I've been away from playing with Pov-Ray for a few years, so I haven't heard
about this utility. Some of the pictures I've seen in p.b.i. are stunning --
they look like photographs. I'm certainly not looking for advice on how to
use it (I'm back up to the point where I can make a scene with spheres and
boxes without screwing up :-) ), just a sort of basic explanation of what it
is, and how it works. Thanks.

Mark

Post a reply to this message

From what I know, it's an image which can have color channel values
greater than 1 (normal images can only have values between 0 and 1).
  That's it.

  The reason why that makes a big difference is another story, which I'm
not really qualified to explain, as I don't have any experience at all.

-- 
#macro N(D)#if(D>99)cylinder{M()#local D=div(D,104);M().5,2pigment{rgb M()}}
N(D)#end#end#macro M()<mod(D,13)-6mod(div(D,13)8)-3,10>#end blob{
N(11117333955)N(4254934330)N(3900569407)N(7382340)N(3358)N(970)}//  - Warp -

Post a reply to this message

In article <3e205225$1@news.povray.org>,
 "Mark Hanson" <mar### [at] attbicom> wrote:

> I've been away from playing with Pov-Ray for a few years, so I haven't heard
> about this utility. Some of the pictures I've seen in p.b.i. are stunning --
> they look like photographs. I'm certainly not looking for advice on how to
> use it (I'm back up to the point where I can make a scene with spheres and
> boxes without screwing up :-) ), just a sort of basic explanation of what it
> is, and how it works. Thanks.

Basically, to make a really realistic scene, it helps for your objects 
to have realistic surroundings and lighting, especially for things like 
reflections. You can construct this environment entirely in the 
computer, having the computer actually simulate the entire scene, but 
this takes memory, computation time, and is difficult or just time 
consuming.

HDRI means High Dynamic Range Image. Usually, image color values are 
percentages, you can have 0%, 100%, and steps in between. Of course, in 
reality, there is no "100% brightness", it is just a compromise for what 
our display devices can show. High dynamic range images store 
intensities instead of percentages, and can store values brighter than 
"white".

An HDRI image can be used to store lighting values for a scene, either 
precomputed ahead of time or taken from a real-world sample. Since the 
lighting values already exist, it doesn't take as long as having the 
actual scenery there, it is easier to set up, and the lighting is more 
realistic than a background from an ordinary image, with color values 
clipped to a small range.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/

Post a reply to this message

Very similar, in fact, to a convolution reverb, which samples the ambience
of a space and applies that to a sound recording, given the recording the
illusion of being in the space.
D.

"Christopher James Huff" <cja### [at] earthlinknet> wrote in message
news:cja### [at] netplexaussieorg...
> In article <3e205225$1@news.povray.org>,
>  "Mark Hanson" <mar### [at] attbicom> wrote:
>
> > I've been away from playing with Pov-Ray for a few years, so I haven't
heard
> > about this utility. Some of the pictures I've seen in p.b.i. are
stunning --
> > they look like photographs. I'm certainly not looking for advice on how
to
> > use it (I'm back up to the point where I can make a scene with spheres
and
> > boxes without screwing up :-) ), just a sort of basic explanation of
what it
> > is, and how it works. Thanks.
>
> Basically, to make a really realistic scene, it helps for your objects
> to have realistic surroundings and lighting, especially for things like
> reflections. You can construct this environment entirely in the
> computer, having the computer actually simulate the entire scene, but
> this takes memory, computation time, and is difficult or just time
> consuming.
>
> HDRI means High Dynamic Range Image. Usually, image color values are
> percentages, you can have 0%, 100%, and steps in between. Of course, in
> reality, there is no "100% brightness", it is just a compromise for what
> our display devices can show. High dynamic range images store
> intensities instead of percentages, and can store values brighter than
> "white".
>
> An HDRI image can be used to store lighting values for a scene, either
> precomputed ahead of time or taken from a real-world sample. Since the
> lighting values already exist, it doesn't take as long as having the
> actual scenery there, it is easier to set up, and the lighting is more
> realistic than a background from an ordinary image, with color values
> clipped to a small range.
>
> --
> Christopher James Huff <cja### [at] earthlinknet>
> http://home.earthlink.net/~cjameshuff/
> POV-Ray TAG: chr### [at] tagpovrayorg
> http://tag.povray.org/

Post a reply to this message

"Christopher James Huff" <cja### [at] earthlinknet> wrote in message
news:cja### [at] netplexaussieorg...
> An HDRI image can be used to store lighting values for a scene, either
> precomputed ahead of time or taken from a real-world sample. Since the
> lighting values already exist, it doesn't take as long as having the
> actual scenery there, it is easier to set up, and the lighting is more
> realistic than a background from an ordinary image, with color values
> clipped to a small range.

