@michaelkirk thanks for your review! I have added proposed changes

I think you'll need to run cargo fmt, otherwise LGTM

I'll leave it open for a couple days before merging in case anyone else wants to weigh in.

@michaelkirk

I've just realised that there is already the following method: geodesic_intermediate_fill. It expresses pretty much the same logic.

Do we still need this another implementation?

Darn it. I'm sorry for not realizing this earlier. This seems related to #1181

Assuming #1216 gets merged, I've got a different approach that should supersede this, generically implementing Densify for all line measures (Haversine, Geodesic, Euclidean, etc.)

You can see a WIP here: https://github.com/georust/geo/compare/mkirk/unify-densify?expand=1

My alternative to this was merged in #1231.

With that you can call:

use geo::{Geodesic, Densify, Euclidean};
line_string.densify::<Geodesic>();
line_string.densify::<Euclidean>();

Let me know if that works for your purposes @grevgeny.