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CGI with real scene

Posted: Sun, 1st May 2005, 6:10pm

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shadu

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I know a good part of any good CGI integration with a real scene is light. But is there any trick to simulate the interaction with the real environnement? Like the grass on the floor when the creature walk?

Here is a exemple:

www.imaginethisproductions.net/movies/essai_troll_divx.avi

I want to put some effect on the floor to help the CGI to look better and i search for some trick for that.

Shadu

PS: That some preliminary test for our next movie
Posted: Sun, 1st May 2005, 6:26pm

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Rawree

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The best way to get good CGI interaction is with GI, easiest way to do that is with a 3rd Party renderer like Mental Ray or Vray (basically because it mimics real light).

For the ground you need to find out about ambient occlusion (it's got something to do with shadows underneath objects or some jazz like that) so that it looks like the object is actually making contact with the ground and not just hovering. Then you just need the regular shadows (or not depending on the scene).

Something I made a while ago:


Notice how that shadow makes each of the legs seem to be resting on the floor and not above it - it's fairly subtle.
Posted: Sun, 1st May 2005, 6:32pm

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LilCaesars

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Just my $.02 I'd suggest shooting the footage with a better camera before adding in cgi. It really degrades the film when you have an amazing effect placed on poorly shot video.
Posted: Sun, 1st May 2005, 6:38pm

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Rawree

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AcjPictures wrote:

Just my $.02 I'd suggest shooting the footage with a better camera before adding in cgi. It really degrades the film when you have an amazing effect placed on poorly shot video.
I disagree. Badly filmed footage often allows you to have the most convincing CGI: Shakey cameras and Noise on the picture, when matched properly really do look much better than locked down, perfectly clean footage (whoo how exciting), the harder it looks to match, the more convincing it is when done properly.
Posted: Sun, 1st May 2005, 6:53pm

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The video machine

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yeah but that means shelling out for icarus, unless you got it for free. Or unless you're willing to spend hours going through each frame, with the video footage in one of the viewports, matching up every last picture of a 700 frame animation... didn't happen to me or anything...
Posted: Sun, 1st May 2005, 6:59pm

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shadu

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It was a test shoot make during a rainy day...

The model, by the way, is made and animated with poser.

Shadu
Posted: Sun, 1st May 2005, 7:35pm

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LilCaesars

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I don't know most movies I see that try stuff like this try these huge blockbuster effects and forget about other things such as a story and shot placement. I would rather a little story some good camera work and maybe a few muzzle flashes than a pixely guy running around chased by an impressive looking 3d troll. Of course we are all entitled to our opinions. Rawree nice model for the macine gun biggrin
Posted: Sun, 1st May 2005, 7:39pm

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Redhawksrymmer

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Rawree wrote:

The best way to get good CGI interaction is with GI, easiest way to do that is with a 3rd Party renderer like Mental Ray or Vray (basically because it mimics real light).
What is GI?
Posted: Sun, 1st May 2005, 8:25pm

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The video machine

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Global illumination, it gives that little shadow and makes the render photoreal if used properly. Use vray, go to renderer on the render options menu, go down to the drop down menu, INDIRECT ILLUMINATION, and check the on box. MAke sure yuo have a white background to make the shadow, and a black background for the plane which your model is on. You'll need an omni light, but switch it off or put the multiplyer to 0.1.

This will make it look really good.

Last edited Mon, 2nd May 2005, 7:22pm; edited 1 times in total.

Posted: Sun, 1st May 2005, 8:30pm

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Aculag

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Rating: +4

The video machine wrote:

Ps. it'd be nice if you would rate me up...
Is that a joke or are you serious?
Posted: Sun, 1st May 2005, 8:35pm

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shadu

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I have no intention to use this kind of shot in our next movie. Big movie with a lot of talent and $$$ can but not us. We have made a short story board for using this model... No big shot with minimal interaction with actor... The entier scene was design with the difficulty of CGI in nobudget movie in mind. I think it will be good. But most try for it first. So this is the test one of many. That test was made mainly to learn poser and the problem accounter during the integration.

Video machine, i saw the site of Vray. Can i use the demo or free vray for doing this? 800$ is a lot for some test and a amator movie.