Where does the scene come from? A scene you've already rendered? From
reading a few of the posts in p.b.i., it seemed like they were photographs.
Is that it?

Mark

Post a reply to this message

In article <3e21b1b3$1@news.povray.org>,
 "Mark Hanson" <mar### [at] attbicom> wrote:

> "Christopher James Huff" <cja### [at] earthlinknet> wrote in message
> news:cja### [at] netplexaussieorg...
> > An HDRI image can be used to store lighting values for a scene, either
> > precomputed ahead of time or taken from a real-world sample. Since the
> > lighting values already exist, it doesn't take as long as having the
> > actual scenery there, it is easier to set up, and the lighting is more
> > realistic than a background from an ordinary image, with color values
> > clipped to a small range.
> 
> Where does the scene come from? A scene you've already rendered? From
> reading a few of the posts in p.b.i., it seemed like they were photographs.
> Is that it?

"either precomputed ahead of time or taken from a real-world sample."

It doesn't really matter where it originally came from...could be 
generated with a high-quality renderer, could be taken from a real-world 
location. If the patch allows POV to output images in that format, you 
could generate the images with POV. Then you would have to do the work 
of setting up the scenery, but you would only have to do that and render 
once, and could use the resulting HDRI map in several other scenes, or 
to make a faster rendering animation. Most HDRI maps seem to be 
real-world samples, probably because there isn't much rendering software 
that can output to those images. I think Radiance can do it, or it might 
just use its own RGBE format.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/

Post a reply to this message

You can look for "probes" at various sites that have been mentioned
recently.
D.

"Mark Hanson" <mar### [at] attbicom> wrote in message
news:3e21b1b3$1@news.povray.org...
> "Christopher James Huff" <cja### [at] earthlinknet> wrote in message
> news:cja### [at] netplexaussieorg...
> > An HDRI image can be used to store lighting values for a scene, either
> > precomputed ahead of time or taken from a real-world sample. Since the
> > lighting values already exist, it doesn't take as long as having the
> > actual scenery there, it is easier to set up, and the lighting is more
> > realistic than a background from an ordinary image, with color values
> > clipped to a small range.
>
> Where does the scene come from? A scene you've already rendered? From
> reading a few of the posts in p.b.i., it seemed like they were
photographs.
> Is that it?
>
> Mark
>
>

Post a reply to this message

What made HDRI make sense to me was the idea/fact that it was "invented" to
allow artificial 3D objects to be placed into a "real" scene.

Have you ever watched a program with CGI in an "real" scene where the CGI
just didn't look quite right, but you couldn't quite put your finger on why?
The likely cause was the improper lighting.  HDRI samples light differently
than, say, a single exposure on a digital camera.  From what I understand,
it does this by having multiple exposures of different lengths.  By doing
this, it can approximate the "real" intensity of the light.  By using this
light data, you can then place 3D objects into a "real" scene and have much
better lighting.

A good example is simply sunlight coming trough a window into a dark room.
On a normal photograph, the window may simply look "white".  However, having
a white piece of paper hanging on the wall does not begin to have the same
effect on lighting as sunlight coming through a window.  If you consider
all-white to be rgb<1,1,1>, then sunlight would be something like
rgb<1000,1000,1000>, but a normal digital photo can only show things in the
range rgb<0,0,0> to rgb<1,1,1>, so you'd lose all of that extra light.

I'm not sure if that made sense or not.  If you're like me, you'll be
driving down the road and suddenly go, "Hey, that makes sense now!"

Good Luck,

Slash

Post a reply to this message

"Slashdolt" <nomail@nomail> wrote in message
news:web.3e24683e552627465543301f0@news.povray.org...

<snip>

> I'm not sure if that made sense or not.  If you're like me, you'll be
> driving down the road and suddenly go, "Hey, that makes sense now!"

Well, I'm getting there. HDRI is a way of approximating real-life situations
that Pov-Ray can't do, or can't do well -- I'm thinking events like depth of
focus, glare, sun flares.

Next: is HDRI a program in itself?

