A rule small enough to hold

This demo note accompanies Interval, the sample generative study.

A field of equal marks is easy to overlook. Its regularity becomes the background. Move a handful of those marks, though, and the field begins to describe the displacement.

The first rule was small: every line has the same length, and each line begins one fixed interval below the previous one. The second rule made a fold: inside a central band, move the endpoints by a stepped amount.

One change at a time

It was useful to keep the line length still while changing the displacement. Otherwise two variables could claim responsibility for the result. A smaller change gave a clearer answer.

The bright region arrived last. It marks the place where the repeated rhythm becomes difficult to follow. In an earlier specimen, the accent appeared in several places. Removing those extra accents gave the fold a center.

There is no need to pretend the rule explains everything. It explains enough to make another specimen, compare the two, and decide which question to ask next.