"Jaime Vives Piqueres" <jai### [at] ignoranciaorg> wrote in message
news:421451bc@news.povray.org...
> Chris Cason wrote:
> > The primary results for POVCOMP 2004 are ready.
>
>    Thanks for all the effort, Chris and all the rest of the team, judges
> and sponsors.
>
>    Now to figure some excuse to not go to work this morning, so I can
> enjoy viewing all those superb images, and then browsing the entire
> zazzle site... :)
>
> --
> Jaime

I just have to say that some aspects of your scene are mind boggling
realistic. The water bottle looks totally real. The clock and the spices on
top of the over... real. The drapes over the window, and the tiles are
perfect.

really, the water bottle, even if just a mundane everyday object, stands out
as being utterly real. fantastic work.

-r

"Jim Charter" <jrc### [at] msncom> wrote in message
news:421600a9$1@news.povray.org...
> Lance Birch wrote:
>
> > I think the biggest way to improve the image (in my opinion) is with the
> > lighting.  Right now the image appears a little flat and therefore it's not
as
> > dramatic as it could (and deserves to) be.  I'd really love to see this
scene
> > taken further!  There's no reason to stop now since there's already been so
much
> > work put into it; just a few changes to the lighting of the scene could make
a
> > huge difference I think.  If it was my scene I'd probably drop the camera
height
> > a tiny bit as well, or if not, introduce some focal blur to separate the
> > background from the main subjects (heh, yes, I know... rendertime++)
> >
>
> Thankyou for the insights, and even more, the spirit of support.  In a
> nutshell, it is hard for me to give up on the backlighting.  The
> original vision was of the scene taking place in a gloom set against a
> backdrop of turgid, oppressive light, screened by a silhouette of jungle
> growth. That is not quite how the scene turned out, but I still cling to
> certain of its original aspects. I will try to swallow my conceptual
> arrogance and, if I ever find that new level of maturity, try the scene
> with some different lighting.  Parenthetically, I believe I have run up
> against this difficulty in contests before.  I think I just have a taste
> for the slightly flattening effect of halflight and backlighting that is
> a little at odds with the raytracing aesthetic. So I also wonder if some
> adjustment of the finishes might bring up the textures and still give me
> that backlight.

Well, I don't mean to say "abandon your concept"... just that it needs some
tweaking to get it to work how you want it to :)  A lot of the problems I find
with lighting are due to contrast.  Our eyes detect contrast before anything
else, so it follows that an image that lacks contrast is not as easy to view
(objects don't stand out as much, or the image looks flat).  However, you can
still have a backlit or post-sunset scene and still have contrast.. the key is
not introducing "global contrast", but instead introducing "localised contrast".
That is, contrast between the different objects and the background, not an
increase in contrast of the entire image.

To understand the difference between local and global contrast better, load your
image up in a graphics package like Photoshop or similar that supports a live
Histogram view.

1. apply say +10% Contrast to your image and watch what happens to your
Histogram... the low ends will move lower, and the high ends will move higher.
This changes the look of your image overall (and suddenly it doesn't look like
the kind of lighting you want, but the objects are separated better from the
background).

2. go back to the original image without the Contrast added, and this time apply
an Unsharp Mask to the image with a radius of 20 pixels and an amount of 20%
(with no threshold), and watch how your Histogram... you'll see that it doesn't
change very much at all (thus retaining the overall look of the image), however
the objects are separated better from the background and the image appears
slightly more "alive".  The reason is that localised contrast has been
introduced.

This is basically what our eyes do when we look at something in real life... as
we move our eyes, they adjust to the localised brightness level of what we're
viewing to create more contrast locally.  In other words, everywhere we look
there's contrast created locally, even though if we stood back further and
looked at the scene overall with relaxed eyes, it might not have a lot of
contrast and details would be harder to make out.

So the trick is to try to get the same thing to happen straight out of POV-Ray,
and the easiest way of achieving localised contrast/separation between objects
(the grass is a good example of where this is needed as right now it's difficult
to gauge its depth due to the consistency of luminosity) is to introduce
shadows, or use other tricks like fog to tint objects that are at great
distances (thus separating foreground from background), or use depth of field.
So in other words, we have to cheat a bit :)  You could make the backlighting
even more dramatic, and introduce a fill light to ensure the subjects are still
lit appropriately (in real life our eyes do a good job of simulating fill lights
in such conditions of backlighting, again this is the localised contrast
syndrome).

Another good way of testing where your image could use additional localised
contrast (or different lighting, fog to separate background/foreground, etc) is
to simply blur your eyes while looking at it; are the object depths still
obvious or do they appear to be floating in seas of colour?

I hope this all makes some sense :)

What I'm getting at is:  you can still retain the look of your image, but to do
so and still make the objects stand out you need to either introduce localised
contrast in the lighting of the objects, or use another technique to separate
the different objects from the background (by introducing a fog to tint the
background, or by using depth of field, etc).

Lance.

thezone - thezone.firewave.com.au
thehandle - www.thehandle.com

news:42161482@news.povray.org...

> To understand the difference between local and global contrast better,
load your
> image up in a graphics package like Photoshop or similar that supports a
live
> Histogram view.

Do you think that you could edit this a little bit and add it to the wikipov
site ? The fact is that *** many *** POV-Ray pictures suffer from contrast
issues and that this little tutorial you just wrote could be very handy.
It could go there:
http://www.wikipov.org/ow.asp?ArtTips

G.


