Image based lighting without Radiosity?

[kuui]

I#m not aware of any method to use IBL without GI in c4d.

[STRAT]

well, IBL is a radiosity/gi effect, so no, you cant do it without the AR module. you can fake it with a conventional lighting rig, but whats the point? a major pluss of IBL is to light the scene without fannying about with any lights, which is what you're after.

[mustardseed]

This may not be what you're after but from what I understand, you can fake it with minimal fuss using 50grey, which can generate a light array based on the color and luminance of an image map. In fact hasn't it been recently been updated and called LightGen?

[azazel]

Yeah, lightgen can do just that. Anyway, IBL is IMO more useful for ambient/fill light, you would still find at least a normal key light useful (getting sharp shadows from ibl can be tricky.

[hundredthirtyseven]

The only problem with lightgen is that it cannot use HDR images. Only jpg, tif, tga...etc. is good.

[acmepixel]

Photoshop CS2 (v9) can open and save HDRI as different formats. Only HDRI can retain the extra levels though. But then LightGen can use the converted image to colorize the lights that are faking the luminance.

Another trick is to use Radiosity or Stochastic, but at a lower percentage, thus mixing Radiosity, HDRI, Raytracing and phong in a single render pass. Also, assigning tags to objects to be excluded from GI so that only the floor/ground will have the soft GI shadows, will speed things up.

Radiosity/GI CAN be used and it can be very fast IF you really tweak all the options that Cinema provides. Sometimes Radiosity, when tweaked and used in hybrid mode, can be much faster than a 50+ light dome with all lights casting shadows.

[BazC]

The licensed version of Lightgen can use HDRIs, I think possibly the earlier releases couldn't? It should do exactly what you want!

[Kuroyume0161]

Settled then. If I implement IBL import, the user will need AR to support it.

[jtbullet]

I think that AR support is a great added feature for interposer. Many professionals will use it, and it is good to support the feature. It may encourage others to migrate to AR as well. And it definitely adds to the useability as well for interposer. now make an easy hook up for clothilde for the hair and clothing imports and you are talking about a major character studio for c4d! Interposer can be much more than a poser to c4d plug. Hook it up to motionbuilder's free version and we'll see some incredible things.

[Incarnadine]

Sounds good to me.

[hundredthirtyseven]

The licensed version of Lightgen can use HDRIs, I think possibly the earlier releases couldn't? It should do exactly what you want!

Can you tell me then how you use HDRIs with Lightgen? I have a licensed version of the plugin, and it doesen't recognize HDRIs.

[acmepixel]

You can also use HDRI's in the Environment Channel and the reflections and specular hilights will reflect off of reflective surfaces without using Radiosity.

[c-montesano]

To use an HDRI with LightGen, just load it like you would any other image, although it will be read as an LDR image because as far as I know, there is no SDK support for 48bit images.
And I believe AR is required to load an HDRI image.
So if you can see the HDRI image in the material preview, then LightGen can see it.

-Chris

[hundredthirtyseven]

I have just discovered what the problem was. First: the texture must be in absolute path. Second: you can't use an HDRI under a Filter shader with Lightgen. It creates weird colors.

[c-montesano]

you can't use an HDRI under a Filter shader with Lightgen. It creates weird colors.

that has now been fixed. HDRIs + filters should now work fine.

-chris

[mrivers]

I'm wondering if there is a way to do image based lighting (using a non-HDRI light probe image) without Radiosity.

Yes there is, but it is painfully slow. All of the objects must use the Reflection channel for their color, and the Dispersion to simulate how dull or polished the surface is. Objects using Luminance can be used for you're world sphere, and/or lights.

for example:
(bah, I can't get the image tags to work)
http://home1.gte.net/res0q9bt/rad1.jpg
http://home1.gte.net/res0q9bt/rad2.mov
http://home1.gte.net/rad1.jpg

[Blur1]

It would be good if there was a low-tech IBL technique (besides dome lights). I have mentioned this before but a simple rgb bent normal lookup into an environment map (either hdri or ldri) would do this. You can even do it in a compositing program in "real time".
This would require an ambient occlusion shader that could also output bent normals, such as dirtmap, the mentalray shader. From there, you would use the "bent normal" info to lookup the environment map, and render the result into (I assume) the ambient channel of your material. The resulting image, when combined with a key light and ambient occlusion, is pretty effective and does not require anything more exotic than a ray tracing calculation for the initial bent normals pass.

