Object as lights?

[crazy homeless guy]

I have a question about the best method to generate cove lighting. In the past I have done this be creating an object the shape I want, and then assigning it a shader that casts light. This is then naturally the direction I want to take with Mental Ray, but Mental Ray does not seem to work well in this way. Or at least using the method I am trying, maybe I am missing something.

Right now I am using a A&D shader with self illumination enabled. I then have the self illumination set to interact with the final gather solution. It does illuminate, but the problem is that a lot of splotchiness and samples are clearly visible in the image that renders. I have the FG settings set reasonable high, and I have the interpolation set to about 80. I don't want to go higher than that, because I don't want to loose anymore detail in the image than I have too. I could probably go to about 300-400 and smooth these out, but that is going to flatten the entire image, and make it look muddy.

I thought I could use the ctrl_objectlights shader, and make the object generate photons that contribute to the scene, but that shader is not compiled for Max2009 64bit. Or at least I could not find it compiled for this release. I searched around for other shaders, but have not really turned anything up.

So, ....I am curious what are others using to work through this? Does anyone have better ways than I am trying? I am using Max2009, I won't be able to flip to 2010 for at least another month. Does 2010. MR 3.7.5 handle it better than 3.6.5?

I have done cove's some what successfully using a linear area and an IES file, but would like an easier way than positioning all of those individual lights.

[banned]

That is very big Problem, autodesk must fix it.

Mental images have inlcude the objet-light shader in the production.dll at Version 3.65, but it gives not a MI-File and Autodesk must include the technology, because the Lights-System from 3dsmax are not compatible with Object_Light from mental ray. I have ask mental images for the MI-File or definition of the object_light Shader, but no answer.

[Seeda]

That also interests me too, i have the same problem as Crazy homeless guy, an object light based Shader would be the best solution, perhaps we should write a petition to MI , to get this MI file.

[jetBlack]

I would definitely sign that !!

[crazy homeless guy]

Mental images have inlcude the objet-light shader in the production.dll at Version 3.65, but it gives not a MI-File and Autodesk must include the technology, because the Lights-System from 3dsmax are not compatible with Object_Light from mental ray. I have ask mental images for the MI-File or definition of the object_light Shader, but no answer.

Is there any difference in version 3.7.5 that shipped with Max2010?

-----

I guess it is good to know that I am not doing something obviously wrong, and it is a problem everyone is having. I haven't tried to render a production scene with Irradiance Particles yet, but perhaps this could be the first. Maybe that will provide a smoother solution from an object based light. This would be the perfect project to start putting them into production since it is a series of product style shots of airport desk and kiosk configurations.

[Wobi]

hot chip wrote:

Mental images have inlcude the objet-light shader in the production.dll at Version 3.65, but it gives not a MI-File and Autodesk must include the technology, because the Lights-System from 3dsmax are not compatible with Object_Light from mental ray. I have ask mental images for the MI-File or definition of the object_light Shader, but no answer.

Hmm, I think this isn't quite right. Mental Ray itself has the opportunity to use objects as lights, but unfortunately they have not written a light shader for that feature. Didn't ever hear about that a "new" light shader resists inside the production.dll??? Where did you get that information from hot chip? I'm quite sure that this isn't right, but maybe I'm totally wrong

So you would have to write such a shader yourself which is just impossible for 99,9% of mental ray users. The only existing shader I know for this purpose is the geolight-Shader from ctrl. But there isn't a 64-Bit-Version of it and it seems as if the shader is quite in a beta stage till now. Also I havent heard of any updates in the last time...
So, conclusion is that mental ray itself has the ability for real object light but its quite impossible to make use of it... especially in 3ds max... But you might give the geolight shader a try

EDIT: Maybe hot chip is speaking of the light_surface shader... but thats not a light shader but a material shader... hmm...

[banned]

hi

i mean object_light from a mesh. This information is from Steffen Römer /mental images and he have say it on the mental ray workshop in Berlin. All participants can confirm this.

mfg
hot chip

[crazy homeless guy]

While far from perfect, I may be able to work around the problem for now by applying a FG multiplier at the material level. Of course this will slow down calculations of the image, but this project consists of small files, so it may work for now.

I am lighting the inside of a box with another box as a test. Ignore the light on the side of the box, I did this test inside of another scene, so that light is left over.

The first image has the FG set to medium with the preset slider. Splotchy inside as expected. If I increase the box FG multiplier to 5, it smooths out quite a bit. If I increase the box material FG multiplier to 10, it get close to production use, especially since the final material will have a texture on it, which will help hide some of the splotchiness.

