I was a bit browsing the internet for models for (2-dimensional) hyperbolic geometry.
and realised that besides the well known
- Poincare half plane model
- Poincare disk model
- Beltrami-Klein disk model
- Hyperboliod ( Weierstrass- Minkowski- Lorentz- ) model
There are also the
- Hemisphere model (mostly used for transformations between the Poincare half plane model and the other models)
And via via I came in contact with the
- Gans Model (flattened hyperboloid model, a hyperboloid model minus the z coordinate) (see Gans, David . A New Model of the Hyperbolic Plane. American Mathematical Monthly, Vol. 73, Issue 3, March 1966. or www.d.umn.edu/cs/thesis/kedar_bhumkar_ms.pdf )
This made me wonder: are there even more models of (2-dimensional) hyperbolic geometry that I should know but haven't heard of? (do add references)
I believe Hubbard uses a 'belt model' in Teichmuller Theory: Volume I, but I don't have a copy on me at the moment.
Just for the sake of completeness --- in principle, by the Riemann mapping theorem, any simply connected domain in $\mathbb{C}$ can serve as a model of hyperbolic space.
Edit: I have recently learned of a parabolic model, defined by intersecting a vertical affine plane in $\mathbb{R}^{2+1}$ with the forward light cone and projectivizing. By the same method, any conic section should define a model of $\mathbb{H}^2$.