3 Cost Effective CGI Techniques

Guest post by Hugh Hancock of Strange Company.



When you hear the phrase ‘special effects’ as applied to your films, you probably think, ‘we can’t afford that’. Or alternatively, maybe you think, ‘we don’t need that’.

In 2015, both of those thoughts are outdated.

The price of visual effects is in free-fall – so much so that I recently abandoned ‘Machinima’, the indie animated medium I pioneered for the world of Real Filmmaking. I had previously avoided live-action film because it came with so many limitations, but we’ve hit a tipping point on that, and many things I would have thought impossible to do on an indie budget are now more than doable.

And at the same time, independent filmmakers outside the usual scifi-fantasy-action-horror genres are starting to realise that VFX ain’t just for the genre guys and girls any more. Almost every commercial movie and TV show uses subtle VFX these days. And you, too, can use them to enhance production values, improve storytelling and create scenes you couldn’t create any other way.

So, I think that pretty much every filmmaker should be considering how she or he can use CGI to enhance their production. Here are three ways that you can affordably use CGI elements to enhance your films:

Set Extension And Replacement

With the advent of sophisticated tracking tools, you can easily modify your set in post-production.

Set modification is comparatively simple. For each shot where the element you want to modify appears, you’ll simply track the camera (a function that After Effects now provides, although arguably external tools like Syntheyes are still better), then create a 3D element with the appearance you need. That element would usually be created in Photoshop.

Here’s a simple example of going through the whole process in After Effects to remove an object from a complex moving shot:



So what can you do with this?



• You can remove or change inconvenient elements in a shot. Not only does that let you ‘fix it in post’, but with production planning it can save you a fortune. For example, you can remove modern-day elements from a historical shot, change a sign on a building (up to and including skyscrapers), or perfect your framing by taking out elements you don’t need.

• You can create set elements that you don’t have or can’t afford, from jeeps to castles to entire cities (in the background). For example, here’s Star Wars director Gareth Edwards demonstrating how he added Constantinople to the skyline of Attila The Hun. And here’s how this effect pretty much makes Game Of Thrones possible.

2. Greenscreen

Greenscreen has been around forever, but until comparatively recently it’s been a complete PITA to use and usually looked terrible unless you had an army of assistants to clean up your footage.

But thanks to the ongoing march of technology in the VFX world, these days keying tools are (comparatively) easy to use. They’re also much, much faster than they used to be; Premiere’s ‘Ultra Key’ is particularly quick, and it’s now available in After Effects too.

Here’s an example of what you can do as a rank amateur. This was literally the first time I’d touched modern greenscreen tools, and the tech side of the process took me less than a day:

So what can you do with greenscreen? The obvious thought is to put people in fantastic, historical or sci-fi sets, as above – and of course you can do that. But there’s much more, too. For example, here’s Mr Gareth Edwards again (who was one of the big pioneers of using this kind of technology outside Hollywood) turning a single energetic actor into an entire army:

At the less dramatic end, greenscreen can save your ass from expensive location pickup shots. I recently shot an action short in an abandoned factory, which was due to be entirely renovated the day after shooting. On the day, one actress couldn’t make the shoot. Disaster? Nope. We’re just picking up her shots on a greenscreen, then matching them into footage we shot on the day as background plates.

What else could you do with greenscreen on your production?

• You can completely re-locate your footage. TV shows do this all the time. Watch Gossip Girl’s interiors, frequently shot against a gorgeous New York backdrop, or check out these examples of studio-shot footage plus greenscreen. Again, people tend to remember the really spectacular uses of greenscreen, but just being able to shoot a sequence in your garage and have it look like it’s on a glitzy terrace, for example, can really change the possibilities of your film.

• You can place your characters in harm’s way without doing the same with your actors. Stu Maschwitz’s DV Rebel’s Guide has hundreds of examples of this sort of thing. But, in short, the process is: shoot dangerous thing, shoot actor against green, key out background, composite and match lighting. All the tension, none of the lawsuits.

