#3DSV3 raytracing
36 messages in this thread
I have just read the upgrade list for 3DS, and I am looking foward to the
switch. I have one question, though. Does V3 use ray tracing to handle
refections off of flat surfaces? This is crucial to a class of problems we need
to solve, since we use 3DS to determine what a camera in an instrumentation
package will see in test setup, and we often use mirros as part of our optical
configuration. We have found that the way V2.x works, which takes a bitmap
rendering adn overlays it on a reflecting surface, is not good enough for most
of what we do with mirrors. Thanks for your time Rich Schwartz
Rich, R3 uses ray-tracing as an optional way of computing shadows only… not
reflections.
– G
Gary:
The R3 new ray-traced light source seems just to be the SUN I missed so many
times! Does it really mean we'll see a parallel light source, determined it's
direction by a simple vector for the whole scene? Furthermore: Is there already
a kind of 'sun-dialog' regarding location, date, time? (Sun-IPAS-Greg is
listening….. I can feel it)
Thanks for your answer! …………………..Alexander.
Alex:
>> Is there already a kind of 'sun-dialog' regarding location, date, time?
>> (Sun-IPAS-Greg is listening….. I can feel it)
Yes, I am listening! No, it is not built in, you should still use ours to
both locate and animate the Sun in Release 2 or Release 3! <g>
Greg Pyros
Hi Greg:
>> Yes, I am listening!
I knew it! I'll find out whether your IPAS is the $1.00 difference worth
regarding the Schreiber offer…. <g>
I'll fax you an order. Please tell me total cost over the sea. Do you accept
Mastercard?
Alex. MATHYS – AGV Fax: 011-411-302-3727
Alex:
>> I'll find out whether your [SunPath] IPAS is the $1.00 difference worth
>> regarding the Schreiber offer…
I'd never put down a competitor, (well, almost never <g>), especially since
we sell their other excellent products also, but ours is the only Sun
routine that works totally inside 3D Studio as an IPAS routine!
The _other_ one requires you to save your mesh, exit 3DS, run the program,
re-start 3DS, and then load the mesh again! Should be worth the $1.00
difference in price the first time you use it on a large model! <g>
Greg (IPAS-R-Us) Pyros
Greg,
Actually they don't have to leave 3DS completely for Schreiber's Sun routine.
Granted it is not an IPAS because of the issue of Spot light creation. To
avoid quitting 3DS, they can save the .3DS file, Shell to dos and run the sun
routine, exit back into 3DS and then simply reload the modified .3DS file. Not
too much of a penalty when shelling, but it does require a reload of the file.
Trade off is that they end up with an optimized spotlight for nearly parallel
shadows and optionally an object representing the sun itself. Both the sun
object and the spotlight have the keyframe data established when they reload
the .3DS file. Maybe with the new IPAS3 features, guys like Keith and Gus can
give us some really cool tools.
CT.
Chris:
>> [Schreiber's Sun routine] To avoid quitting 3DS, they can save the .3DS
>> file, Shell to dos and run the sun routine, exit back into 3DS and then
>> simply reload the modified .3DS file. Not too much of a penalty when
>> shelling, but it does require a reload of the file.
Aha! Thanks for the clarification! That is a bit better than I was told!
>> optionally an object representing the sun itself.
Our IPAS routine can insert and animate an object and/or a light for the
Sun, also the moon (moonlight studies <g>), or any other planet in our solar
system! Great for those times when you need to verify the influence Neptune
will have on your new skyscraper!
Greg Pyros
Greg,
Does your Sunpath IPAS control the light (spotlight?) entirely, or is
there some setup required in 3DS?
Don Hanson
Greg:
Thanks for the $1.00 difference details….
Fax's coming.
Alex.
As Greg said, he sells an IPAS routine that sets the sun position, and the
Schreiber Instruments folks have an additional method of doing that. We didn't
want to ruin all the hard work they put into their add-ons, so it's not built
into R3.
– G
Gary:
Thanks for your answer. I've seen Greg's IPAS routine…. looks like the way to
go. Could you tell me a word more about the '…new ray-traced light
source…simulating a shadow-casting sun in any size scene…' ? Does this mean
that there will be a new sort of shadow with improved quality for 'long
distance spots'?
Thanks for your reply.
Alex.
