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TUTORIAL: Animation: Artificial camera shake

Posted: Tue, 18th May 2004, 2:27pm

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Simon K Jones

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Chromanator Tutorials: Animation

Artificial camera shake

There's always been an inherent problem with composited special effects, from the very earliest days of cinema until only very recently: to composite an effect convincingly, it needs to match the movement of the live camera.

This is far easier said than done, which is why any effects shot prior to the late 1970s will be almost entirely static. Check out any of the Ray Harryhousen stop-motion classics, for example – the effects shots will likely be shot with locked down, stationary cameras. Back in the days of optical compositing this was the only way, as matching camera moves optically would have been horrendously difficult.

The advent of digital compositing in the late 80s and 90s started to free the camera considerably.

Wobbly cameras
A locked down, immobile camera makes compositing very, very easy. However, it can often lead to a less-than-interesting shot, or one that is at odds with the style of the rest of the film. However, introducing a wide range of movement to the camera can pose many problems, making tracking a very difficult process.

The solution is to keep camera movement steady and easy to track, and then enhance the motion using Chromanator. For this example I'll use the same clip that was used for the Artificial Movement tutorial.

Zoom and move
I want to have the camera shake when the fireball races past the camera, and again when it impacts with the ground. In order to give myself enough space to manoeuvre, first I need to enlarge the image a little to provide space around the edges.

  • If the clip is not enlarged, when I add the camera shake the edges of the frame will become visible, breaking the illusion.

Using the right mouse button on the origin (centre) quad point, I can quickly drag the mouse to enlarge the clip. A scale of 1.08 should be sufficient for this situation.

You should enlarge the clip as little as possible. If you zoom in too much, the image will become pixellated and the post-production fiddling will become obvious.

  • The amount of enlargement you can get away with will depend on the quality of the source footage.

At appropriate points I can now move the quad around to reposition the frame, thus simulating camera shake. By moving the quad in opposing directions on each frame, the effect can prove very convincing.

  • Make sure the white quad borders stay outside of the blue frame borders, or the edges of the frame will become visible when you render.
  • Rotation can also add to the effect.
  • Too much camera shake can often look fake – bear in mind you're trying to create a ‘real' effect.

The finishing blur
An extra touch that can make the artificial camera shake more convincing is to add some motion blur. A violent camera shake is likely to leave the image somewhat blurred, so if the frame is still crystal clear the audience may subconsciously register that something is wrong.

The Blur Angle tool can be found in the Effects toolset and is very useful for creating the required blur. The rotation wheel determines the angle of the blur.

Make sure the yellow dot points in the direction you want the blur to go – ie, the opposite direction to the movement itself.

  • Make sure you don't overdo the blur. Try to compare it to some real blurred footage.

Another tip to remember is that if you are working on a widescreen project, if you film it in 4:3 and crop it later, you can use the extra screen area to create a wider range of movement.

Click here to watch an example clip.

Posted: Wed, 19th May 2004, 11:34am

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Brettsta

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In this clip is the ball of fire and the backround in one clip, or do you only shake the back clip (with the guy reacting)
Posted: Wed, 19th May 2004, 11:41am

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Simon K Jones

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Ah, good question, I should have mentioned that.

First I composited the effects, and rendered them out. Then I performed the camera shake on the finished, rendered composite. That way you can ensure that everything moves together as it should, and don't have to worry about shaking each individual layer.