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Jeet
11-27-2005, 10:42 AM
Dear friends,

I am using hdri for my scene in c4d. Now I am using GI to lighting my scene...Image is attached.

Now i want to add some caustic effect in the scene... can i get caustics without adding another light source to the scene?

regards

jeet.

tcastudios
11-27-2005, 10:55 AM
You do need a light source to create caustics, but it can be an "inviseble" light.
Turn all light emitting parameters of and enable the caustic settings.

Cheers
Lennart

Jeet
11-27-2005, 12:54 PM
You do need a light source to create caustics, but it can be an "inviseble" light.
Turn all light emitting parameters of and enable the caustic settings.

Cheers
Lennart

Thankyou friend... i tried the setting before but due to less energy i didnt see the result.. but i tried again and it helped me... now its working perfectly...

A big Thankyou ... not to say just the thanks... But For what you have really helped for...

I will allways remember lennart has helped me.

REgards

Jeet.

DynamicRealism
11-27-2005, 06:38 PM
this is possible with fr2

Jeet
11-28-2005, 02:13 AM
Sorry friend...


I am not having FR2... but glad to know that such provision is there...

I think you are using FR2... what do you think? which is better AR2 or FR2?

oh... did i asked hard question?

I just want to know for my curiosity... no fighting with rendering engines...

regards

jeet.

DynamicRealism
11-28-2005, 03:02 AM
i hope no one takes offense to this, but my honesty says that im disgraced to have AR in cinema. I will never go back to it having fr2, never in a million years. Thats only my 2 cents.

Per-Anders
11-28-2005, 04:25 AM
Guys just a note please keep it civil. DynamicRealism, I'm glad you like the engine, but maybe reduce the fanboy quotent a little.

Now in answer to the original question. Both engines are good. fR is currently in my oppinion better. For production ready GI I don't think you'll find a faster or better engine on the market than Final Render stage 2 currently (and yes that includes VRay in my oppinion, though we'll see come the next update of VRay), and fR certainly has vastly superior DOF and Moblur to AR (and much faster). fR also has greater flexibility within the materials system with the ability to use Cinema's own standard material and many of it's shaders as well as a fully featured node based Texture Tree. AR does however have some areas where it still outshines fR, namely in the lighting. AR area lights are much more flexible and controllable than those in fR, additionally AR's shadowmaps produce both smoother maps and are deep shadow maps (they handle colored layered transparency and materials etc) which fR's currently dont.

AdamT
11-28-2005, 04:39 AM
I may be mistaken, but I don't think that fR is able to generate caustics from GI lighting. It can take caustics into acount in the GI calculation, but GI itself can't create caustics.

Maxwell is the only engine I know that can create GI caustics, but there may be others.

Per-Anders
11-28-2005, 05:04 AM
actually fR does do GI caustics, you can try this experiment to see.

make a basic reflective torus, a disc obejct and a cube

move the torus slightly above the disc and stretch it vertically to make a ring

make the disc really big so that it makes a nice "ground"

apply a luminant material to the cube, and set it's brightness to say 200%, then position it where you want a lightsource to be

in the render settings turn off Autolight so that the only light source will be the luminous cube.

in fr turn on gi and turn on "Consider GI caustics", and set the gi multiplier to 10.

hit render, and you should see (softly though unless your'e using montecarlo or a high resolution) the caustics pattern from the cube lightsource.


in actually fact any photon based gi solution should be able to support gi caustics, only AR doesn't. however interestingly even fR's montecarlo mode supports GI based caustics.

Per-Anders
11-28-2005, 05:33 AM
just to proove that it fr does support hdri generated caustics, this image is lit only with the kitchen hdri scene (set to 150% brightness to enhance the caustics effect).

http://www.peranders.com/general/frhdrigi.jpg

by the way if you want to get caustics with an hdri in AR though you could try using DiTools to clone a light over a form, and use the forms texture to control the lights color and where the lights are placed, this will take longer, but you can get some ok effects this way for sure.