3. Stock Footage Insertion

It’s tremendously easy these days to composite elements of stock footage into your shots. And this can be astonishingly powerful.

The best use of stock footage compositing I’ve seen recently was in the TV show Orphan Black. At one point, a character’s attempting to flee another character who has a gun, into a cornfield. Firing guns on set is expensive, as we all know; and in this case it wouldn’t have served the scene. Instead, they simply cut to a wide shot, then had a gunshot go off – and some birds fly up, startled by the shot.

Now, it’s possible that those were real birds. But if it was me shooting that scene, I’d definitely have just composited in the bird footage. It completes the shot, and turns a static video of a cornfield into a moment of high drama.

Here are a few ways you can use this technique, which takes minutes, to add production value or allow you to shoot scenes that otherwise wouldn’t be possible:

• The absolutely classic use for the insertion of stock footage is gunfire. Doing it well requires more than just a simple insertion of a flare, but it’s comparatively quick. Here’s a video demonstrating a single gunshot created in After Effects:

• Explosions, fire and smoke are all effective uses of a stock footage insertion, allowing you to add the kind of shots you wouldn’t believe possible on a low-ish budget. If you watch a lot of TV shows carefully, you’ll see these effects all the time. Video Copilot are the usual go-to people for this kind of effect, and the results, done well, can be very impressive:

• Subtle atmospherics can really add to production value and mood for a scene. Subtle smoke and fog, in particular, are comparatively easy to use and are very effective, and even more drastic changes like rain are also possible. Rain’s a bit of a pain in the neck to composite correctly, but it’s worth it for a wide shot.

• Finally, background elements, or even actors, are a possibility. Have a stock-element character in a police uniform walk in front of your main character, out of focus, to sell an investigation scene. You can build a crowd from a whole bunch of stock elements, given time. It won’t hold up in focus for even a minute, but it’ll work as an out-of-focus background or a quick wide. And, of course, there’s the option of adding wildlife, as mentioned above!

More Ambitious Stuff … and a few things you shouldn’t try

You can get even more ambitious if you have the time or a modest budget.

• CGI objects are much easier to sell than CGI characters. Even cars, planes or buildings are comparatively simple to build, render and make work in a shot. You’ll probably need a CGI expert or a month or so learning a CGI program to create, render and export the objects, but it’s doable on an indie budget.

• If you’re going to go for CGI-that-looks-like-CGI, energy effects are probably the easiest ones to get away with. Beams, energy blasts, eldrich portals – a bunch of additive layers and some particle effects, and you can get to the point where they don’t get in the way of the story, at least.

• It’s possible to substitute CGI for makeup to a significant extent if you only need it for a few shots. Zombie effects, glowing eyes, weird skin textures: all of those are very doable with 2015’s CGI. Here’s a great single-shot tutorial on a fairly drastic CGI makeup job.

There are a few things you probably can’t get away with, though:

• People loved my most recent short film, but the one negative comment I got was about the quality of the CGI. That’s because I’d gone for broke and included an entirely CG character as one of the two characters in a 10-minute piece. Even given I’ve been doing this for nearly 20 years, and I use the same motion capture technology as the Avengers Assemble team used, I couldn’t quite reach over the Uncanny Valley (although I have some ideas for improving in the future). For most filmmakers, CGI characters are still out of reach unless they’ll only be in a shot or two and, preferably, aren’t humanoid.

• Animals are hard. You’ll need a hand animator to do their animation, which will be really expensive, and you’ll have a lot of the same problems as you would with humanoid creatures (above). If the animal doesn’t have fur, you don’t need it for more than about ten seconds and you have some budget to burn, it’s doable. If not, avoid.

And that’s it! Have you had massive wins – or massive misses – using CGI elements in your productions? Let us know in the comments, or on Hugh’s Twitter.