# How do they put CGI effects into film? **URL:** \ **Category:** Factual Questions\ **Created:** [July 28, 2009, 1:25pm UTC](https://boards.straightdope.com/t/how-do-they-put-cgi-effects-into-film/504545 "2009-07-28T13:25:57Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![No\_Wikipedia\_Cites](https://avatars.discourse-cdn.com/v4/letter/n/94ad74/32.png) [@No\_Wikipedia\_Cites](https://boards.straightdope.com/u/No_Wikipedia_Cites)\ **Post date:** [July 28, 2009, 1:25pm UTC](https://boards.straightdope.com/t/how-do-they-put-cgi-effects-into-film/504545/1 "2009-07-28T13:25:57Z")
Ok, I know that Industrial Light & Magic are the experts on special effects. And Computer-based “CGI” has helped made movies with top notch special effects. But how exactly do they connect the ‘computer’ generated effects into the 35mm film itself? ---
**Author:** ![coremelt](https://avatars.discourse-cdn.com/v4/letter/c/4491bb/32.png) [@coremelt](https://boards.straightdope.com/u/coremelt)\ **Post date:** [July 28, 2009, 1:31pm UTC](https://boards.straightdope.com/t/how-do-they-put-cgi-effects-into-film/504545/2 "2009-07-28T13:31:50Z")
feature film compositor speaking here… they scan the film digitally using a film recorder… rooms full of 2d digital effects artists (compositors) and 3d artists go to work to match the effects with the shot footage. They produce finished versions of the shots as image files, then they use a laser film recorder to take a digital negative file and record that back to 35 mm film. there is an entire black art in doing the color matching between original 35 mm film, all the effects and then matching it back to produce a finished 35 mm print that matches the original, apart from the adding of the effects. The standard text on this is Ron Brinkmann, “the art and science of digital compositing” > **[The Art and Science of Digital Compositing (The Morgan Kaufmann Series in...](https://www.amazon.com/Science-Compositing-Kaufmann-Computer-Graphics/dp/0121339602)** > > The Art and Science of Digital Compositing (The Morgan Kaufmann Series in Computer Graphics) \[Brinkmann, Ron\] on Amazon.com. \*FREE\* shipping on qualifying offers. The Art and Science of Digital Compositing (The Morgan Kaufmann Series in Computer... of course that was the “old method”… now that there is commonly color grading done digitally as well it’s even more complicated… read up on “digital intermediate” for more info: > **[Digital intermediate](https://en.wikipedia.org/wiki/Digital_intermediate)** > > Digital intermediate (DI) is a motion picture finishing process which classically involves digitizing a motion picture and manipulating the color and other image characteristics. > A digital intermediate often replaces or augments the photochemical timing process and is usually the final creative adjustment to a movie before distribution in theaters. It is distinguished from the telecine process in which film is scanned and color is manipulated early in the process to facilitate editing. However t... ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [July 28, 2009, 1:34pm UTC](https://boards.straightdope.com/t/how-do-they-put-cgi-effects-into-film/504545/3 "2009-07-28T13:34:13Z")
If the live-action is actually shot on film (the industry is moving to digital cameras), the film is scanned and then the scene is composited in a computer. The final version is then output with a very high resolution film recorder. Here’s Wikipedia on CGI:[Computer-generated imagery - Wikipedia](http://en.wikipedia.org/wiki/Computer-generated_imagery) Here’s some information on film out: [Film-out - Wikipedia](http://en.wikipedia.org/wiki/Film-out) ---