Mark

Post a reply to this message

>
>Well, I'm getting there. HDRI is a way of approximating real-life situations
>that Pov-Ray can't do, or can't do well -- I'm thinking events like depth of
>focus, glare, sun flares.
>

Not quite.  It really has to do with one thing only, afaik.  Simply the
lighting.

By allowing some things to be brighter than simply "all-white" it allows you
to insert a 3D object into a "real life" photo, and have the same lighting
in the room as you did when the photo was taken.  To use my "sun coming
thru a window" analogy, your 3D object could actually be "lighted" from
where the sun hits on the far side of the room indirectly, and not just
from the actual light source.

I still don't feel I'm explaining this very well.  Maybe if I said something
like, "To some extent, it's like radiosity coming from a photograph rather
than from a light source bouncing off 3D objects in a completely rendered
scene."

Slash

Post a reply to this message

"Mark Hanson" <mar### [at] attbicom> a écrit dans le message de news:
3e2471fa$1@news.povray.org...

> Well, I'm getting there. HDRI is a way of approximating real-life
situations
> that Pov-Ray can't do, or can't do well -- I'm thinking events like depth
of
> focus, glare, sun flares.

No it's much simpler and limited in scope. Just think of it as a photograph
able to emit bright light. It doesn't add functionality to POV-Ray (it's
possible to have HDRI effects in POV-Ray without a patch), it's just that
HDRI photographs derived from natural environments give very realistic
results when used in 3D pics because they are by definition realistic
(realistic colors AND realistic light intensities). One thing that gives
away images using HDR maps is that the reflection of light sources is not
dimmed on poorly reflective objects (the reflection of a light bulb will be
bright even if the object has refection 0.3).

In fact, here is a basic HDR texture in regular POV-Ray:
texture{
    image_pattern{jpeg "areas_of_light_intensities"}
    texture_map{
        [0 pigment{color White} finish{ambient 0}] // regular White
        [1 pigment{color White} finish{ambient 1000}] // very very bright
White
    }
}

> Next: is HDRI a program in itself?

No, it's a way to store the light intensities with the color pixels. There
are several file formats available (HDR, PIC, TIFF adaptations seem the most
frequent). What MLPOv has is the support for the HDR format. There's a free
program called HDRShop that lets you create and view HDR image though.

G.

--

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

Post a reply to this message

Slashdolt wrote:
>>
>
>I still don't feel I'm explaining this very well.  Maybe if I said something
>like, "To some extent, it's like radiosity coming from a photograph rather
>than from a light source bouncing off 3D objects in a completely rendered
>scene."
>
>Slash
>

Well, I haven't tried it yet, so I may be completely wrong, but if I
understand what I've seen here, both in comments and in images, the HRDI
image IS the light source.  That requires an image with higher values than
1.

Best example I can think of is in my frozen moment IRTC entry
(http://www.irtc.org/ftp/pub/stills/2002-12-31/hang_rg.jpg) I use a
terragen image as a background. I also had to use a lightsource with a fade
power of about 10 to get the light on the foreground to look right, not to
mention the time I spent getting it positioned to look right.  If I had
used an HRDI image I wouldn't have had to add the light source, the HRDI
image would take care of that and it would be right where it belonged.

And that is pretty much what I understand its intended for. Unfortunately,
the patch came out about three days after I submitted it or I probably
would have tried it, since it looks like terragen supports this with a
plug-in... :)

RG

Post a reply to this message

"Slashdolt" <nomail@nomail> wrote in message
news:web.3e247766552627465543301f0@news.povray.org...
> >Well, I'm getting there. HDRI is a way of approximating real-life
situations
> >that Pov-Ray can't do, or can't do well -- I'm thinking events like depth
of
> >focus, glare, sun flares.
> >
>
> Not quite.  It really has to do with one thing only, afaik.  Simply the
> lighting.
>
> By allowing some things to be brighter than simply "all-white" it allows
you
> to insert a 3D object into a "real life" photo, and have the same lighting
> in the room as you did when the photo was taken.  To use my "sun coming
> thru a window" analogy, your 3D object could actually be "lighted" from
> where the sun hits on the far side of the room indirectly, and not just
> from the actual light source.
>
> I still don't feel I'm explaining this very well.

No, actually that about did it. I'm rendering a statue in a white room.
There is one light source illuminating the side of the statue the camera is
looking at, meaning the other side is dark. HDRI bounces the light off the
white walls and illuminates (partially) the other side if the statue. Do I
have it now? That's pretty cool.

