"EagleSun" <nomail@nomail> wrote in message
news:web.45d131842a2b82398fafdc490@news.povray.org...
> "EagleSun" <nomail@nomail> wrote:
> > Here is the image with normal render.
>
> Here it is again when I added only the "+UA" option in the command line.
>
>
> So.. what's wrong with this?

I don't know, what is wrong with it? I opened it up in Gimp and it
definately had a transparent "background". The earth itself isn't
transparent.

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EagleSun wrote:
> "EagleSun" <nomail@nomail> wrote:
>> Here is the image with normal render.
> 
> Here it is again when I added only the "+UA" option in the command line.
> 
> 
> So.. what's wrong with this?
> 
	Looks fine to me... What were you expecting?

		Jerome
- --
+------------------------- Jerome M. BERGER ---------------------+
|    mailto:jeb### [at] freefr      | ICQ:    238062172            |
|    http://jeberger.free.fr/     | Jabber: jeb### [at] jabberfr   |
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"Ross" <rli### [at] speakeasynet> wrote:
> "EagleSun" <nomail@nomail> wrote in message
> news:web.45d131842a2b82398fafdc490@news.povray.org...
> > "EagleSun" <nomail@nomail> wrote:
> > > Here is the image with normal render.
> >
> > Here it is again when I added only the "+UA" option in the command line.
> >
> >
> > So.. what's wrong with this?
>
> I don't know, what is wrong with it? I opened it up in Gimp and it
> definately had a transparent "background". The earth itself isn't
> transparent.

Very strange you don't see a problem.... I see a THICK BLUE circle around
the earth on the version I created with the "+UA" option.  When I tried
converting it to PPM format, the THICK BLUE circle was included.

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The atmoshpere looks a bit thick, but it's
only 3 or 4 pixels, and fades opaque.
The atmosphere isn't usually sitting there with
a white backdrop.
Here's a link to an OK moonrise pic.
http://www.space.com/php/multimedia/imagegallery/igviewer.php?imgid=55&gid=4
After looking at that, I'd think the air in your
model should be clearer a bit.

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> Very strange you don't see a problem.... I see a THICK BLUE circle around
> the earth on the version I created with the "+UA" option.  When I tried
> converting it to PPM format, the THICK BLUE circle was included.

If you take the +UA version and put it on a black background in Photoshop,
it's nearly identical to the original (some pixels around the edge are off
by a very slight amount (7 or 8 out of 255), which might be caused by how
POV-Ray handles transparency on emissive media). The majority of the visible
difference is caused by the fact that you've displayed the second version on
a grey background, which makes the blue ring around the earth more visible
(probably mostly because of your monitor's gamma.)

 - Slime
 [ http://www.slimeland.com/ ]

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EagleSun wrote:
> Very strange you don't see a problem.... I see a THICK BLUE circle around
> the earth on the version I created with the "+UA" option.

That's called an "atmosphere", and it's present in both versions of the 
picture.  Try layering it over a background to see how it acts; the 
background will be filtered through it.

...Chambers

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use white background

or use green

AND  set you 'right color transparency ' if you use PSP ..




news:web.45d12f3355e01ed18fafdc490@news.povray.org...
> Here is the image with normal render.
>
>


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----

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Preview of image 'Image1.png'

"Slime" <fak### [at] emailaddress> wrote:
> > Very strange you don't see a problem.... I see a THICK BLUE circle around
> > the earth on the version I created with the "+UA" option.  When I tried
> > converting it to PPM format, the THICK BLUE circle was included.
>
> If you take the +UA version and put it on a black background in Photoshop,
> it's nearly identical to the original (some pixels around the edge are off
> by a very slight amount (7 or 8 out of 255), which might be caused by how
> POV-Ray handles transparency on emissive media).

Hmm... I have GIMP... perhaps you can show me how in GIMP?  (I don't have
Photoshop.)

> The majority of the visible
> difference is caused by the fact that you've displayed the second version on
> a grey background, which makes the blue ring around the earth more visible
> (probably mostly because of your monitor's gamma.)