Hi Alexander,
Gary is quite busy right now catching up on post-Siggraph stuff, so just let me
jump in here with a couple of things:
From what I saw at Siggraph, the ray-tracing spotlights are VERY accurate with
sharp, clean lines and very high detail. Unfortunately, because ray-tracing is
involved, they can slow rendering speed down considerably when influenced by
large amounts of geometry. Great for high-res, detailed stills, or animations
with little geometry that need VERY accurate shadows. Spolight Overshoot, on
the other hand, may be just what you are looking for. It will concentrate
shadow-mapping ONLY within the falloff cone while lighting the rest of the
scene with an even, bright light. This way you may use a MUCH smaller size
shadow map for the important parts of a large scene, get nice shadows, and the
rest of the scene will be "bathed" in light, although not completely parallel
(depending on the cone angle).
I'm sure Gary will add anything I may have left out…
-Alan Iglesias
Alan:
It appears to me that the rendering speed increase of 3.0 is just about
balanced by the slowdown required for the ray traced spotlights… and it also
appears to me that all architectural modelers will want to use the ray traced
spotlights for exterior shots. Note that this is a very preliminary observation
on my part.
C#
Note that Alan's comment about using the spotlight overshoot option instead of
ray-traced shadows is very appropriate. It means that architects can (in many
many cases) get away with still using shadow-mapped lights using the overshoot
function — and not have to resort to ray-tracing the shadows.
Spotlight overshoot is extremely powerful AND gives you the ability to soften
your shadows a bit.
– G
G:
Yes, I agree… but I don't like soft shadows in presentation output (still
rendering is the only place I would use ray traced shadows…). The contrast is
important to the presentation. I also didn't mean to sound like I was
criticizing. The difference between 2.0 and 3.0 looks pretty amazing to me!
C#
Hi Graig,
Um, actually from what I've seen, the ray-traced spotlights will probably only
be used on a very specific basis, so I wouldn't characterize them as really
"slowing down" the renderer on a general basis. When you consider the speed is
quite a bit faster than r2 on AA/High and the quality is WAY better, this is
where the speed-up is evident. Although I haven't done a ton of architectural
stuff, I would theorize that in many cases, the Spotlight Overshoot function is
gonna be a very viable option, especially for animations. When you REALLY need
absolutely perfect, sharp shadows (mostly for stills, I'd guess), the ray-trace
function will be a great tool to have. The bottom line is this: Everyone now
has MANY more lighting options with which to tailor their scene in the way that
best applies to their job at hand — a true hallmark of an exteremely versatile
production renderer!
-Alan
Alan:
Yep… what I just said to G. There is a DEFINITE improvement in the product
for use in architectural modeling. I can't wait to have alot of free time and a
decent design to work with… plus some new hardware. Anybody got an idea for
creating a winning Lotto ticket in 3DS?
C#
Hi Alan:
Thanks much for your details on the new r3 shadow possibilities. It really
looks like they'll fit my needs – I do mainly architectural stills. The map
sizes I have to use today to do far away narrow spots a really big. So, looking
forward to r3! …..not only because of the shadows, but the new lighting
possibilities in general – including 'negativ' light, also adjustable self
illuminating,…..!
Thanks again……… Alex.
Hi Alexander,
Yep, it certainly seems like we've got about a TON of lighting possibilities
coming up — truly exciting stuff! Should be no problem finding the perfect
combination for a particular scene once familiar with all the options…
-Alan
PMJI, but I used to work doing lighting for movies and tv shows and the like. I
remember the first time I worked on a really big movie with a ten ton lighting
package – that's a package that fits into an eighteen wheeler semi (LOTS of
lights!!!). Coming from little one ton packages on low budget commercials, I
was really confuzeled when I stepped into the truck and looked at the legions
of inkies, tweenies, mickey moles, silver bullets, etc… staring me in the
face, asking "what next?". That's probably how I'll feel the first couple of
days (make that weeks) with R3 <g>. I can't wait!
John Tissavary (La Luna cie)
John – Are there any reference materials, that you're aware of, worth their
salt in discussing stage lighting? As a former light person, is on the job
training the only way to grasp the basics/essentials?
David Taffet
The classic tome on stage lighting (which may still be in print, but I'm not
sure) is "A Method for Lighting the Stage" By Stanley McCandless.