Shadu
Posted: Sun, 1st May 2005, 8:44pm

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Rawree

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I really really hate it when people get CGI in movies wrong as ACJ clearly has:

Where did the idea come from that the minute you introduce large CGI sequences into a movie it loses credibility as a "serious movie". People always seem to assume that you can't have a gripping story and camera work and lots of CGI, oh God no - the shots have to be badly framed, the camera work boring, the story will be lame and the characters unbeleivable.
CGI doesn't ruin movies or make them any worse than movies without (Bad CGI is what can weaken a movie - it can't ruin a good movie).

Usually the people who bang on about CGI being overused and looking fake are usually the ones who don't understand it (the ammount of work) or the people who just bash CGI to be "cool" I guess (look at what people say about Ep2 - most of the stuff they say is a load of crap).
A good movie and a movie with lots of CGI are not two exclusive things!

As you say, we're all entitled to our opinions. Thanks about the model, I was gonna use some in a short project but decided against it in the end.

One final thing: Poser probably can't do GI (rather unsurprisingly) and I really would suggest looking into getting a 3D app if you want to use extensive CGI like this.
Posted: Sun, 1st May 2005, 9:05pm

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CX3

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Good feedback Aculag.

+1
Posted: Sun, 1st May 2005, 9:15pm

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LilCaesars

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I remember someone saying something about using a steadicam a little back. Its having a very fancy move and having the rest of your film not match up to it. You can have a spiffy flashy title sequence etc. and the rest of your film may suck. I think that before you try and jump into a huge flashy effect you should make sure you got the basic down first. I have nothing against CGI I think films have reached an unequaled level because of it. I just think you should start with basics then move up to CGI not the other way around. I truly respect those who spend their time working with Computer Generated Images I have tried it myself and it was extremely complicated. When learning any kind of skill you have to be able to do the simple stuff before you can do the harder stuff. If you can do them both great you should use it in your film. I think whenever you make something you should try and achieve the highest level of excellence you can because you are stamping your name and reputation onto it. That's all I have to say.
Posted: Mon, 2nd May 2005, 7:31am

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Redhawksrymmer

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I need to learn 3DS Max.
Posted: Mon, 2nd May 2005, 8:04am

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Bryce007

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Rawree wrote:

AcjPictures wrote:

Just my $.02 I'd suggest shooting the footage with a better camera before adding in cgi. It really degrades the film when you have an amazing effect placed on poorly shot video.
I disagree. Badly filmed footage often allows you to have the most convincing CGI: Shakey cameras and Noise on the picture, when matched properly really do look much better than locked down, perfectly clean footage (whoo how exciting), the harder it looks to match, the more convincing it is when done properly.
I disagree entirely. Badly filmed footage isn't good period. Purposely motion jarred/video noised footage done in post is good. I definately Dont reccomend shooting shaky video then adding CG, as it makes it VERY hard to look good. Instead, a beginner would be better off using static shots shot from a tripod, then adding the effects, then adding shake/noise/ jerky movement in post with either a moving path or with the wiggler in AE. faking "blindcam" is far easier than framematching a CG element.

Also, poser 6's firefly renderer is fairly advanced, so it theres a possibility it either has is automatically enabled, or can be.
Posted: Mon, 2nd May 2005, 9:41am

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shadu

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The render system in poser 6 is much better than the one in poser 5?

After some search i tried to find "maximum pose" for transfering poser animation in 3D MAX (for sing vray by exemple). Butcan't find it anymore. The compagny seem to have disapear from the WEB. All the link are dead.

Shadu
Posted: Mon, 2nd May 2005, 9:53am

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Rawree

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Rating: +1

Bryce, I think the best way to go about adding CGI is to film as if the CGI is real and already there - if you would use a handheld cam if it was a real actor, in an action scene for example, then do the same for the CGI character.