Grey?  As in Grey and white checkerboard?  How do I change the background?
I didn't modify the source when I re-rendered using the "+UA" option.

And, yes, the atmosphere is very thick by design, so that I'll have plenty
of space to fade away the atmosphere without having any appearance of "hard
cut-off".

In this "game" I was playing, I was hoping to produce 2 identical images,
where 1 would have an alpha channel.  But I'm not convinced that I have 2
identical images.  Would like to see someone take the image with alpha,
remove the alpha and see if it looks identical to the first... and tell me
what software you used to do it (and I hope you mention "GIMP" :) )

Here's what I get when I attempt to remove the Alpha.  I get this using
XnView and NetPBM.  Obviously it's not identical to the original.  Maybe I
need more explanation?

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EagleSun wrote:
> "Slime" <fak### [at] emailaddress> wrote:
>>> Very strange you don't see a problem.... I see a THICK BLUE circle around
>>> the earth on the version I created with the "+UA" option.  When I tried
>>> converting it to PPM format, the THICK BLUE circle was included.
>> If you take the +UA version and put it on a black background in Photoshop,
>> it's nearly identical to the original (some pixels around the edge are off
>> by a very slight amount (7 or 8 out of 255), which might be caused by how
>> POV-Ray handles transparency on emissive media).
> 
> Hmm... I have GIMP... perhaps you can show me how in GIMP?  (I don't have
> Photoshop.)
> 
	Create a new image with the same dimensions. Fill it with black.
Open your alpha image, select everything (Ctrl-A), copy it and paste
it on the black image...

		Jerome
- --
+------------------------- Jerome M. BERGER ---------------------+
|    mailto:jeb### [at] freefr      | ICQ:    238062172            |
|    http://jeberger.free.fr/     | Jabber: jeb### [at] jabberfr   |
+---------------------------------+------------------------------+
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"EagleSun" <nomail@nomail> wrote:
> "Slime" <fak### [at] emailaddress> wrote:
> > If you take the +UA version and put it on a black background in Photoshop,
> > it's nearly identical to the original (some pixels around the edge are off
> > by a very slight amount (7 or 8 out of 255), which might be caused by how
> > POV-Ray handles transparency on emissive media).
>
> Hmm... I have GIMP... perhaps you can show me how in GIMP?  (I don't have
> Photoshop.)

Open your alpha image in The Gimp, add a layer and move it underneath your
alpha image, fill the blank layer with black. Now open your other Earth
picture, either through dragging its icon to the layer stack window or by
opening it in its own window and then dragging its single layer onto the
other alpha picture. Now you have three layers, put the
Earth-with-black-background layer on top of the layer stack. Just above it
there's a drop-down menu with "Normal" written on it; click on it and
select "Difference" (make sure the Earth with background layer is
selected), you should see almost all black. For ease of use, highlight the
alpha layer, select the magic wand and click anywhere on the 'space', so
that you have a selection outlining the Earth. Now pick the eyedropper and
check the RGB values. There's a zone with over 30 in R and G in the bottom
of the Earth (huh I can't really call it South Pole, can I?). The rest is
either correct or 7-8 off in places. I don't know what causes these
discrepancies but my money is on assumed gamma stuff.

> In this "game" I was playing, I was hoping to produce 2 identical images,
> where 1 would have an alpha channel.  But I'm not convinced that I have 2
> identical images.  Would like to see someone take the image with alpha,
> remove the alpha and see if it looks identical to the first... and tell me
> what software you used to do it (and I hope you mention "GIMP" :) )
>
> Here's what I get when I attempt to remove the Alpha.  I get this using
> XnView and NetPBM.  Obviously it's not identical to the original.  Maybe I
> need more explanation?

The Alpha channel makes part of the color transparent, by filtering whatever
it is applied on, not unlike transmit in POV-ray. If you remove it from your
pic, unsurprisingly, you'll get the full color that is currently filtered.

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