I laugh when people say that artists can't do math, because there's a lot of math required for a good painting. I've been working on the composition for this new narrative painting and I've finally got the composition down. In my previous post, I had a really rough composition, but it's now refined and the shapes are all worked out.
A really good tool for composition and proportion is tracing paper. I traced the pose from a detailed study I did and then was able to move it around in the composition until I found a pleasing pose. Then I taped down the tracing paper and drew a proportional rectangle around the composition. All of this is done in pencil because a lot of erasing is involved.
I also always have a sense of life-sized scale in my mind. I keep this in mind because I want my canvas to be roughly 2/3 life size. I measured my dog, Maea, and found out she's about 20" long when in the pose I need. So I want her to be about 13" in scale for the canvas. I usually measure in centimeters and then convert to inches because centimeters are more accurate with my small drawing.
The formula I use for figuring out the final size is: A/B = C/D
In this case: A is the width of my sketch (2.95")
B is the height of my sketch (3.54")
C is the width of my final canvas
D is the height of my final canvas
This is where I keep the models size in my mind to figure out a pleasing canvas. Since she's a small dog, I don't want a huge canvas. Because C and D are my unknowns, I used large rulers and laid out a width that would give me enough room for the dog and surrounding. I decided on a 24" width. Because I know my variable, C, then I can use the formula to find out D
2.95(A) 24(C) 3.54 (B) X 24 (C) = 84.96
--------- = ---------- 84.96 / 2.95 (C) = 28.8 (D)
The equation of (B X C) will give you a number that, when divided by C will give you D. It's a really simple equation that I use all the time.
After I have the final canvas size, I always lay it out on the floor to see if I think it looks good. I always end up making small changes, even after all that math. I ended up rounding my canvas height to 30" because it's a more pleasing rectangle.
It's more work and it's always worth it.