Percentage measurement proceeds by determining the distances on a shape by simplifying its sections into percentages.¹ I first learned of percentage measurement from my instructor, Jeremy Deck, a few months ago.
In the image above the right side of the shape has been divided into two percentages. By seeing more specifically how the two segments of the shape appear I can better judge the accuracy of that shape.
Internal measurement is focused on determining the distances within a shape by moving from point to point within a shape.
Point to point measurement can be applied to the spaces within a shape as well as the spaces within a mass of shapes. Although much point to point measurement is done just by scanning one's eyes over the subject and the drawing simultaneously, one can trace these imaginary lines in the air for additional clarity of the point to point measurement.
Contour measurement proceeds by moving from point to point along the contour of a shape to check the accuracy of the segments of a shape.
It is helpful to think of contour measurement as moving along the segments of an animal shape to see if the line segments in one's drawing correlate to the character of the animal shape that one sees. Point to point measurement is just a tool to represent the character of the shapes that one sees, and I have found it very important to only use it as a tool. It has been crucial for me to verify the findings that point to point measurement show me by checking it to the animal shape(s) that I see.
Directional measurement proceeds by counting the spaces within a shape along a straight directional path.
The example above shows the points where one's eye would stop along the directional path. Any directional path can be used to check points across a mass of shapes whether it be horizontal, vertical or diagonal.
Triangulation proceeds by selecting three points on a shape and determining the size of the triangle that the three points produce.
It is very helpful to think of the triangle produced by triangulation as a slice of pizza because one's relation to the idea of the size of a slice of pizza makes it easier to compare the size of the triangle on one's drawing to the size of the triangle that one sees on the subject.