In a way CGI is a bit like magic: A beginner will start of with simple tricks which can easily be recognised as an illusion in the same way that the CGI artist will use locked off camera shots with no interaction. In order to fool the audience into thinking their trick is "real magic", the magician will put obsticals and challenges in their way which at first would make the trick seem impossible (and therefore the only explaination is that it must be magic) - in the same way, if it looks impossible to fake (due to shakey cameras, grainy footage etc) then the ausience are likely to think "hey maybe this is real after all"

Of course it goes without saying that this only applies to good CGI, even it it's well matched to the camera movement and grain, if it's lit badly or textured badly the illuision is destroyed.
Posted: Mon, 2nd May 2005, 4:07pm

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Vault FX

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Hi, I just thought i would post something i created in 10mins, it is only a simple table that i modeled, it isn't very detailed but i can work on that i was just mainly trying to work on the lighting to see if i can get it to match, or as close to it as possible.



What do you think? smile

Also bare in mind that i created this in Cinema 4D 6 CE+

dalder
Posted: Mon, 2nd May 2005, 4:14pm

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Rawree

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It's looking pretty good Dalder, however the way I understand it is that underneath the table should still have a slight shadow due to light being unidirectional - A good example is to look at a parked car, it's darker underneath the car even when the sun isn't directly overhead. Do a search for Ambient Occlusion (Damn, I'm beginning to sound like Billy now! wink )
Posted: Mon, 2nd May 2005, 4:22pm

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shadu

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Very well made Dalder. Bravo.

I hope some day be able to do good CGI. For the moment, i only do the VFX for our film but i must explore all the "computer" possibility in this area and the CGI is a part of it. So i make some try.

Shadu
Posted: Mon, 2nd May 2005, 5:25pm

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billy3d

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Rawree wrote:

Do a search for Ambient Occlusion (Damn, I'm beginning to sound like Billy now! wink )
MWHAHAHAHAAH!

READ UP!
I spent like a month just trying to find out what exactly ambient occlusion is and the various menthods to fake ambient occlusion or actually create an ambient occlusion pass.

http://www-viz.tamu.edu/students/bmoyer/617/ambocc/

http://www.andrew-whitehurst.net/amb_occlude.html

http://everflow.com/support/tutorials/AO/Everflow_AmbientOcclusion1.html
Posted: Mon, 2nd May 2005, 7:00pm

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Vault FX

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Hi, I have just done another test, it isn't as bright as the first one, but i think it still works smile I found an ambient occulusion plugin for C4D which i have used on this pic.



What do you think?

dalder
Posted: Mon, 2nd May 2005, 7:03pm

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Klut

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hehe, I first though it was real, till I saw the other one.
Posted: Mon, 2nd May 2005, 7:07pm

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Vault FX

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Klut - Which one did you think was real, the first one or the second? smile If you thought that was real, i am really happy that you did smile it then makes me feel that i am getting the hang of 3D and getting better at it smile

Hope this makes sense

Thanks for the feedback

dalder
Posted: Mon, 2nd May 2005, 7:09pm

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Klut

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The last one looked very real to me.

And yes, you are getting really good.
Posted: Mon, 2nd May 2005, 7:11pm

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Vault FX

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Klut - I'm glad you like it, and i am really glad that you think it is real, obviously i am getting the hang of 3D, lol, which i am glad about, lol smile

Thanks for the feddback

dalder
Posted: Mon, 2nd May 2005, 9:06pm

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Rawree

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It looks pretty good but there is one thing:

You need to model the edge of the pavement as, at the moment, the shadow goes right across it as if the road and pavement are on the same level. You have to model stuff like the pavement just in case the shadow goes over it (which it does) - the same would be true of the wall:

Ah the universally loved Teapot.
Posted: Mon, 2nd May 2005, 10:31pm

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Vault FX

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Rawree - WOW, that really looks god smile, just a question and sorry to sound stupid, but how would i go about modeling the pavement and wall, from a still image and still making it look natural & real?

Thanks for the tips smile

dalder
Posted: Mon, 2nd May 2005, 10:38pm

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Rawree

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Well in Max for the wall I basically just made a box the same shape and in the same position as the wall and then applied a Matte/Shadow material to it which means that the box itself is invisible but any shadows cast on it can still be seen (I'm not sure if C4D has something similar). If not then I'm sure you could just use a white box to have the shadow on and then combine the "clean" picture and the shadow in Photoshop by removing the white (with one of the overlay modes I imagine).

Basically it's the same process as making the ground plane, just sometimes it takes more complex geometry.

Like I said before, the more interaction with the "real world" the more believeable the effect is.
Posted: Mon, 2nd May 2005, 10:52pm

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Pooky

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That floating teapot is terrifying.