– G
Gary's reply is quite relevant. I think it's IATSE local 16 apprentices'
required reading for stagehand journeymanship qualification, but I'm not sure
because I came into that local from another one where there was no stage
jurisdiction.
As far as basics are concerned, I'm sure there are several books out there,
probably available at Samuel French's bookstore in LA, and I believe it is
possible to understand the basics from reading a book. Putting basics to
practical use is, of course, the skill and art of an experienced lighting
person.
I did mostly film lighting and really did learn almost everything on the job.
In addition to the basic premises of lighting, which can be learned from text,
the tricks and variations required for practical production are so numerous and
ephemeral that there's no book in the world that could include them all. From
my experience, and seeing others work, most of them are made up on the spot.
Hope your as confused as I am,
John Tissavary (La Luna cie)
Hi John,
It was nice meeting your father and yourself up in Anaheim — Maybe we'll meet
again next year. I hope you both had a nice time in SoCal.
Sounds like quite a light-job you had! I guess the term "tons" of lighting
stuff was especially appropriate for you back then<g>. You probably *could*
spend a lot of time getting familiar with r3's new lighting stuff. I can't WAIT
to see the tutorial!
-Alan
We did have a nice, although sometimes stressful time. It's amazing how much
techno junk can be crammed onto a convention center, and how much stimulus one
brain can handle in one day.
I'm sure I'll see you at Siggraph next year, and am looking forward to it.
And I'm also looking forward to seeing how the Yost group tackles the problem
of creating manuals for R3. I don't envy that job!
John Tissavary (La Luna cie)
Alexander,
the light source does not use parallel rays. It's still based on a spotlight,
so the best you could get would be 1 degree hotspot, 1.5 degree falloff. That
should be good enough in most circumstances, however.
Hi Martin:
Thanks for your answer. Huhhhh I'm a bit disappointed…. other programs seem
to manage well parallel lights. Thanks for the 'degrees'! Regarding the other
shadow parameters of distant spots, what would you suggest? It looks like a
bias of 0.7 and sample range of ca. 5 gives me good results, including a
terrible big map size (1200 and up).
Alex.
Alexander,
I used a small bias of 0.1 or 0.2, samples =7, and map size of around 1200,
when I did a lot of architectural. Remember those are world units and therefore
the size of the geometry will effect the results. The new ray traced shadows
use only bias it seems, no map size or samples.
Martin:
>> …when I did a lot of architectural…
difficult clients over here… I'm one of them too <g>. To what other areas did
you move after the architects ?
>> … no map size or samples.
This sounds _really_ good.
Thanks again for information ………….. Alex.
Alexander,
>> To what other areas did you move after the architects ?
Mostly projects in the "entertainment" industry. Things like games (Sega
cd-rom); animations for niteclubs, restaurants, and theme parks (Universal
Studios, Warner Brothers); and, pre-visualization of movie stunt, fight scenes,
or special effects (Sony Pictures: Tristar's "Wolf" and Columbia's "My life").
There is more work in those kind of things than for architecture around here
(L.A.). When an architectural project does happen, though, it is often quite
big needing a whole team of people. There's just not enough of those kind of
projects to live off at the moment – wie eine Schade, nicht?
Martin
Actually, if you move the light source far enough away from your scene, you can
get parallel ray effects. It's really no problem at all.
– G
Alexander,
Schreiber Instruments has an Imagine Sun IPAS ($99) which inserts a
light and scaled, colored mesh object representing the sun at the requested
keyframes. The sun is placed as close as possible to the the model to keep the
light very nearly parallel (approx. 1 degree). The sun is enlarged and
reddened at sunrise and sunset. Schreiber sells through dealers such as
myself.
Kevin Krell – Computer Support Associates
Kevin:
Thanks for the quick answer. I've seen Greg's IPAS routine – but didn't know
about Schreiber's before (I use their trees for stills…. and for hard
hardware testings <g>).
Thanks again.
Alex.
Gary-
I don't know when we're going to get info like this, but I would assume that
the ray is traced from the viewposition to the point on the near face at each
pixel, and then to each light source?
Seems like this process might be time-consuming, but wouldn't take up any more
memory?
–Noah
Correct, Noah… and it usually takes much less memory than using a large
shadow map.
– G