Morning,

I've been playing around with Sky Light which i plan to use to light a mountainous scene. I'll be provided with a scene with fracturing and fluid sims in a later stage. There are little topics on lighting environments in Houdini, everybody's doing effects.

My question is can we apply an environment map in Sky Light instead of using “Realistic” or “Ramp” parms?

Do the peeps out there use Houdini to light large-scale scenes or do they bring it out to other 3d packages instead? Thought i could get some useful opinions, anything is appreciated.

Here are some reference images, this is the mood i like to achieve.
One of them is an awesome shot from World of Warcraft: Cataclysm Cinematic!

Here's the link if you want to relive the epic-ness,
http://www.youtube.com/watch?v=Wq4Y7ztznKc [youtube.com]

eitht
I've been playing around with Sky Light which i plan to use to light a mountainous scene. I'll be provided with a scene with fracturing and fluid sims in a later stage. There are little topics on lighting environments in Houdini, everybody's doing effects.

I have been watching the forums for years and yes many posts are focused on vfx but there are a lot of posts on shaders, lighting and rendering as well. Both here and on the OdForce forums.

Also check out the Customer Stories on the main Side Effects site for customers that have used Mantra.

eitht
My question is can we apply an environment map in Sky Light instead of using “Realistic” or “Ramp” parms?

You can answer this question yourself just by spending 1 minute parsing the parameters for the Environment Light. You will quickly notice that disabling the parameter “Enable Sky Environment Light”, the “Environment Map” parameter becomes available for you to reference your HDR environment map.

I would not do this though. I would leave your Sky Environment Light. I would add an additional Environment Light in your scene and reference your HDR image in that second Environment Light. You can use as many Environment Lights in your scene as you wish then enable and disable them either by using Takes or specifically set up Output Drivers using the various options available.

If you wish to use two or more environment lights together, you can enable one or more image planes in the Mantra ROP and render out per-light exports for all the various shader exports: Direct Diffuse, Direct Specular, etc. The overhead isn't that significant other than the additional disk space required.

If you don't want to use the Sky Environment Light then just disable the parms “Enable Light” and “Enable Light In Viewport”. Simple. No need to delete it.

eitht
Do the peeps out there use Houdini to light large-scale scenes or do they bring it out to other 3d packages instead? Thought i could get some useful opinions, anything is appreciated.

Yes to both.
Yes some render environments in Mantra.
Yes some export scenes to shade/light/render using other tools including proprietary.

More robust pipelines will split each part of the scene in to foreground, mid-ground and background elements and render each of these in a different pass and then composite them together. These are general approaches to lighting large environments that is not tied to any software. Lots of information on the web as to how to approach the efficient rendering of environments in production.

can we apply an environment map in Sky Light instead of using “Realistic” or “Ramp” parms?

All the Sky Light really does is generate an environment map used by the environment light. So, while there is no option to specify an environment map in Sky Light, you can use that map directly in the Environment Light from the shelf.

Incidentally that tool creates the same object node as the sky light, but turns off the “enable sky environment map” toggle, which enables the Environment Map parameter, where you can specify your env map.

A second environment light never crossed my mind. Hehe

If i may ask another question, i understand realistic lighting can be achieved using properly taken HDR images. Curious whether there are situations where long/lat HDR images etc are used for full CG shots?

The only reason i can think of for using it in full CG is probably to get nice inaccurate lighting without having to light traditionally.

Cheers to jeff and rafal.



eitht.

eitht
If i may ask another question, i understand realistic lighting can be achieved using properly taken HDR images. Curious whether there are situations where long/lat HDR images etc are used for full CG shots?

The only reason i can think of for using it in full CG is probably to get nice inaccurate lighting without having to light traditionally.

An HDR environment map was a revolution in lighting shots a few years ago to achieve realistic lighting of CG props that perfectly matched the actual plate. It gave TD's a way to quickly light shots with what seemed like guaranteed results, as long as the HDR image was valid for the shot. As we all know an HDR image captures the environment lighting with values ranging from 0 to in the tens of thousands for very bright objects like the sun or very bright lights close to the camera that took the images.

It doesn't matter whether the HDR image is the traditional cross (box) format or the spherical (lat-long) format, if they are a true HDR image they will be at least 16 bits in depth (or the old 8bit with alpha) and have values in the image that capture the darkest and brightest objects in the real scene. They are both meant to capture the lighting in an environment from a given position. The Houdini Environment Light works with both the Cross and Spherical format. In Houdini it is referred to as Environment based lighting and you use Environment Lights to reference the HDR images.

I see an HDR image as just another light type. Yes you can create your own HDR image and it can contain any kind of lighting information you like from realistic scenes to highly stylized unrealistic environments.

It's all up to you how you use the HDR images. It is just another light source so treat it as such.

Woo, you really got me thinking in a new direction and yes, “highly stylized lighting” would be a cool thing to apply the next time i do a personal project or even now the one i am currently working on.

Always had a rigid mentality that HDRI are only used for integrating CG to live plates, maybe i was constantly exposed to presentations or papers on HDRI being used in live-action films.

/thumbs up to you and your time, jeff. :wink:



eitht.