DynamicRealism
11-28-2005, 05:36 AM
I may be mistaken, but I don't think that fR is able to generate caustics from GI lighting. It can take caustics into acount in the GI calculation, but GI itself can't create caustics.

Maxwell is the only engine I know that can create GI caustics, but there may be others.


=)

http://members.cox.net/dbxs/caustics.jpg

DynamicRealism
11-28-2005, 05:38 AM
cool ring btw mdme !

AdamT
11-28-2005, 05:41 AM
actually fR does do GI caustics, you can try this experiment to see.

That's good to know, but my main point is that fR won't generate caustics from secondary sources, e.g., from indirect light. Maxwell can do that.

Per-Anders
11-28-2005, 05:48 AM
um, i'm not sure i follow you, there are two examples that show it is producing caustics from indirect light sources. there was no light source in my scene, only and HDRI texture on a sky object.

the caustics are begin generated by the GI solution, not by direct light sources, you could use any obejct for this, and any bounces will also create their own caustics.

AdamT
11-28-2005, 05:51 AM
I can tell from the pics but I suspect your HDRI is a direct light source. By indirect I mean bounced light.

AdamT
11-28-2005, 05:53 AM
And never mind, I stand corrected! I was experimenting with a glass object and I guess the caustic was too subtle to show up. I just tried again with a ring and it absolutely works. Thanks!

Per-Anders
11-28-2005, 06:08 AM
no, there's no "direct" light source apart from real lights with GI. with radiosity it's another matter, but gi is backwards traced so every part of gi is secondary bounce. i'll show you an example to proove that all gi caustics are bounce caustics (ogviously the more bounced you have the harder it is to show as the bounce becomes more indistinct and overidden by the brighter earlier bounces).

in this scene there are two vertical blocks as you can see. on the far left hidden by the left block is a light, the left block cases the ring in this scene in total shadow, but the light is just high enough to illuminate the block on the right. thus the only light the ring recieves is bounced light.

the light doesn't have "caustics" enabled.

the block surface are matte white.

in this image you can see how it looks with 3 bounces and "Consider GI Caustics" turned off

http://www.peranders.com/general/frbouncenocaustics.jpg

in this image you can see how it looks with 3 bounces and "Consider GI Caustics" turned on.

http://www.peranders.com/general/frbouncewithcaustics.jpg

as you can see secondary bounces produce caustics just the same (obviously a more diffuse caustic as it's not such a focused light source).

marcom
11-28-2005, 06:17 AM
just a quick question mdme-sadie:
those pix are done in fr, right?

(i'm getting slowly drawn to this render engine, must.resist.budget.spent.for.xmas...)

cheers
marcom

Per-Anders
11-28-2005, 06:55 AM
hi, yes, those are fR pics.

lllab
11-28-2005, 08:19 AM
well i must say FR GI comes very close to maxwell, although for sure it is not a physical simulator for sure.

i am very happy to own both- FR2 has a great amount of adjustment and highly optimized GI and raytracing, MW is inj fact a physical simulation, great for fast setups, maybe longer rendertimes where you want to be close to reality (not always wanted).

ciustics from GI bounces-thats great and shows the power of FR:-)

cheers
stefan

Chrissyboy
11-28-2005, 10:00 AM
in this image you can see how it looks with 3 bounces and "Consider GI Caustics" turned off
...
in this image you can see how it looks with 3 bounces and "Consider GI Caustics" turned on.
...

This is great, an unexpected bonus to be honest. Can I ask how this affected render times? I don't mean to the second, just an idea if it enabling GI caustics doubled the time, trebled it, etc in this instance.

Wonder how that Mac version is coming on...