-- 

**********************
http://www.oyonale.com
**********************
- Graphic experiments
- POV-Ray and Poser computer images
- Posters

"Lance Birch" <-> wrote in message news:42161482@news.povray.org...

<snip>

I don't know about anyone else, but I found your post to be a great 
resource.  It's a very common problem.  What we "see" versus what we 
"perceive" are often completely different.

I noticed some time ago that my image lacked good contrast, but I wasn't 
sure what I could do about it.  Thanks for the information!  I hope I'm not 
the only one that just learned something here.  :-)

-- 
Jeremy
www.beantoad.com

"Gilles Tran" <tra### [at] inapginrafr> wrote in message
news:421616f4@news.povray.org...

> news:42161482@news.povray.org...
>
> > To understand the difference between local and global contrast better,
> load your
> > image up in a graphics package like Photoshop or similar that supports a
> live
> > Histogram view.
>
> Do you think that you could edit this a little bit and add it to the wikipov
> site ? The fact is that *** many *** POV-Ray pictures suffer from contrast
> issues and that this little tutorial you just wrote could be very handy.
> It could go there:
> http://www.wikipov.org/ow.asp?ArtTips

I've never posted to a wiki before so if you could explain what I have to do
(and what I shouldn't do) I'll edit something together and put it online :)

Lance.

thezone - thezone.firewave.com.au
thehandle - www.thehandle.com

Lance Birch wrote:

...

Thanks for taking the time. A beautiful succinct discussion. I really 
appreciate it. I did understand some things about local vs global 
contrasts though not by those terms.  I would have termed the 
adjustments we make in "real world" perception, that you credit to the 
eyes, "haptic" perception, and viewed it as an extension of our 
"embodied" consciousness.*  So generally I think that the eyes adjust to 
optimise a view of what the mind-body already knows is there.  So when I 
painted I tended to incorporate those adjustments but never thought of 
it as "fill light" but rather as "haptic" knowledge. If fact for years I 
painted very, very dark, close-toned paintings, where I would use tricks 
of paint handling to make objects more or less distinct.** I'm a big 
admirer of Whistler and Rosseau, in addition to Morandi. So your 
discussion helps simplify things tremendously and helps me think in 
terms of digital methods and empirical light gathering. (And I didn't 
know at all about the PS Unsharp Mask.  Really anxious to explore that.)

Thanks again.  You really helped me simplify my thinking about this.  I 
almost mentioned in my previous post, that I think one of my big 
problems with lighting is that I don't have strong sense of what looks 
correct.  I tend to accept what the raytracer gives me like I accept 
what the camera gives me and am reconciled to the idea that neither is 
going to look like what an embodied experience of the same scene would 
be anyway.  There is so damned much to learn!

In general I might have subconsciously understood the issue but I was 
mired in the idea that there might be a somehow "honest" way of 
achieving the result, say, if I just understood Jaime's lighting system 
better.  I've to laugh at this because I have also felt that *I* was one 
of the foremost proponents of raytracing is an medium rooted in artifice.

-Jim


*Merleau-Ponty reigned when I was in college.

** You might appreciate that this took me to truly obsessive lenghts 
when it came to trying to document my paintings photographically for my 
portfolio.

news:42162096$1@news.povray.org...
> I've never posted to a wiki before so if you could explain what I have to
do
> (and what I shouldn't do) I'll edit something together and put it online
:)

It's very easy: go to the main page http://www.wikipov.org/ and then to the
sandbox. Click on "Edit this page" (you'll have to log-in with the password
given on the front page) so that you can familarise quickly with the syntax.
After that go to add/modify what you want. The ArtTips page is probably the
best place to put a link to (and then create) your tutorial page.

G.

-- 

**********************
http://www.oyonale.com
**********************
- Graphic experiments
- POV-Ray and Poser computer images
- Posters

Ross wrote:
> I just have to say that some aspects of your scene are mind boggling
> realistic. The water bottle looks totally real. The clock and the spices on
> top of the over... real. The drapes over the window, and the tiles are
> perfect.

   Thanks!

> really, the water bottle, even if just a mundane everyday object, stands out
> as being utterly real. fantastic work.

   Yes, it come out really good, perhaps because it is a double mesh 
"intruded" with Wings3D (the material is just Glass4, IIRC). But note 
how I carefully placed the orange to hide the ugly bottom part... :)

--
Jaime

Well, I just downloaded HDR Shop and upgraded my version of Poseray.
This HDRI stuff looked very challenging and time consuming when I was 
working on the contest entry. Now I have time to explore what it can do
for the next contest. 
Stay tuned :)

Chris Holtorf

"Chris Holtorf" <lho### [at] nwlinkcom> wrote in message 
news:1103_1108777138@news.povray.org...
> Well, I just downloaded HDR Shop and upgraded my version of Poseray.
> This HDRI stuff looked very challenging and time consuming when I was
> working on the contest entry. Now I have time to explore what it can do
> for the next contest.
> Stay tuned :)
>

The quick and easy method would be to simply download MegaPov 1.1, and then 
get the ready-made kitchen probe, 
http://www.debevec.org/Probes/kitchen_probe.hdr   That's neither challenging 
nor time-consuming; just the way I like things!  :-)

However, getting radiosity to look good in an HDRI scene can be challenging, 
in my experience.  But it's generally necessary in a picture in which you're 
likely to have recessed areas.

-- 
Jeremy
www.beantoad.com