Mark

Post a reply to this message

In article <3e24a4da@news.povray.org>,
 "Mark Hanson" <mar### [at] attbicom> wrote:

> No, actually that about did it. I'm rendering a statue in a white room.
> There is one light source illuminating the side of the statue the camera is
> looking at, meaning the other side is dark. HDRI bounces the light off the
> white walls and illuminates (partially) the other side if the statue. Do I
> have it now? That's pretty cool.

No. Radiosity alone does that. HDRI just lets you encode the lighting 
values in a high dynamic range image, so you don't have to calculate it 
during rendering and can use real-world surroundings without having to 
model them.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/

Post a reply to this message

"Christopher James Huff" <cja### [at] earthlinknet> wrote in message
news:cja### [at] netplexaussieorg...
> > No, actually that about did it. I'm rendering a statue in a white room.
> > There is one light source illuminating the side of the statue the camera
is
> > looking at, meaning the other side is dark. HDRI bounces the light off
the
> > white walls and illuminates (partially) the other side if the statue. Do
I
> > have it now? That's pretty cool.
>
> No. Radiosity alone does that. HDRI just lets you encode the lighting
> values in a high dynamic range image, so you don't have to calculate it
> during rendering and can use real-world surroundings without having to
> model them.

Okay, I give up. :-) I don't know enough about higher-end rendering to
understand it. But I'll get there some day. Thanks to everyone.

Mark

Post a reply to this message

> Okay, I give up. :-) I don't know enough about higher-end rendering to
> understand it. But I'll get there some day. Thanks to everyone.

Do not give up!

HDRI is just the BITMAP, nothing more.
Its higher dynamics & lower bounds on intensity clamping give you
opportunity to use it as a source of data which is more real than
clamped & more discretized RGB map such PNG,BMP etc.

Its a BITMAP!   ... used in a very cheap way to light the scene or
place more dynamic reflections/refractions.... its a touch of reality in
the very clamped POVRAY world....

Post a reply to this message

On Mon, 3 Mar 2003 15:07:05 +0100, "T.J.Viking" <vik### [at] bp-domarpl> wrote:
> its a touch of reality in
> the very clamped POVRAY world

would you like to make "clamped" word usage more clear here?

ABX

Post a reply to this message

> would you like to make "clamped" word usage more clear here?

clamping (in GFX world) - clipping some values in suitable range


.. in POVRAY clamping occurs in final RGB discretization process, but also is
present in radiosity code i many places - the author of implementation had some
intention to make POV radiosity more artistic one.. rather than real one....

Post a reply to this message

On Mon, 3 Mar 2003 15:46:50 +0100, "T.J.Viking" <vik### [at] bp-domarpl> wrote:
> .. in POVRAY clamping occurs in final RGB discretization process, but also is
> present in radiosity code i many places - the author of implementation had some
> intention to make POV radiosity more artistic one.. rather than real one....

Gooood. I was affraid that you meant "POV community" as "POV world" which could
change "clamped" sense a lot.

Have you done some "unclamping" for radiosity code ? Have you some results ? Any
patched version available ?

ABX

Post a reply to this message

"ABX" <abx### [at] abxartpl> wrote in message
news:85r66vgt97vbv62ou75qoimr6qv89ju5oe@4ax.com...
>
> Gooood. I was affraid that you meant "POV community" as "POV world" which
could
> change "clamped" sense a lot.
>

Now, *THATS* paranoid.... ;)

Post a reply to this message

> Gooood. I was affraid that you meant "POV community" as "POV world" which could
> change "clamped" sense a lot.

ehhhh :) no comment... :)
 
> Have you done some "unclamping" for radiosity code ? Have you some results ? Any
> patched version available ?

Nope.
I am writing my own GI renderer and studied radiosity/monte carlo/irradiance caching
over
years.... then tried to look how POV is doing that.

When I saw the GI code in POVRAY, I sat down and started to cry :)
Many bugs! Bugs meant by misunderstanding light theory and many nifty
"methods" of coping with "crossing 1's value".

I know the code is working, but is highly limited in some areas eg. light is not so
well
propagating in corridors, tunnels etc. due to many limits bound on GI values during
caching and mixing with diffuse coefficients - no matter how many GI bounces you
gave in rendering settings.

