Saturday, May 22, 2010

In which I start telling how I drew my avatar

In About my display picture, I explained what motivated me to draw my current display picture. Having decided what I wanted to draw was only half the battle: I had absolutely no idea how to draw a mouse. Ideally, I'd have a live model, but I knew my mother wasn't going to buy me an escape-happy, wall-chewing rodent just because I wanted to draw it.

I therefore went with the next best thing: look for a photograph. Most people think the only way to use a photo for drawing is to trace it and reproduce every hair, every floating dust particle, every trick of the light exactly. This becomes noticable because, well, if your model were to move, you wouldn't be able to get all those details. What I had to do, then, was use the photos to find the proportions and basic shapes that, when our brains see them, make us think, "Aah! There's a mouse in the house!"

After searching through several unsuitable pictures in the Google Images results (I needed a model facing sideways to learn the shape right) I went to Wikipedia and took the following image from there. (Girls, hold your screams)
This image was ideal for what I wanted to do because I had a mouse facing sideways and a mouse facing forward. Granted, the mouse facing sideways has his head slightly cocked to his left, and the mouse facing forward is looking a bit downards, but for what I needed, it was enough.

Finding a base shape
I started with the mouse facing left. The first impression I had was that his head formed a teardrop shape (and apparently, I'm not alone) so I decided to test that. The teardrop is not one of those common primitives/autoshapes, so I had to make one myself. A tear drop is made by taking a circle, finding two points at the same “height”, and extending them in a tangent direction. Or, for you physicists, imagine two bodies in circular motion in opposite directions (one clockwise, one counterclockwise, starting from the same point) describing the same circle, and starting from the “lowest” point in that circle. I let go of both bodies at the same y-coordinate (a coordinate above r); what trajectory do I get by the time they crash into each other?

The first challenge was finding the circle to base myself on. I put a small circle at the base of the ear, and enlarged it to reach the point where the head became fuzzy (where the fur mixed in with the background)

I next had to choose my “y-coordinate”. I made this be where my circle no longer ran along the edge of the mouse’s head.

Running the tangent worked pretty well at the beginning, but as soon as I passed the mouse’s brow, the line went way off its desired course. Something similar happened with the bottom line: it went into the mouse’s head at the chin, and then flew off radically.

Obviously the teardrop wasn’t the answer, but I had learned a couple of things. First, that mice have a small ridge at their brow, and another at their chin, after which the “slope” of the line increased. Second, that the mouse’s eye was exactly on the circle, at about the height of the ear.

Let's try that again
My second approach was to try to find a series of points where the line that describes the head changes slope (that is, if I couldn’t draw a straight line from that point to the tip of the nose, another point was needed in the middle, and I’d go and check against that). The basic idea was still the teardrop, but now instead of having the lines go off on a perfect tangent, I’d make them pass through these points.

Apart from the ones I had already discovered (the brow and the chin), there was the obvious one: the tip of the nose. The other two, however, quite astonished me. The fact that there was a small ridge between the whiskers and the eye, and not a straight line, makes sense when you think of the fact that the whiskers have to connect to something underneath the skin. But then there was the fact that from the tip of the nose to the mouth it wasn’t a straight line, either; but again, this makes sense when you consider that behind that mouth are two huge rodent teeth.

To be continued

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