Having said that with the small amount of testing I have done with C4D since I bought it, I'm impressed with the speed of IBL using radiosity. It is far faster and more predictable than say mentalray final gather.

I have also found that a quick cheat than can be effective is to assign your environment map to the whole scene as a spherical projection. The result is different to doing this in the reflection channel because of the way the reflection vector works.
Pre-blur it (make sure it remains seamless) or blur it from within the material. Although not as accurate as other IBL methods, it's pretty useful as an extra pass.

Michael

[Kuroyume0161]

It would be good if there was a low-tech IBL technique (besides dome lights).

Yes, it would.

Having said that with the small amount of testing I have done with C4D since I bought it, I'm impressed with the speed of IBL using radiosity. It is far faster and more predictable than say mentalray final gather.

This has nothing to do with quality or speed. The question was in relation to my plugin which imports objects/scenes which may have ldri IBL 'lighting' and I really do hate to go for the "you can use my plugin if you have R9.2 Engineering Studio Bundle XXXL". :) It reduces the market for the plugin since the only way to do Radiosity is if you have the AR module. I plan on making an R9 version in order to provide sub-poly displacement support for those who have it and want it, but the current version without this support is as low as I can go to have the widest support possible. The reason for a separate plugin version is because there are literally no alternatives for SPD in versions before R9 (short of writing my own sub-poly displacement support - yeah, right). ;)

Not being argumentative, just reminding of the original reason for this thread.

I have also found that a quick cheat than can be effective is to assign your environment map to the whole scene as a spherical projection. The result is different to doing this in the reflection channel because of the way the reflection vector works.
Pre-blur it (make sure it remains seamless) or blur it from within the material. Although not as accurate as other IBL methods, it's pretty useful as an extra pass.

I don't get you here. Assign an environment map to the Environment channel of the material of what exactly? Whole scene is meaningless since C4D documents cannot have materials. ;) Do you mean every object in the scene?

Thanks,

[Blur1]

I don't get you here. Assign an environment map to the Environment channel of the material of what exactly? Whole scene is meaningless since C4D documents cannot have materials. ;) Do you mean every object in the scene?

Thanks,


My apologies, I inadvertently hijacked your thread. In other packages (I'm sure is applicable to C4D) I project a blurred spherical environment map around (yes) all the objects in your scene, using world space (so the texture "swims"), probably in the ambient channel, although I'm just as likely to apply it in the luminance channel, render it separately at 100% luminant and comp as I see fit. I'm not totally au fait with C4D material channels yet but imagine they are the more or less the same as other 3D programs!

Michael

[Kuroyume0161]

My apologies, I inadvertently hijacked your thread. In other packages (I'm sure is applicable to C4D) I project a blurred spherical environment map around (yes) all the objects in your scene, using world space (so the texture "swims"), probably in the ambient channel, although I'm just as likely to apply it in the luminance channel, render it separately at 100% luminant and comp as I see fit. I'm not totally au fait with C4D material channels yet but imagine they are the more or less the same as other 3D programs!

Michael

That's okay. Now see, there is the problem. C4D materials cannot be used independently of objects. They are referenced by objects only. The closest way to do that (similar to HDRI in C4D), is to use a sky or sphere object. But that gets right back to the same problem (environment maps don't produce ambient lighting, only pseudo-reflection, and luminance doesn't work at all as ambient lighting). No swimming in C4D allowed! ;)

That's the other thing. There is no ambient channel in C4D. There is an Ambient Illumination setting for lights in C4D, but this will not work anywhere near IBL. C4D lights are treated as point or area ray emitters, not as GI. GI seems to be only calculated with Radiosity, which requires the AR module.