The only problem now is that the floor material, to which the light will be illuminating, is quite heavy with the size of the texture, and complexity of reflections. Which means the light solution for the image will probably take a huge time hit.

I guess we will see... This is not a global solution that can be used on all projects, but for small project it might be fine.

[Wobi]

Me again,

hot chip, could you please give us some more information on this "hidden" light shader inside the production.dll? I can't help but I really cannot believe this. I mean there is quite some discussion about this topic on the net and I NEVER EVER read something about this "only-mental-ray-workshop participants-know-of"-Shader. Sry for that, but you know, this shader would be soooo useful for many of us and then you say its right there in the production.dll and only the mi-file is missing... well that sounds just... STRANGE!!
So it would be nice if you could get a little bit more specific of how you saw this shader in action and so on... cause I would definitely start a thread on mental-images forum about this topic if it was definitely FACT!
So please, enlighten me

EDIT: Sry, aber ich kann das einfach nich so recht glauben irgendwie, weil ich wie gesagt noch nichtmal ansatzweise irgendwas darüber im Netz gefunden habe, also was genau ist dran? Evtl. kannst du da auch nochmal nachforschen?!? Weil wenn das stimmt und man würde irgendwie ne passende-mi dazu kriegen, dann wär das natürlich schon genial... ENDLICH ECHTES OBJECTLIGHT!!!!!

[banned]

Hi Wobi,

ich kann dir leider auch nichts genaueres sagen. Auf dem mental ray Workshop meinte Steffen Römer von mental images, das zwar der Shader in der production.dll vorhanden sei aber noch nicht offiziell supported wird, weil in 3dsmax das Lichtsystem noch anders läuft und paar andere Dinge. Mehr war aus ihm nicht heraus zu holen. Ich nehme stark an, das sie da noch Probleme haben mi+AD. Was das Vray 1.5 SP3 kann, ist nun wirklich der Hammer.

mfg
hot chip

[Wobi]

Hmm, ok schade. Die könnten ja zumindest mal ein mi-file dazu rausrücken auch wenn der shader nicht offiziel supported wird. Im Grunde haben wir doch alle hier sowieso erstmal die ganzen Shader in 3ds und maya freischalten müssen um überhaupt daran zu kommen. Naja, komische Unternehmenspolitik haben die da, aber gut...
Aber wie sieht das eigentlich aus mit so einer DLL aus? Also ich hab da quasi null Plan von, aber im Prinzip ist doch so eine DLL nur eine vorkompilierte Bibliothek für Funktionen, Variablen, Konstanten, etc.. Dann müsste man doch auch irgendwie die Funktionen da rausziehen können bzw. zumindest die Funktionsnamen und Anzahl der Argumente und so weiter erfahren können, ODER? Hier gibts doch ein paar Programmier-Spezialisten! Weiss da jemand Bescheid und wenn ja, kann da nich mal einer reingucken???

[jb_alvarado]

Dann müsste man doch auch irgendwie die Funktionen da rausziehen können bzw. zumindest die Funktionsnamen und Anzahl der Argumente und so weiter erfahren können, ODER? Hier gibts doch ein paar Programmier-Spezialisten! Weiss da jemand Bescheid und wenn ja, kann da nich mal einer reingucken???

Würde halt alles Richtung Disassembler und Decompiler gehen, und sowas ist nicht erlaubt und verstößt gegen vorhandene Copyrights. mkshader wird wohl auch nicht an die Info rankommen.

[Wobi]

Würde halt alles Richtung Disassembler und Decompiler gehen, und sowas ist nicht erlaubt und verstößt gegen vorhandene Copyrights. mkshader wird wohl auch nicht an die Info rankommen.

Hmm, schade eigentlich. Naja, wahrscheinlich häts eh nix gebracht. Aber das is schon irgendwie mies, da gibts so nen shader und Keiner kommt ran, lol. Dann kommt einem ja schon der Gedanke ob man sich vllt doch mal lieber Vray o. ä. anschaut...

[banned]

da kommst du erst recht nicht ran, die haben eine andere Philosophie. Mann mus mit den Vor und Nachteilen leben.

[Wobi]

Ja aber ich will doch nur endlich echtes Object-Light...

So, ich render jetzt nen Teapot mit nem Omni-Light und nem roten Blinn-Shader ohne Gammakorrektur... einfach herrlich! Das steigert die Motivation ungemein...

Naja, dann heissts wohl einfach warten bis die da mal in die Pötte kommen...