We seek to connect ideas in the theory of bridge trisections with other well-studied
facets of classical knotted surface theory. First, we show how the normal
Euler number can be computed from a tri-plane diagram, and we use this to
give a trisection-theoretic proof of the Whitney–Massey theorem, which
bounds the possible values of this number in terms of the Euler characteristic.
Second, we describe in detail how to compute the fundamental group and
related invariants from a tri-plane diagram, and we use this, together with
an analysis of bridge trisections of ribbon surfaces, to produce an infinite
family of knotted spheres that admit nonisotopic bridge trisections of minimal
complexity.