C

AdamT
11-28-2005, 02:41 PM
well i must say FR GI comes very close to maxwell, although for sure it is not a physical simulator for sure.

i am very happy to own both- FR2 has a great amount of adjustment and highly optimized GI and raytracing, MW is inj fact a physical simulation, great for fast setups, maybe longer rendertimes where you want to be close to reality (not always wanted).

ciustics from GI bounces-thats great and shows the power of FR:-)

cheers
stefan
I couldn't agree more, and thanks again for the cool fR-2 examples.

In my own defense, I was led astray by the fR-2 manual's very brief description of GI caustics:

"Consider GI-Caustics - when turned on, caustic rendering effects will add to the GI solution. This can be used to illuminate the surrounding of a caustic light pattern."

Which I interpretted to mean that the light from the caustic pattern would brighten surrounding areas if the switch was enabled. Obviously, as you point out, it means a lot more than that!

Jeet
11-28-2005, 06:00 PM
Hi friends,

I was not knowing, the thread started by me has so many replies.. may be i didnt get the notification of the replies comming... anyways... I am just a beginner...

Well, i think in AR... they have put caustic and GI effect different because they want us to control more over Caustics...

Yesterday i was playing to find how i could be able to get the caustics with GI... and i found one method..

In that, we can use GI settings globaly + need to add one light for caustics and it will have diffuse and specular option OFF....

That way, only emmited photon will create the caustics... seems easy and more controlling of a kind.

Attached image is rendered in maxwell by thomas... definately in maxwell... but we can see GI+ caustics... dont know which setup of light he has used... But really impressive rendering... I remember it took about 35-38 hours on some good configuration pc.

Best Regards

Jeet.

Jeet
11-28-2005, 06:39 PM
I may be mistaken, but I don't think that fR is able to generate caustics from GI lighting. It can take caustics into acount in the GI calculation, but GI itself can't create caustics.

Maxwell is the only engine I know that can create GI caustics, but there may be others.

Dear Adam and mdme_sadie,

Well, reading some last threads i can see that fR is really able to generate the caustics with GI... And no doubt about maxwell... it can generate the caustics too...

+++ In addition let me remind that... without GI, caustics can be generated with a single light source... so the same way... with GI and hdri one can generate Caustics too... That too with AR2.5... without using external light source and or plugin... But what you need is hdri that contain a very sharp light source like the sun... I have used sky presets available in cinema 4d 9.5.... This sun will work as a light source... that will emmit photons with more energy compare to the sky... there by it will produce the same caustics like a omni light can produce... but what we can see is the addition effect of light+sky...

And i beleive its true caustics only...

Example is attached. The scene contain one ring, floor and sky. And GI is enable ...settings are below...

Strenght 150
Accuracy 70
Diffuse path 1
Stoch.. samples 300
Resolution 50-80

Cheers

Jeet.

AdamT
11-28-2005, 07:35 PM
Not exactly sure what you're saying, but there's clearly light being used in that thumbnail you posted. I think the Sky plugin uses an infinite light to represent sunlight.

Jeet
11-29-2005, 03:59 AM
Not exactly sure what you're saying, but there's clearly light being used in that thumbnail you posted. I think the Sky plugin uses an infinite light to represent sunlight.

Dear AdamT,

I have not used a single light sournce... I have used a sky... that is working as an hdri... I can send you scene file if you want...may be you want to say is... they have programmed an infinite lightsource for the sun...

I thinkyou can still achieve the same thing if you have such an hdri that contain sun... yes... a real hdri but with sun.

Regards

Jeet.

Per-Anders
11-29-2005, 04:17 AM
"Sky" isn't just an image, it's the sky object itself it's textures, and a combo of a general area light and a sun light, these are normal lights that emit caustics and all the rest. If you want to see what a the Sky plugin Sky is made up of then make a new one, and hit current state to object, you'll see that it contains, the sky, a sky dome area light, a sin light and a moon light. They're not image based, sorry.

AdamT
11-29-2005, 04:19 AM
I thinkyou can still achieve the same thing if you have such an hdri that contain sun... yes... a real hdri but with sun.
Sorry, but you just can't. Wish you could, but you can't.

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