Does HDR have anything to do with ambient occlusion?
Posted: Mon, 2nd May 2005, 11:07pm

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shadu

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Did you render the shadow in the same picture than the teapot or did you made a other picture with it? I ask that because a saw a tutorial where they render the CGI then the shadow of it before merging them togeter.

Shadu
Posted: Mon, 2nd May 2005, 11:46pm

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Rawree

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Pooky:
Ambient Occlusion and HDRI are 2 different things, I won't give an explaination because they're both pretty complex things but it'd be worth doing some research on them.

Shadu: That render is straight out of Max, no combining or anything as I find that the GI gives it a good enough look without faking Ambient Occlusion, the only alterations. Usually I would do any masking in Chromanator or Photoshop but as this was just a quick thing I used geometry to mask the shadow behind the table.
Posted: Mon, 2nd May 2005, 11:55pm

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shadu

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Thanks Rawree.

I find this: http://www.rethinkfx.com/tutorials/compmax.htm

I think it a good start do understand some principe. No?

Shadu
Posted: Tue, 3rd May 2005, 12:01am

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Rawree

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shadu wrote:

Thanks Rawree.

I find this: http://www.rethinkfx.com/tutorials/compmax.htm

I think it a good start do understand some principe. No?

Shadu
Glad I could be of some help.

As well as the one you found there's some stuff here about compositing 3D elements that you may find useful.
Posted: Tue, 3rd May 2005, 12:05am

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Serpent

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Cinema 4d does have that, but it is much more complicated than just applying something. Much has to be done.
Posted: Tue, 3rd May 2005, 7:35am

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Vault FX

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Hi, After a little bit of playing around with Cinema 4D i managed to get it to work smile I know it isn't perfect & that there are still things that need to be tweaked, but i think it still looks good smile



What do you think?

dalder
Posted: Tue, 3rd May 2005, 9:28am

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shadu

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Too much? The shadow seem a little strange.

Shadu
Posted: Tue, 3rd May 2005, 10:46am

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silencer

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It looks good but the legs of the bench and the shadows don't looks right i think the shadow should touch the corners of the legs and the part where the shadow hits the curb is a little off, i've been messing with this pic too and added a car down the street but i have no where to host it lol Hey it could be fun for people to add things to pics and others to guess what was added maybe a running thing smile

Just a thought wink
Posted: Tue, 3rd May 2005, 10:56am

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Vault FX

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silencer - send the pic to me and i can upload it for you smile send the pic to

general@firelightmovies.co.uk

dalder smile
Posted: Tue, 3rd May 2005, 6:35pm

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silencer

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Dalder that email got sent back to me sad is it the correct email?
Posted: Tue, 3rd May 2005, 7:53pm

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Landon

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billy3d wrote:

Rawree wrote:

Do a search for Ambient Occlusion (Damn, I'm beginning to sound like Billy now! wink )
MWHAHAHAHAAH!

READ UP!
I spent like a month just trying to find out what exactly ambient occlusion is and the various menthods to fake ambient occlusion or actually create an ambient occlusion pass.

http://www-viz.tamu.edu/students/bmoyer/617/ambocc/

http://www.andrew-whitehurst.net/amb_occlude.html

http://everflow.com/support/tutorials/AO/Everflow_AmbientOcclusion1.html
Oh, come on billy! Anyone with basic knowledge of 3D knows what ambient Acclusion is! I use it on every single on of my renders to some extent.

Looks okay but the edges on the place where the shadow goes up is really sharp, not smooth, try subdivision surfacing. the wood texture need a lot of work. Is it procedral? Try UV mapping an image and bump map it. Also, the benches edges are too sharp. You should bevel it (but I'm not sure how to do it in C4D).

-Landon
Posted: Wed, 4th May 2005, 7:40am

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Vault FX

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Hi, here is another render smile i have made some changes that were mentioned above smile i am in the process of sorting the shadow out so that it is not as sharp:)



What do you think?

dalder
Posted: Wed, 4th May 2005, 7:43am

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Rawree

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Chamfer the edge of the pavement a bit so it's not such a sharp corner on the shadow, otherwise it's looking pretty good.