Thursday, September 11, 2008

Line Weight Hierarchy

Computer drawings made with the CAD program often show the lines all the same thickness or weight. In a large or complex drawing made with uniform line weight, it can be a bit difficult to make out what’s important.

Architects learn to prioritize certain lines and give them greater weight to help the eye sort things out. This “line weight hierarchy” follows specific rules.

First, as an object gets closer to the viewer, it should be drawn with a heavier line.
Within a given form, the heaviest line should be reserved for the outer contour or silhouette (a).

The second heaviest line should be used for "plane breaks" (b)—that is, lines within the form that define the edge where two planes meet.

The finest lines belong to surface details within a given plane (c).

If you reverse those rules and put the heaviest lines in the back of the scene or on the superficial details, you can see how confusing the drawing becomes.

Thanks to Henry Sorenson for explaining this to me.

CAD drawing from Rough Rider Industries, link.


Frank said...

That's interesting.

I draw with quill pens all the time and I fine that the more uniform lines I create the better the image tends to look, but I'm more talking about calligraphy than general line weight rules...

Anyway, what makes things "come forward" or "stand out" is contrast; if you were to do the whole illustration in the same thin lineweight, then the object in the back in a thicker line, the object in the back would become the focal point...

There's a lot of theory on this stuff but you know it already.

rock on!


Jen Z said...

There are whole books written on this subject! It's an important science in the comic world - I recently read up about it -"The Art Of Comic-Book Inking"
by Gary Martin- (because I'm a horrible inker) and I was really surprised how so many inkers can interpret one pencil sketch so differently.

Unknown said...

Where do you find these rules? This is amazing, I think you have the very best collection of honest drawing methods I've read anywhere. I draw primarily with quill type pens like Frank but am getting a Wacom tablet tomorrow which is pressure sensitive. Very curious about it. It's interesting-my primary interest in line variation is it's expressive quality-I wonder if there is a natural propensity to do this? I find there is a persistent tradition from wood blocks to have heavy lines all over which is really hard to pull off and is automatically heavily stylized.

Sarah Stevenson said...

This is a very concise way of explaining it! I would have loved to get advice this succinct in my beginning drawing class in college way back when.

Erik Bongers said...

Agree with Frank.
Uniform lines can make a better looking picture, but I think this is because uniform lines make a drawing look styled. The unform lines are also sometimes called 'democracy of lines' and in the comic book world this is known as 'ligne claire' or 'clear line' style.
I think the reason why clear lines also work with a drawing is because with that style all objects are simply defined by their outline and that's very narrative and descriptive by itself. Most often when coloured, such drawings are coloured flat, that is, no shadows. Tintin is of course the most famous example of this.

I find the thicker/thinner lines technique works best when you want to 'shape weld' (to use Gurney terminology) by applying shadows and hightlights, either through color or in B/W through cross hatching.

I also agree with Jen Z.
The same pencil drawing inked by different people will show how personal a thing like inking is. In fact a viewer will quite often more easily recognize the inkers works than the pencillers work !
But I think this also shows that there is no right or wrong inking.

My own experience.
I often find myself reinking important (foreground) lines after applying color. (I apply color directly to my inked drawings)
The thin lines might have looked good enough in B/W, probably because of the 'democracy of lines applied', but once I 'shape welded' with colour, some lines just need that extra weight.

Frank said...

its so weird to me to hear people use the word "style" and "stylize" so much... I mean, everything you choose to do is style; that's what it means to design. I guess what they mean is less "naturalistic," but that's still another weird word to throw around.

Unknown said...

Um, I think I'm the only one to use the word stylized Frank and it's a way to describe traditional methods of describing something visually relying on something other than observation. Very different from style and nothing to do with naturalistic representation. What's weird about these terms?

Jose Romero said...

I looked at the pictures before reading the text and I must say that I got a better 3d feeling from the nearest box in the last drawing, with the heaviest lines in the "plane breaks"...

Erik Bongers said...

Well, there you go.
There's no right or wrong.
It might be that to some of us the thicker lines in the background represent blur as in out of focus while the thin lines in the foreground give a crisper outline and thereby attract more attention or more desire to examine the object more in detail (that would be in a real world drawing, not simple cubes of course).

Point taken that naturalistic rendering is also a form of 'style' but it just easier to talk when assuming naturalistic rendering the opposite of stylized rendering.

Frank said...

eric orchard - The reason I don't like the word "stylized" is because everything you touch should have your fingerprint on it, that is, it should be obvious that it is your creation. Talking about stylization assumes a "norm" that is non-stylized and even exist. I understand where the definitions come from, I just think they miss the point completely.


ie said...

I'm late to the discussion, but I think you're missing the point. This is the way architects do it, for maximum clarity and contrast. Artistic drawing doesn't need to follow those rules, and might want to emphasise other parts of the drawing, but it WILL be easier to understand where everything is if you do it this way.