I think that it is the time to redesign radiosity code, there are so many new theories
and
algos now... somebody could boost POV in XXI century.

Post a reply to this message

"T.J.Viking" wrote:
> 
> [...]
> 
> I think that it is the time to redesign radiosity code, there are so many new
theories and
> algos now... somebody could boost POV in XXI century.

Very funny.

Instead of making 'wise' comments just get the POV-Ray source from

http://www.povray.org/download/

and implement a better radiosity function.  If you are as competent in
that matter as you pretend to be this should not be a problem.  If not i
suggest you either stop your complaints or support your critiques with
some proof.  This of course would require actually using POV-Ray.

Christoph

-- 
POV-Ray tutorials, include files, Sim-POV,
HCR-Edit and more: http://www.tu-bs.de/~y0013390/
Last updated 28 Feb. 2003 _____./\/^>_*_<^\/\.______

Post a reply to this message

"T.J.Viking" <vik### [at] bp-domarpl> wrote in message
news:3e646626$1@news.povray.org...

> I think that it is the time to redesign radiosity code, there are so many new
theories and
> algos now... somebody could boost POV in XXI century.

If you can provide a decent patch, I'm sure it will make it's way to megapov.
Once megapov gets enough features, it tends to become the standard
pov-executable for the majority of users.

Post a reply to this message

> > I think that it is the time to redesign radiosity code, there are so many new
theories and
> > algos now... somebody could boost POV in XXI century.
> Very funny.

Yup very funny indeed :)


> Instead of making 'wise' comments just get the POV-Ray source from

Being wise is not my mission...
 
> and implement a better radiosity function.  If you are as competent in
> that matter as you pretend to be this should not be a problem.  If not i
> suggest you either stop your complaints or support your critiques with
> some proof.  This of course would require actually using POV-Ray.

Yes I was, I am & I will (I hope) use POV :)
Your problems are not my problems, I can live with it how POV is working.

I do not understand one thing, why POV community is so touchy about any
complaints..... POV is marvelous, but as everything on the world can be better.

And one word to you guys..... go for a walk, and leave POV for a while... you are
going crazy
about you "preccious"

Post a reply to this message

"T.J.Viking" wrote:
> 
> [...]
> Your problems are not my problems [...]
> 
> I do not understand one thing, why POV community is so touchy about any
                                         ^^^^^^^^^
> complaints..... 

You gave the reason yourself.  Because it is a community.  Just making
complaints without supporting them with actual arguments and proofs is not
of any help.  Do you really think people actually using POV-Ray everyday
can't complain about its shortcomings themselves?  What you said clearly
places you outside the community.

I strongly suggest you reread my last post because following its
suggestions will almost surely guarantee you friendly replies to your
postings.  

Christoph

-- 
POV-Ray tutorials, include files, Sim-POV,
HCR-Edit and more: http://www.tu-bs.de/~y0013390/
Last updated 28 Feb. 2003 _____./\/^>_*_<^\/\.______

Post a reply to this message

> You gave the reason yourself.  Because it is a community.  Just making
> complaints without supporting them with actual arguments and proofs is not
> of any help.  Do you really think people actually using POV-Ray everyday
> can't complain about its shortcomings themselves?  What you said clearly
> places you outside the community.

I really appreciate what youve done to the community Chris,
but you simply not understanded my intentions...

My intention was to start talking about changes to the radiosity code.
Do not put that heavy work to one and only person... its undoable in
the current state of code - in my opinion most of the features rely on
structures used not only in radiosity code...
 
> I strongly suggest you reread my last post because following its
> suggestions will almost surely guarantee you friendly replies to your
> postings.  

Your suggest leads to nowhere...
Many people was using GI in POV for years and know their problems better
than me and you. Let them speak about it if you even matter about "community".
It is not communism it is more like democracy - let other people have their
opinions and needs.

The matter is open... let the people speak, then start implementing.

Post a reply to this message

On Tue, 4 Mar 2003 09:38:24 +0100, "T.J.Viking" <vik### [at] bp-domarpl> wrote:
> > Gooood. I was affraid that you meant "POV community" as "POV world" which could
> > change "clamped" sense a lot.
>
> ehhhh :) no comment... :)

Sorry. Your CV at http://news.povray.org/search/advanced/?s=Viking&a=1 is short
so I wasn't sure your intentions. The meaning of some recent threads made me sad
and I become sensitive.

