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View Full Version : Perfect composite of 3D and live footage - how?


Cman
02-26-2005, 07:30 AM
Please, looking for tuts and tips (fee or free) to create "perfect" composite of 3D and live footage.

I'm thinking stuff that was done for "Walking with Dinosaurs" and the upcoming "Dragons", or various commercials and music videos with seamless composites and lighting/color interaction.

Thanks for any help.

edit-

btw,
I have syntheyes and know how to use it.
I have Lightwave and know how to use it. (and access to 3dsmax)
I have AE and know how to use it. (and access to Combustion 3)

I'm looking for more advanced tips to take it to the next level, to learn how to use these tools well.

Must I use some kind of light probe of a location to match lighting in 3D?
Must I paint mud/scratches/dents into every 3D object to make it look real?

My current problem is a 3D set just don't quite look right with comped over actor. When the camera tracks it looks kinda decent, but once the camera is still, the 3D environment begins looking very flat.

Also, all original footage is SD. (I fear part of my problem is dealing with SD)

thanks again.

Aruna
03-01-2005, 10:08 PM
Those examples you mention are 3D elements composited in a live action environment.. You're trying to compositing a live action actor into a 3D set, I assume something like The World of Tomorrow. As well, some of the shots in the films you mentioned are completely 3D, and have been controlled from the inception of the show.

Even though you "know how to use" those packages you mentioned, that's not going to get you very far. You've got to be diligent and try to find some other references of what you want to accomplish.. Basically, if you're doing this sort of 3D/2D integration, you would have taken measurements of the actor and the environment he was in, lit him correctly so that he would be put into the 3D set accurately, and make sure that if you WERE doing a moving shot, that everything would be locked down together correctly. It sounds like you've got some arbitrarily shot footage and you're trying to create a set to fit the actor in. It seldom works well without some foresight into planning the originial video shoot.

To answer your two questions:

Must I use some kind of light probe of a location to match lighting in 3D?
Must I paint mud/scratches/dents into every 3D object to make it look real?


Yes.

Cman
03-01-2005, 11:44 PM
Those examples you mention are 3D elements composited in a live action environment.. You're trying to compositing a live action actor into a 3D set, I assume something like The World of Tomorrow. As well, some of the shots in the films you mentioned are completely 3D, and have been controlled from the inception of the show.

Even though you "know how to use" those packages you mentioned, that's not going to get you very far.

As I said, I'm trying to learn how to use them well - meaning "in concert".
The reason I'm asking for help here is because I already know I'm not getting very far.


You've got to be diligent and try to find some other references of what you want to accomplish.. Basically, if you're doing this sort of 3D/2D integration, you would have taken measurements of the actor and the environment he was in, lit him correctly so that he would be put into the 3D set accurately, and make sure that if you WERE doing a moving shot, that everything would be locked down together correctly. It sounds like you've got some arbitrarily shot footage and you're trying to create a set to fit the actor in. It seldom works well without some foresight into planning the originial video shoot.

Okay, it is not at all that situation.
I have shot footage on a fairly carefully controlled situation - meaning I have markers set to represent the Origin, as well as measured distances from that origin "on axis" as well as off to capture parallax.
The points are not measured with laser precision, but I'm confident they're accurate within 1/8". And actually, the track was/is spot on (no float) - it's the composite that always causes me trouble.

I also have lens focal distance measurements to try and match angle, but LW doesn't apply lens distortion, which I have decided I may try to measure or figure out, in case that could help.
As my original footage is shot with a solid green screen, there is nothing there to see for distortion - so I will add something, probably shoot a "lens distortion reference frame" next time.

About the lighting, I decided to do it in reverse - light the actor against the greenscreen, then match that lighting in the virtual set, since they'd be lit that way anyway were the set real.

As to my two questions - how does one do a "clean set" to look realistic?
What if the 3D set isn't covered with pock marks and mud and dents?
What if the set is "clean"?

I have ordered the DVDs from Gnomon about this subject, but any suggested tutorials to help explain this complex process would be welcome.

Thanks for taking the time to respond. :)

Cman
03-01-2005, 11:52 PM
oh yeah, there's also matching grain/noise - which I always read in tutorials as "then match the grain and you're done." Well, how does one do that?

