Sunburned Surveyor a écrit :
> [2] Why wrap simple geometries in an ISO or OGC specification? Is
> there a FOSS Java library for representing simple geometries that
> offers serious competition for JTS? Are there any plans for such a
> library in the future? I wonder if it is worth the additional
> complexity of such wrapper interfaces if there currently isn't, and
> won't be such an alternative in the foreseeable future.
JTS is very good as a starting point, but it is designed for a two-dimensional
cartesian space only, with points joined by straight lines only. JTS
coordinates
can have a "z" value, but it is not used for computation; so JTS can be said to
be 2.5D.
Cartesian coordinate system are suffisient when working in a local area using
some ProjectedCRS. Things become more complicated if we try to work in
GeographicCRS or if we try to represent a large area like a continent.
Creating a 3D library is not just a matter of extending JTS API. A 3D library
needs a really different API. Even if we want to stay in 2D, some way want
curves in addition of straight lines.
ISO Geometry API allows all that: 2D, 3D, straight lines, curves, ProjectedCRS,
GeographicCRS. JTS API do not allows that and will not in my understanding of
Martin Davis's future plans.
If we get the GeoTools library to work with ISO interfaces rather than JTS
object directly, we get both:
* The capability to use different libraries than JTS (Jody enumerated many).
* A more powerfull (at the price of more complexity) API capable of doing
things that JTS can not (3D, etc.).
However as you point out, the fact is that JTS is the most widely used geometry
API in Java at this time. So in the same way that we have Envelope
implementations backed by JTS Envelope or Java2D Rectangle2D (at user choice),
there is an interest to have ISO Geometry backed by JTS objects or by some
other
library. User would see ISO interfaces only, but JTS objects would be used
under
the hood. Later as time allow, some non-JTS objects could be put in the mix for
3D, curves, geometry on a GeographicCRS, etc.
Martin
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