

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Are you attempting this with Jpg? No, not likely if you even half know
what you're doing. Far as I know, and I know only a tiny bit, Gif is
the only thing that works for the typical browser. May be that Png
will sometimes if not always, I just don't know. Besides that, do not
use a 'sky_sphere' or 'background' color (nothing or a plane instead
for example) and try the alpha channel out if you can. The DOC will
explain somewhat. Others here probably have a better game plan, but
what I'd do is select a transparent color for a Gif in a image
processing program is all.

Bob

glenk10 <gle### [at] concentricnet> wrote in message
news:37C### [at] concentricnet...
> I have graphic files in vector format that I use the Polygon or
> Prism commands of Povray to make images.  So far so good.  But I
> want to knock out the background as though the image is outlined so
> I can use the image on a Web page and have the background of the Web
> page show thru.
>
> I hav'nt been having any luck doing this with no_background or a
> transparent backgound.  Any suggestions?  Thanks for any ideas.
> Sorry if this is a FAQ, I did'nt find it anywhere....
>
> Glen

Post a reply to this message

Well, it turns out that there are two Gif formats.... Gif87a and Gif89a.
Gif89a allows for a transparent background while Gif87a does not.

There is a program called giftrans.exe that converts the Gif87a to
Gif89a letting you specify what #rrggbb color will be transparent.

I found this program on a site at:
 http://members.aol.com/htmlguru/transparent_images.html 

Glen
glenk10 wrote:
> 
> I have graphic files in vector format that I use the Polygon or
> Prism commands of Povray to make images.  So far so good.  But I
> want to knock out the background as though the image is outlined so
> I can use the image on a Web page and have the background of the Web
> page show thru.
> 
> I hav'nt been having any luck doing this with no_background or a
> transparent backgound.  Any suggestions?  Thanks for any ideas.
> Sorry if this is a FAQ, I did'nt find it anywhere....
> 
> Glen

Post a reply to this message

I *had* to reply to this since I was just working on a webpage. What I did
for my transparent gifs was determine my dominant background color on my
webpage. Bluegreen. O.k. I then made the background in my pov scene a
similar color. I rendered my object using that background plus good
antialiasing. +a +r4 in the command line worked well for me. In PSP (Paint
Shop Pro) I selected the background color as the transparent color.

I was careful not to make any color within my object the same as the color
I was to make transparent.

The antialiasing made it to where my transparent gif blended with my
webpage's background. This method of making transparent gifs works best
for rounded objects, such as circles. It is also the all-around best way
to make a transparent gif that I have found.

Bob Hughes wrote:

> Are you attempting this with Jpg? No, not likely if you even half know
> what you're doing. Far as I know, and I know only a tiny bit, Gif is
> the only thing that works for the typical browser. May be that Png
> will sometimes if not always, I just don't know. Besides that, do not
> use a 'sky_sphere' or 'background' color (nothing or a plane instead
> for example) and try the alpha channel out if you can. The DOC will
> explain somewhat. Others here probably have a better game plan, but
> what I'd do is select a transparent color for a Gif in a image
> processing program is all.
>
> Bob
>
> glenk10 <gle### [at] concentricnet> wrote in message
> news:37C### [at] concentricnet...
> > I have graphic files in vector format that I use the Polygon or
> > Prism commands of Povray to make images.  So far so good.  But I
> > want to knock out the background as though the image is outlined so
> > I can use the image on a Web page and have the background of the Web
> > page show thru.
> >
> > I hav'nt been having any luck doing this with no_background or a
> > transparent backgound.  Any suggestions?  Thanks for any ideas.
> > Sorry if this is a FAQ, I did'nt find it anywhere....
> >
> > Glen

--
Samuel Benge

E-Mail: STB### [at] aolcom
Website: http://members.aol.com/stbenge

"Ni!"

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glenk10 wrote:

> I have graphic files in vector format that I use the Polygon or
> Prism commands of Povray to make images.  So far so good.  But I
> want to knock out the background as though the image is outlined so
> I can use the image on a Web page and have the background of the Web
> page show thru.
> 
> I hav'nt been having any luck doing this with no_background or a
> transparent backgound.  Any suggestions?  Thanks for any ideas.
> Sorry if this is a FAQ, I did'nt find it anywhere....

	I do not understand what you are trying to say. If you are
trying to create a POV output with a transparent background, an
interesting project but there are cheap to free utilities that
will do that for you. 

	Personally I can not imagine how any POV output could include a
transparent background after converted to GIF. I would say
impossible but that is a dangerous thing to say. But the
transparent color is an entry in the table header to the GIF
file. I know of no format conversion program that preserves and
translates it.

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What I've done is to do a quick render of my scene using a white background
and making sure all the objects are black.  From this image you can generate
a mask (using PSP or Photoshop).  Then, take your real image, put it on one
layer with your desired background on another, use the mask on the image,
and then merge the two layers.

--
Jim

Check out my web site  http://www.kressworks.com/
It'll blow your mind (politically), stimulate your senses (artistically)
and provide scientific insights that boggle the mind!

glenk10 <gle### [at] concentricnet> wrote in message
news:37C### [at] concentricnet...
> I have graphic files in vector format that I use the Polygon or
> Prism commands of Povray to make images.  So far so good.  But I
> want to knock out the background as though the image is outlined so
> I can use the image on a Web page and have the background of the Web
> page show thru.
>
> I hav'nt been having any luck doing this with no_background or a
> transparent backgound.  Any suggestions?  Thanks for any ideas.
> Sorry if this is a FAQ, I did'nt find it anywhere....
>
> Glen

Post a reply to this message