**Author:** ![GuanoLad](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/guanolad/32/42_2.png) [@GuanoLad](https://boards.straightdope.com/u/GuanoLad)\ **Post date:** [July 28, 2009, 2:03pm UTC](https://boards.straightdope.com/t/how-do-they-put-cgi-effects-into-film/504545/4 "2009-07-28T14:03:48Z")
> [@coremelt](#): > > feature film compositor speaking here… The biggest stuff I’ve ever worked on is only 1080p HD, I’ve never done proper film. What kind of resolution do you work in? 2k? 4k? What kind of challenges are there to making digital elements look like film elements? ---
**Author:** ![Bijou\_Drains](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bijou_drains/32/2814_2.png) [@Bijou\_Drains](https://boards.straightdope.com/u/Bijou_Drains)\ **Post date:** [July 28, 2009, 4:16pm UTC](https://boards.straightdope.com/t/how-do-they-put-cgi-effects-into-film/504545/5 "2009-07-28T16:16:09Z")
Trivia , in early cuts of Star Wars the CGI battle scenes were not ready yet so Lucas plugged in WW II and WW I fighter battles on film. ---
**Author:** ![gonzoron](https://avatars.discourse-cdn.com/v4/letter/g/a6a055/32.png) [@gonzoron](https://boards.straightdope.com/u/gonzoron)\ **Post date:** [July 28, 2009, 4:49pm UTC](https://boards.straightdope.com/t/how-do-they-put-cgi-effects-into-film/504545/6 "2009-07-28T16:49:15Z")
> [@Bijou\_Drains](#): > > Trivia , in early cuts of Star Wars the CGI battle scenes were not ready yet so Lucas plugged in WW II and WW I fighter battles on film. True, except that the original Star Wars effects weren’t CGI, they were models filmed with motion controlled cameras. CGI didn’t exist as we know it back then. ---
**Author:** ![Bijou\_Drains](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bijou_drains/32/2814_2.png) [@Bijou\_Drains](https://boards.straightdope.com/u/Bijou_Drains)\ **Post date:** [July 28, 2009, 5:06pm UTC](https://boards.straightdope.com/t/how-do-they-put-cgi-effects-into-film/504545/7 "2009-07-28T17:06:20Z")
Yes, forgot about that. I think they had some CGI by the time of Empire Strikes back did they not? ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [July 28, 2009, 5:11pm UTC](https://boards.straightdope.com/t/how-do-they-put-cgi-effects-into-film/504545/8 "2009-07-28T17:11:36Z")
The only CGI they had at that time was the things that looked blatantly like computer graphics, like the targeting computer in the trench and the Death Star plans. ---
**Author:** ![jjimm](https://avatars.discourse-cdn.com/v4/letter/j/ba8739/32.png) [@jjimm](https://boards.straightdope.com/u/jjimm)\ **Post date:** [July 28, 2009, 5:15pm UTC](https://boards.straightdope.com/t/how-do-they-put-cgi-effects-into-film/504545/9 "2009-07-28T17:15:08Z")
> [@coremelt](#): > > there is an entire black art in doing the color matching between original 35 mm film, all the effects and then matching it back to produce a finished 35 mm print that matches the original, apart from the adding of the effects. Does that explain why a lot of CGI looks ‘dusty’? Especially the older stuff is. E.g. Jurassic Park seemed astonishing at the time, but looking at it now, the lighting and colors on the CGI look kinda pastel compared to the live action. Rampant speculation: maybe that’ll be the case with stuff being made now - looks great at the moment but compared to something else in 10 years’ time it will look a bit shonky. ---
**Author:** ![ianzin](https://avatars.discourse-cdn.com/v4/letter/i/ed655f/32.png) [@ianzin](https://boards.straightdope.com/u/ianzin)\ **Post date:** [July 28, 2009, 5:49pm UTC](https://boards.straightdope.com/t/how-do-they-put-cgi-effects-into-film/504545/10 "2009-07-28T17:49:47Z")
> [@jjimm](#): > > Especially the older stuff is. E.g. Jurassic Park seemed astonishing at the time Even so, the special effects were so good I could barely tell the fake dinsosaurs from the real ones. ---
**Author:** ![garygnu](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/garygnu/32/2924_2.png) [@garygnu](https://boards.straightdope.com/u/garygnu)\ **Post date:** [July 28, 2009, 6:11pm UTC](https://boards.straightdope.com/t/how-do-they-put-cgi-effects-into-film/504545/11 "2009-07-28T18:11:54Z")
> [@ianzin](#): > > Even so, the special effects were so good I could barely tell the fake dinsosaurs from the real ones. You’re probably being facetious, but for _Jurassic Park_ they did use plenty of stop-motion miniatures and full-sized animatronic puppets. ---
