Wondering about FX??

[purefilm]

This in sort is a film look question. I was watching transformers the other day and I was amazed how CG is intergrated into the film plates. I was thinking about the steps that go into these effects. First you transfer the film to 2k then your effects are built in the computer and composited into the film frames. My question is how do they create the film look with the CG animtion? There has to be some trick that effects artist are using to make it look like those elements where origianally film through the camera. I figure they have to add film grain and contrast to the CG elements?

 

[Bruce Allen]

1. Remove grain & lens distortion via filters.
2. Add effects.
3. Add grain back in via filters (and lens distortion if you wish).

Or skip the grain removal stage and just try to add the effects in over the top with the right amount of grain added to them with filters (tricky but often done for lower-end stuff or if you're out of time .

Even After Effects has degrain / regrain tools - they're actually not too bad!

There are ones that you can "train" to match grain, ones that try to simulate specific film stocks, etc. Check out the usual suspects - built in tools of the film compositing programs plus things from The Foundry, GenArts, etc...

Also remember the act of printing to film adds a layer of grain to everything as well at the end.


Bruce Allen
www.boacinema.com

 

[purefilm]

Thanks, that was really informative.

I have dealt with 3D modeling before, so how do they match the look and contrast to the film stock? There has to be some tricks we could use in out own productions.

What will happen when the effects are not outputted to film for the theater, but projected on a digital projector.

 

[Bruce Allen]

Thanks, that was really informative.

I have dealt with 3D modeling before, so how do they match the look and contrast to the film stock? There has to be some tricks we could use in out own productions.

Sometimes people try to get it really close in 3D. Often they render out a bunch of passes. If you have highlights, shadows, etc all separate, you can tweak a lot in a compositing program.

Either way, the final tweaking is done in a compositing program - eg Shake, After Effects, Fusion, etc. The same way you'd use Curves in Photoshop to try to make your 3D render's tone / color curves try to match the response of the film plate you're trying to stick it in to.

The most important thing is to get the black and highlight levels right. Eg same intensity and color balance as the live action film stuff.

What will happen when the effects are not outputted to film for the theater, but projected on a digital projector.

The same process as if you're printing to film. The effects people don't do two versions of a shot.

Maybe if you're an indie and you're going to be projecting digitally you'll add slight film grain over everything to make it look like a more expensive process involving film out was used somewhere along the line

Bruce

 

[Gavin Greenwalt]

I have dealt with 3D modeling before, so how do they match the look and contrast to the film stock? There has to be some tricks we could use in out own productions.

It's not really "matching the look and contrast of the stock" because the look and contrast of every shot regardless of what stock it was shot on will look different.

Lenses, lighting, atmosphere, smoke, flares, filtration, grading, telecine framing etc etc etc all affect the color and contrast of an image.

So in the end it just comes down to making it the same as the live action plate. It's all very subjective.

 

[jbeale]

FX "plate": trivia question

FX "plate": trivia question

So in the end it just comes down to making it the same as the live action plate.

Trivia question. When fx people talk about "background plate" for example, I understand this is just a still frame image of a background scene, probably larger than the output frame so you can pan around within it. Does anyone know where the term "plate" comes from? ...hand-painted scenery on a glass plate? Does this date back to the days of large-format photography on sensitized glass plates ?

 

[Gavin Greenwalt]

I had always assumed large format photography on glass plates since matte paintings already go by such a wide variety of designations. Also glass plate matte paintings go on top, calling them background would be kind of confusing.

I would be interested to know as well.

(Also 'background plate' has evolved in usage to include motion as well. But usage is pretty much random from my experience.)

 

[Peter McCully]

Trivia question. When fx people talk about "background plate" for example, I understand this is just a still frame image of a background scene, probably larger than the output frame so you can pan around within it. Does anyone know where the term "plate" comes from? ...hand-painted scenery on a glass plate? Does this date back to the days of large-format photography on sensitized glass plates ?

I'm not sure exactly where the term originated but your guesses are most likely right. However, the term "plate" doesn't refer to a still but to a filmed element - usually a background onto which CGI or other filmed elements are to be composited.

 

[Craig W. Bickerstaff]

There really is no simple answer to this question seeing as there are so many different ways of doing it.
but really pick up pretty much any dvd of a film with special effects and CGI in it there's always a little bit thrown in on the compositing process.
Color grading, match moving, interaction, Grain, matching focal lengths all sorts of things can be done extreme attention to detail is the difference between good effects and bad effects.

 

[RivaiC]

What amaze me is the integration to live people. How do they do that ? No tutorials or insight that i've ever read that explain this. Eg. Integration between Gollumn and Frodo

 

[Craig W. Bickerstaff]

What amaze me is the integration to live people. How do they do that ? No tutorials or insight that i've ever read that explain this. Eg. Integration between Gollumn and Frodo

It depends on the situation, But in the case of Gollumn it's a lot of painstaking roto scoping.
In other cases you can do all kinds of tricks with wires or blasting air at the person maybe even replacing that area with CGI in post.

 

[Michael "Dorkman" Scott]

It depends on the situation, But in the case of Gollumn it's a lot of painstaking roto scoping.

To be more specific, Gollum was performed live by Andy Serkis, and in scenes where he physically interacts with Frodo was almost always actually interacting with Elijah Wood, then painstakingly removed from the frame, then replaced with the digital Gollum.

Doing it this way creates a lot of happy accidents that sell the realism. For example, when Gollum first attacks them at their campsite in Two Towers, at one point while he's running around his foot catches one of the blankets and gives it a little twirl. This would have been a difficult effect to achieve with a clean plate, if the animators thought of it at all -- they would have had to run a cloth simulation and everything. But it was the real blanket moving because Serkis' foot actually caught on it, and they used that in their Gollum animation.

Really, a lot goes into matching CG to live action. Pick up a copy of Cinefex if you really want the details -- the current issue is Transformers.

 

[RivaiC]

Got it, Cinefex !

 

[Michael "Dorkman" Scott]

I probably should warn you though: it's an industry mag, which means that they make no real attempt to explain a lot of the more technical stuff. There's a lot of jargon and references to practices that aren't necessarily intuitive. Be near Wikipedia while you read. :wink:

 

[poiboy]

How about regraining cg elements for Red Camera stock

 

[Priyesh P.]

I probably should warn you though: it's an industry mag, which means that they make no real attempt to explain a lot of the more technical stuff. There's a lot of jargon and references to practices that aren't necessarily intuitive. Be near Wikipedia while you read. :wink:

Yeah.

Purefilm, ever heard of subsurface scattering? Subdivision surfaces or (the outdated) nurbs (don`t confuse with NERDS ;-)? Global illumination / ambient occlusion etc.? - but "unfortunately" you should know how those things work since they tremendously reduce the (still tremendous) effort required to make creatures and machines look real. Film grain and color corrections are the last steps in the pipeline, before that, you`ve to make the cg elements look as "real" as possible.

To me, the biggest step in cg was the "monte carlo" radiosity - suddenly it took way less time for tweaking and lighting than with raytracing. Subsurface scattering is a bit slow, but nontheless a fantastic progress for cgi.