> > Have you done some "unclamping" for radiosity code ? Have you some results ? Any
> > patched version available ?
>
> Nope.
> I am writing my own GI renderer and studied radiosity/monte carlo/irradiance caching
over
> years.... then tried to look how POV is doing that.
>
> When I saw the GI code in POVRAY, I sat down and started to cry :)
> Many bugs! Bugs meant by misunderstanding light theory and many nifty
> "methods" of coping with "crossing 1's value".

Can you refer to exact line in sources? Knowing what is broken can allow make it
better. Having more info MegaPOV can make those bugs "optional". Can you share
your knowledge and help us make it better ?

> I think that it is the time to redesign radiosity code, there are so many new
theories and
> algos now... somebody could boost POV in XXI century.

Tomku, zarówno zródla POV-Raya jak i MegaPOV sa publiczne, z checia
przetestujemy twoje propozycje. Zachecam do wypuszczenia patcha. Jesli tylko
jestes chetny do wspólpracy zapraszam do kontaktu ze mna: abx### [at] abxartpl :-)

ABX

Post a reply to this message

> Can you refer to exact line in sources? Knowing what is broken can allow make it
> better. Having more info MegaPOV can make those bugs "optional". Can you share
> your knowledge and help us make it better ?

Yes I will provide full list of "bad points" in code.
Where should I post it ? Which group would be the best for such discussion?

Post a reply to this message

On Tue, 4 Mar 2003 10:39:13 +0100, "T.J.Viking" <vik### [at] bp-domarpl> wrote:
> Your problems are not my problems, I can live with it how POV is working.

Wait, Tomek!

Did you said you have read the sources ? Did you said you have seen bugs there ?
Do you want to be parasite only ? We (community) give you application,
resources, contests, nearly on-line help. Please give us something too. POV-Ray
wasn't created in one week. Everyone bring something to it during last eleven
years. Having your post we have signal something is wrong. Writing what
*exactly* is wrong you can make time of repair short. Just complaining you did
not help us at all and we are still at the same place with the same real life
burdens and own current tasks opened.

ABX

Post a reply to this message

On Tue, 4 Mar 2003 12:25:08 +0100, "T.J.Viking" <vik### [at] bp-domarpl> wrote:
> Yes I will provide full list of "bad points" in code.
> Where should I post it ? Which group would be the best for such discussion?

I think:
- The povray.programming for current source code discussions.
- The povray.unofficial.patches for complete working changes.
- The povray.binaries.utilities for uploading files.

http://www.povray.org/resources/newsgroups/


ABX

Post a reply to this message

On Tue, 4 Mar 2003 10:39:13 +0100, "T.J.Viking" <vik### [at] bp-domarpl>
wrote:

>And one word to you guys..... go for a walk, and leave POV for a while... you are
going crazy
>about you "preccious"

I can assert that Chris *does* go for a walk from time to time, even
if only to meet fellow POVers or ride his insane home-made bike :)


Peter Popov ICQ : 15002700
Personal e-mail : pet### [at] vipbg
TAG      e-mail : pet### [at] tagpovrayorg

Post a reply to this message

"T.J.Viking" <vik### [at] bp-domarpl> wrote in message
news:3e6361af@news.povray.org...
> > Okay, I give up. :-) I don't know enough about higher-end rendering to
> > understand it. But I'll get there some day. Thanks to everyone.
>
> Do not give up!
>
> HDRI is just the BITMAP, nothing more.
> Its higher dynamics & lower bounds on intensity clamping give you
> opportunity to use it as a source of data which is more real than
> clamped & more discretized RGB map such PNG,BMP etc.

I'm mildly flattered that you imagine that I could understand that.

Mark

Post a reply to this message

In article <3e6e63ac$1@news.povray.org>,
 "Mark Hanson" <mar### [at] attbicom> wrote:

> > HDRI is just the BITMAP, nothing more.
> > Its higher dynamics & lower bounds on intensity clamping give you
> > opportunity to use it as a source of data which is more real than
> > clamped & more discretized RGB map such PNG,BMP etc.
> 
> I'm mildly flattered that you imagine that I could understand that.

Ordinary images store intensity percentages. You can have from 0% to 
100% intensity, with 100% being "white", anything brighter gets chopped 
off. HDRI doesn't have that limitation, it keeps more information which 
makes it useful in processing and rendering calculations even if it 
can't be displayed.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/

Post a reply to this message