[Blur1]

That's okay. Now see, there is the problem. C4D materials cannot be used independently of objects. They are referenced by objects only. The closest way to do that (similar to HDRI in C4D), is to use a sky or sphere object. But that gets right back to the same problem (environment maps don't produce ambient lighting, only pseudo-reflection, and luminance doesn't work at all as ambient lighting). No swimming in C4D allowed! ;)

That's a shame, you can obviously do it with camera mapping...that is, make multiple objects receive the same projection as if they were one object. But we need a spherical projection. This way, it is similar to a dome light rig but the illumination contribution is "faked" ...(see below).

That's the other thing. There is no ambient channel in C4D.

That's OK you can use the Layer shader, or do it as a separate pass and comp it (preferable).

Sorry, won't hijack your thread any longer!! PM me if you want to me to send a basic example of what I'm talking about.

[Aurety]

MAJOUL, a french developper known for another great plugins, did this really helpfull Xpressions : QUICK DOME 1.1 . You will find some others plugins on his website : http://perso.wanadoo.fr/archizone/Accueil.htm

The file : Download (http://perso.wanadoo.fr/archizone/DIVERS/COFFEE/Quick_Dome.c4d)

Here my little translation about the expression :

http://perso.wanadoo.fr/archizone/images/qd_log.jpg

An XPresso who offer the way to generate and set settings to a lightdome with the possibility to use a picture to fake the Radiosity.

http://perso.wanadoo.fr/archizone/images/qd_du.jpg


Nouveauté dans la version 1.1 la fonction Rayon de lissage.
NEW in version 1.1 : The smooth/falloff radius

Download and open the file in Cinema 4D V8 or greater and add a light to the scene.

http://perso.wanadoo.fr/archizone/images/qd_tut1.jpg

Move the XPresso on the light

http://perso.wanadoo.fr/archizone/images/qd_tut2.jpg

Now the domelight is generated and ready to use.

http://perso.wanadoo.fr/archizone/images/qd_dome.jpg

To set the size of the lightdome, use the setting : Rayon

To minimize the bottom of the lightdome, use the parameter : Limite dôme. Materialized her by the white circle.

For the number of lights, use the parameter "Iterations", defined by the segmentation of the sphere.

To applicate a picture to your dome , you will just to add it with the input box : Image.

IMPORTANT !!! CAUTION !!!


Take care about the path of the picture, it will be absolutly defined on the preferences settings, and of course the picture placed within one of these paths.



http://perso.wanadoo.fr/archizone/images/qd_acces.jpg

If no image was validate and placed on the lightdome, the textfield "image validee" return : Aucune image n'est validée ( No image is validate )

http://perso.wanadoo.fr/archizone/images/qd_tut3.jpg

To validate the picture, you will just to check the box : Valider l'image au Dôme
This checkbox stay never checked, only one time to validate the picture.

If the picture is validate , the name of the picture appear in the textfield Image validée

The setting : Rayon lissage give the possibility to increase the analyse for a picture area calculated in this way : Carre = 2 x Rayon lissage + 1 px.

To revalidate the picture with the new settings, check another time : Valider l'image au Dôme


http://perso.wanadoo.fr/archizone/images/qd_tut4.jpg

To colorize the lightdome, you'll need to check the settings : Couleur Image et Saturation to dark or bright the colors.

For the illumination, you'll need to check : Luminosité image and use Intensite to increase or decrease intensity.

If both cases are unchecked, the color and strenght of the Quick Dome light are used.

To change the color , check the box : Modifier la teinte and use the slider to choice your own.

http://perso.wanadoo.fr/archizone/images/qd_tut5.jpg

Now if you want to change some others parameters like the shadows mask, shadows, etc... change these settings on the light called Quick-Dome Light.

[hundredthirtyseven]

Why is this plugin better than Lightgen?

[Aurety]

:argh: uhhh, I've never said this plugin is better than lightgen ! Just to offer an alternative. Sorry for that ! :sad:

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