**Author:** ![Bijou\_Drains](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bijou_drains/32/2814_2.png) [@Bijou\_Drains](https://boards.straightdope.com/u/Bijou_Drains)\ **Post date:** [July 28, 2009, 6:30pm UTC](https://boards.straightdope.com/t/how-do-they-put-cgi-effects-into-film/504545/12 "2009-07-28T18:30:33Z")
The T-Rex in scenes up close to the actors was mechanical. Most of the other dinos were CGI. ---
**Author:** ![JSexton](https://avatars.discourse-cdn.com/v4/letter/j/96bed5/32.png) [@JSexton](https://boards.straightdope.com/u/JSexton)\ **Post date:** [July 28, 2009, 6:33pm UTC](https://boards.straightdope.com/t/how-do-they-put-cgi-effects-into-film/504545/13 "2009-07-28T18:33:32Z")
> [@Bijou\_Drains](#): > > Trivia , in early cuts of Star Wars the CGI battle scenes were not ready yet so Lucas plugged in WW II and WW I fighter battles on film. Goes back earlier than that. Instead of storyboarding the fighter battles, he cut together the WWII footage and used those shots as the basis for the action, angle for angle. ---
**Author:** ![AK84](https://avatars.discourse-cdn.com/v4/letter/a/85e7bf/32.png) [@AK84](https://boards.straightdope.com/u/AK84)\ **Post date:** [July 28, 2009, 7:03pm UTC](https://boards.straightdope.com/t/how-do-they-put-cgi-effects-into-film/504545/14 "2009-07-28T19:03:57Z")
Related question, what do they do in lieu of the CGI action, footage, character when shooting (which I presume is done before the CGI is added)? ---
**Author:** ![msmith537](https://avatars.discourse-cdn.com/v4/letter/m/d9b06d/32.png) [@msmith537](https://boards.straightdope.com/u/msmith537)\ **Post date:** [July 28, 2009, 7:10pm UTC](https://boards.straightdope.com/t/how-do-they-put-cgi-effects-into-film/504545/15 "2009-07-28T19:10:46Z")
> [@AK84](#): > > Related question, what do they do in lieu of the CGI action, footage, character when shooting (which I presume is done before the CGI is added)? Is your question what do the live actors use as references when filming the scene? From what I’ve seen in “making of” shows, instead of a CGI dinosaur, they might use a guy waving a stick with a tennis ball at the end of it to show the actors where the T-Rex is supposed to be. The may also interact with physical props that are painted blue / green so as not to be picked up by the camera. ---
**Author:** ![Bijou\_Drains](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bijou_drains/32/2814_2.png) [@Bijou\_Drains](https://boards.straightdope.com/u/Bijou_Drains)\ **Post date:** [July 28, 2009, 7:18pm UTC](https://boards.straightdope.com/t/how-do-they-put-cgi-effects-into-film/504545/16 "2009-07-28T19:18:08Z")
In some cases where there is a total CGI character they just have a real person stand there next to the real actors , the actors speak to the real person who is later replaced by the CGI character. ---
**Author:** ![filmyak](https://avatars.discourse-cdn.com/v4/letter/f/94ad74/32.png) [@filmyak](https://boards.straightdope.com/u/filmyak)\ **Post date:** [July 28, 2009, 7:42pm UTC](https://boards.straightdope.com/t/how-do-they-put-cgi-effects-into-film/504545/17 "2009-07-28T19:42:52Z")
FYI before CGI most “modern” film effects used opticals and mattes. Miniatures were shot, mattes were created (black spaces on the film which, because they were black, weren’t exposed at all), then those areas were later exposed with the effects footage in where the black holes were. That’s a very simplified version. Also things like Ghostbuster rays were hand drawn, frame by frame. If you want some in depth stuff, pick up an issue of Cinefx. Great industry magazine that goes into uber-detail of whatever movies