What is it about the grain one should look for to see if it matches?
Is it just add enough to make it look close, or is there some technique one might use?

I'd gladly post a pic of the set tomorrow, and a sample composite frame, if you're willing to take a look.

Thanks again.

Aruna
03-02-2005, 01:16 AM
oh yeah, there's also matching grain/noise - which I always read in tutorials as "then match the grain and you're done." Well, how does one do that?

What is it about the grain one should look for to see if it matches?
Is it just add enough to make it look close, or is there some technique one might use?

I'd gladly post a pic of the set tomorrow, and a sample composite frame, if you're willing to take a look.

Thanks again.

Tip of the Week - Grain and Noise (http://www.digitalgypsy.com/vfxlog/archives/2005/01/tip_of_the_week_3.php)

Yes, if you have some stills of your project, that would go a long way!


As to my two questions - how does one do a "clean set" to look realistic? What if the 3D set isn't covered with pock marks and mud and dents? What if the set is "clean"?

What do you mean by this? Do you mean how to create a photoreal looking 3D environment? Well, you can use photographs of similar situations, either texture them onto your 3D set, or use the the actual photographs as a background. Again, post a pic of what it currently looks like, that'll help tremendously.

You can apply lens distortion in your comp package, and dial it in to match.

Cman
03-02-2005, 02:18 AM
Tip of the Week - Grain and Noise (http://www.digitalgypsy.com/vfxlog/archives/2005/01/tip_of_the_week_3.php)



LOL!
I discovered these just a few days ago. :)

I'll post some pics tomorrow.

Cman
03-02-2005, 03:12 PM
I just saw that you are the person to create those "Tip of the Week"!

Thanks very much for doing that and I look forward to following along in the future.

Attached is the final comp without the letterbox that they add before air.
Also there is a shot of the subject against green and the background still, both before any effects or cc.

The original video is BetaSP.

Thanks for taking the time to review these images. http://www.cgtalk.com/images/icons/icon11.gif

Cman
03-02-2005, 03:17 PM
Here is a larger version of the set.

The producers of this show tell me how they really love this, but the longer I watch the video, the more flat and lifeless the background becomes.

I'm really looking to make it "photoreal", or at least MORE real... Thanks.

Aruna
03-02-2005, 04:47 PM
Well... damn.. looks nice to me.. I can see what you mean by putting the actor in appropriately. There's no tried and true way to do this, but I'll toss out some ideas.. Since she was shot on tape, you'll notice that her edges and highlights look different, like bled through, she seems slight out of focus as well. See if you can mimic this type of look on your background set, by degrading the image using your comp package. Try blurring or defocusing the background slightly, that might help bring it together too. As well, some noise over the background so that both the live action and the set match. Putting some slight lightspill over her from the background might tie her in a little bit better too.

Since you've done so much work on the 3D set, I hesitate to recommend going back and dirtying back up like I wrote before. It's a possibility if you have time, but I'd put that last on the list.

Hope that helps a bit!

Cman
03-02-2005, 05:54 PM
Well... damn.. looks nice to me.. I can see what you mean by putting the actor in appropriately. There's no tried and true way to do this, but I'll toss out some ideas.. Since she was shot on tape, you'll notice that her edges and highlights look different, like bled through, she seems slight out of focus as well. See if you can mimic this type of look on your background set, by degrading the image using your comp package. Try blurring or defocusing the background slightly, that might help bring it together too. As well, some noise over the background so that both the live action and the set match. Putting some slight lightspill over her from the background might tie her in a little bit better too.

Since you've done so much work on the 3D set, I hesitate to recommend going back and dirtying back up like I wrote before. It's a possibility if you have time, but I'd put that last on the list.

Hope that helps a bit!

I will try more with degrading the background with blurring and noise. Yes she is soft, but for some reason she always comes out soft - cameras probably need tuning -or better yet replacement! :)

I think the bleed is due to my attempt at a light wrap.

I also plan to do some of your suggestions from before - shoot a 50% grey card to capture the grain, shoot some footage with a couple c-stands in the shot to check for barrel distortion.

Thanks.

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