Day 3 of Week 5 of The Art & Science of Drawing was about sighting (measuring) angles.
If I have understood it correctly, the sighting process works something like this:
- first align the sighting instrument (pencil, for example) so that it is parallel with the drawing plane,
- move to the subject, keeping your elbow locked
- rotate the sighting instrument to align it with the line you want to measure (the line can be explicit or just some imaginary line connecting two landmarks of your choice)
- back to the drawing paper, again keeping your elbow locked
- draw lightly the first approximation of your line on paper (if you've kept the elbow locked all the time, the sighting instrument should be still parallel with the drawing plane at this point)
- compare your drawn line with that on the subject and, if necessary, adjust it
- darken the line when you get confident you've got the correct angle
I think the trick and important part is to have the sighting instrument parallel with the drawing plane when you take the measurements from your drawing.
The homework was relatively simple, but took a lot of blood, sweat and tears:
- use some boxes as references
- sight 50 lines on your drawing paper
- the lines could start anywhere on the paper