they cover. Meant for folks who do fx for a living so you’ll learn the real deal. PS - I worked with a guy who worked on the Spider-Man movies, and he made an interesting point. Effects in the middle of most movies tend to be the best. At the start of the film, they’re still figuring out techniques for the specific movie (how do we make Spidey’s movement and clothing look real). By the middle, they’ve got it fairly down pat. By the end of the film, they’re behind schedule and struggling to catch up. (Much of the effects work is done sequentially more or less, as opposed to shooting which can be done in any order at all.) ---
**Author:** ![GuanoLad](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/guanolad/32/42_2.png) [@GuanoLad](https://boards.straightdope.com/u/GuanoLad)\ **Post date:** [July 28, 2009, 11:49pm UTC](https://boards.straightdope.com/t/how-do-they-put-cgi-effects-into-film/504545/18 "2009-07-28T23:49:01Z")
> [@filmyak](#): > > At the start of the film, they’re still figuring out techniques for the specific movie (how do we make Spidey’s movement and clothing look real). By the middle, they’ve got it fairly down pat. By the end of the film, they’re behind schedule and struggling to catch up. Though this part is true in terms of post-production schedule… > [@filmyak](#): > > (Much of the effects work is done sequentially more or less, as opposed to shooting which can be done in any order at all.) …this part is not true. They will spend a lot of time on R&D to perfect new techniques (like creating Gollum, for example), then apply it to the shots throughout the film, anywhere from beginning to end. You’ll notice that some of the best shots of Gollum are in sporadically placed scenes throughout the film, sometimes very near less convincing looking versions. ---
**Author:** ![GuanoLad](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/guanolad/32/42_2.png) [@GuanoLad](https://boards.straightdope.com/u/GuanoLad)\ **Post date:** [July 28, 2009, 11:59pm UTC](https://boards.straightdope.com/t/how-do-they-put-cgi-effects-into-film/504545/19 "2009-07-28T23:59:33Z")
> [@msmith537](#): > > The may also interact with physical props that are painted blue / green so as not to be picked up by the camera. Greenscreen and bluescreen is picked up by the camera. But they can get “[keyed out](http://en.wikipedia.org/wiki/Chroma_key)” in post production. That is, they are turned transparent so things can be placed behind or painted over. They also use those colours as guides for foreground compositing, as it’s easier to see a bright green thing to fix than it is something regular coloured. > [@garygnu](#): > > You’re probably being facetious, but for _Jurassic Park_ they did use plenty of stop-motion miniatures and full-sized animatronic puppets. There was no stop motion in _Jurassic Park_. However, it was a transitionary period between stop motion and CG animation, so they created something they called a [Digital Input Device](http://graphics.pixar.com/library/DinoInputDevice/) (though they called it the _Dinosaur Input Device_ when they invented it), which allowed the stop motion animators to move a simplified model attached to a computer, and use it sort of like a 3D mouse to animate the CG dinosaurs in a way familiar to them. This method isn’t necessary anymore; stop motion art is such a rare skill these days, most are adept at using both disciplines. ---
**Author:** ![scm1001](https://avatars.discourse-cdn.com/v4/letter/s/c4cdca/32.png) [@scm1001](https://boards.straightdope.com/u/scm1001)\ **Post date:** [July 29, 2009, 12:31am UTC](https://boards.straightdope.com/t/how-do-they-put-cgi-effects-into-film/504545/20 "2009-07-29T00:31:27Z")
Are main feature films being shot now in digital rather than film? That would seem to make things easier all round? [Next page](https://boards.straightdope.com/t/how-do-they-put-cgi-effects-into-film/504545.md?page=2)