How to Not ‘Cross The Line’
In storyboarding there's something that's known as the 180 degree rule; it refers
to theAction Line, or the Camera Line, or the Stage Line. It’s an invisible line that runs
throughthe shot to maintain screen direction and continuity. Most times this line is theline of sight
between two characters and is part of a semi-circular area where the camera canbeplaced to maintain continuity.
This axis line is an imaginary line drawn down the center of the action of a scene.
In many live-action film making books it looks something like this.

Draw a line through the center of the 360 degree circle that orbits around yourcharacters.

Now you’ve got that 180 degree range once you’ve establish the first shot of
which side
Of the semi-circle you’ll be on.
The principle is that once you choose where that line will be, you can put yourcamera
along any part of that 180 half circle and the scene will work (direction-wise).
Like this.

If you place your camera suddenly on the other side of that line, your direction
gets screwed up.

Someone or something is now facing the wrong way. This can really disorient theaudience.
Rule one of visual storytelling: don’t disorient your audience.
Especially when you are planning your scenes for animated series or films.
In cartoons we work on two-dimensional paper or a computer screen.
So think about it in our wonderful two-dimensional world.
On paper. On a screen. Even you live-action gurus.
It just might make your life a little easier when thinking about where
The camera is within the three dimensional space.

Instead of the imaginary line and the little cameras and the half circle,
just think about the frame (or the storyboard panel…same thing).
Draw a line down the middle of the frame and that frame has two sides.

A left side and a right side. When storyboarding, always think of the left andright of the frame, not the ‘left of this character’ or the ‘right of that character’.
Just the left side of the frame and the right side of the frame. That’s it.
Now we have our two folks at the table. The dude is on the left, the lady is on theright.

Keep them there.
Where does the dude have to look to see the lady?

Right side.
Where does the lady have to look to see the dude?

Left side.

That’s it.
Keep them always facing that other side (and keep them on their own sides)
and you will never cross the line.
I know it sounds stupidly simple. But people screw it up all the time.
When they start using different shots and angles, it can slip away fromthem for a shot or two (or seven).
It doesn’t just work with people in a shot. It can be the guy and his TV.

The dog and a tree.

The child and the moon.

Just keep asking yourself the questions.
Which side did you establish the TV, the tree, the moon on?
Then which side of the frame must the guy, the dog, the child face to see it?

Then face them that way and keep the person/object
on their own side.
Now things can get a lot more complicated. Add in a few more people.
Have them all sitting at the dinner table. Have them enter and exit.
You can change the line and establish new ones.
Then you follow the same rules.
Remember you have to learn the rules before you can break ‘em.

How to ‘Cross The Line’
With some directors, this is a hard and fast rule that is not broken; with others,
it is broken liberally. Most directors fall somewhere in the middle. The mostimportant thing (at least to me) is knowing HOW and WHY one crosses the line.
To me the 180 is not really a rule; it is a suggestion. Most of the time we arewithin thecomfortable confines of the 180 semi-circle, but every now and then, to break up
what
can turn into monotony and also to generate interest, we go over.
It's up to us to use all the tools available to make our scenes and shots
interesting.
Just because a character is on the left side of the screen doesn't mean they havetobe there for the whole scene; or because a car is moving from left to right doesn'tmean it has to be moving left to right in every shot, especially in action scenes.
Take a look at your favorite films and see if and when the director goes over theline;
look at it and ask yourself HOW and WHY the director did it.
Some suggestions on how to go over the line:
1. Lead the viewer's eye to the part of the screen where you want them to lookwhen you cut over the 180.
2. Create a big enough change in the shot that the characters don't jump or pop.
3. Cut away to a third character or object or action
4. Cut to a neutral angle (an ON AXIS shot, where the camera is ON the line ofaction)
5. Move the camera over the line creating a new line.
6. Just do it - to elicit a reaction from the viewer, a good example is the openingof ‘The Insider’ by Michael Mann.