Rendering a complex scene

[sebbiwee]

Hello all,

first of all, i am new to Houdini and this forum.

I am currently planning a more complex project.
Most of it(if not anything) should be done in Houdini and it is, simply said, pretty much a set of PyroFX.
In view of the rendering process, i would like to split the scene in different parts, so i can easily adjust most of it in Nuke in compositing. As an example i think about having shattered stones on the ground, levitation up at a given point in the scene. Those stones should be lit by an fire kind of orb floating around.
Right to the point, my main question here is the stuff regarding the lighting information.
In case i do want to render out the floating stones for themselves, will i need to have them in the same houdini scene to get the lighting information from the pyro orb? I guess it is possible to render out just the stones WITH the correct lighting from the orb but WITHOUT the orb itself?
What would be the best way to do so? Because i am going to have more PyroFX all intendet to light up the scene as a whole.
Do i need to set up anything in one hipfile? Or is there some kind of cool stuff i do not know about, yet?
I'm afraid(almost sure^^) the scene could get too big and not to be handled anymore soon…
Generally said i am asking if there is a good way to split up my scene in different stuff/models and when it comes to rendering each model for itself, i of course do want the lighting take effect for every part of the scene.

That really puzzles me and i hope, someone can help me!

Thank you and
cheers!

[LaidlawFX]

First off welcome to the forums, and the best of luck on seeing your project through.

I'll break my answers line by line. 

On 4/14/2017 at 9:13 AM, sebbiwee said:

Most of it(if not anything) should be done in Houdini and it is, simply said, pretty much a set of PyroFX.
In view of the rendering process, i would like to split the scene in different parts, so i can easily adjust most of it in Nuke in compositing. As an example i think about having shattered stones on the ground, levitation up at a given point in the scene. Those stones should be lit by an fire kind of orb floating around.

So with this information in mind, you are going to have a few key ingredients in your scene; Volumetrics (Pyro), Geometry (Stones), Volumetric Lighting/Lighting, plus the orb(combo). For each one of these the elements they'll be further broken down into their parts/elements/components i.e. the constituent parts of the orb. Beyond just making the components each one represents what you are passing off to Nuke and how you will be breaking it apart in Houdini to light and render. I would recommend making a storyboard of the sequences, or a sketch of the shot and listing out exactly what each element is made and composed of afterwards. Not magic or iron per say as they are description, but the orb has a lighting bolt inside it, the shell of the orb is more like a bubble than glass ets, it radiates outwards, it is deforming, etc.. Then you can break out the "how" each are created in Houdini i.e. the rocks are a hand model shape because it was a statue, as opposed to noised based sphere, and they are voronoi fractured and hand animated, and they will be geometry done in sops. The "how" you will do each element you can fill in over time as you research and learn, but identifying the elements so you know how to process them will allow you to get more direct solutions especially for Lighting and Rendering. There are several paths to process everything, especially if you are going to post process it in Nuke.

On 4/14/2017 at 9:13 AM, sebbiwee said:

In case i do want to render out the floating stones for themselves, will i need to have them in the same houdini scene to get the lighting information from the pyro orb? I guess it is possible to render out just the stones WITH the correct lighting from the orb but WITHOUT the orb itself?

Preferably you would have your lighting source and your geometry in the same scene. You will either use multiple render output driver, i.e. mantra nodes in out for each main element with render passes (extra image planes) for each aspect of lighting. Or you can you render it all in one beauty pass and use a ton of render passes. Additionally you can use Deep Compositing in Nuke and be able to really adjust your scene. The closer you get to your beauty shot in render the less work in Nuke you need to do and vice versa. 

On 4/14/2017 at 9:13 AM, sebbiwee said:

What would be the best way to do so? Because i am going to have more PyroFX all intendet to light up the scene as a whole.

Once you define all your elements it is more straight forward to answer this. General Voumetric Lighting is slightly more expensive than using a proxy light source i.e. you do not necessarily need to use the pyro fire to emit the light, you can use a spot light that has a noise on it. This is really scene dependent. Generally volumetric lighting requires a lot more noise controls to get a smooth falloff of light, but adjusting this to how your flame bounces may be tricky. Really it depends on the setup. Generally aim for a singly beauty pass and then break out each element to render separately.

On 4/14/2017 at 9:13 AM, sebbiwee said:

Do i need to set up anything in one hipfile? Or is there some kind of cool stuff i do not know about, yet?
I'm afraid(almost sure^^) the scene could get too big and not to be handled anymore soon…

The scene will allways get a bit big, but once you realize what you need you'll be able to remove a lot of dead components. Houdini itself will take anything you throw at it, but your hardware may be a problem. If your scene gets really big then you may need to split out elements to be processed on a farm.

Generally speaking there are years worth of things to learn about, and then just when you think you have mastered it all, a whole new wave of stuff will come in.  

As far as straight workflow for your first project of this scopr, I would design each element currently in a separate scene file, and have a scene assembly in another. Imagine you are working on a team and you would pass this to a lighter and then a compositor. You only want to pass off the elements you need, and since you are doing R&D there will be a lot of stuff you need to figure out. Also this allows you in the scene assembly phase to collect the final outputs of each element as a cache. Generally you never render an FX direct from it source but from a cache. You do not want to pay to run the FX each time you need to render. This also allows you use instancing and delayed load more effectively.

Good Luck.

-Ben