Andrea Aime wrote:
Hi,
I'm looking at the grid coverage readers, and found out that
AbstractGridFormat
defines WGS84 as the default crs. This is used by the WorldImagePlugin
if not
.prj file is avaiable to define more precisely the grid coverage format.
Now, this decision seems a little problematic to me. If we load a
coverage
with wld file but no prj file, and the coverage happens to be in a
projected
system (say, UTM), there is no correspondance between the grid
coordinates
(which may be in the range of the millions of meters) and the crs (that
uses -180/-180 -90/+90).
It seems to me the most sensible choice for an unknown CRS is
DefaultEngineeringCRS.CARTESIAN_2D, which has special handling to be
a good default cartesian CRS (in particular, every transformation that
involves it is an identity).
Yet this change may break some of applications that rely on the
current default
Given the quality of the raster rendering (which you just imporved)
nobody has relied on raster support yet.
So I would not worry too much.
It is however important: many people try, it is one of our top
questions on the FAQ.
It really comes down to a numbers game, just like with fetures of an
unknown projection. Treating them as CRS.CARTESIAN_2D is correct, but
often as not people expect lat/long. We try and make the most common
thing the default. Right up there on our guidelines "Use sensible
defaults" is a uDig mantra.
The question is really what is sensible In this case? I do like the
sound of CARTESIAN_2D using the identiy transform and going quickly. I
am just not sure what the majority of these non projected files are
actually intended to be in.
A couple options:
- preference, with the default being lat/long.
- check the world file, and if it falls in the 180/-180 -90/+90 range
use WGS84, and if not use CARTESIAN_2D. I figure that would be the
preference option "Guess".
- use the projection of the last thing loaded
We should also support an opperatoin to set the projection on both
shapefiles and world+image files.
Jody
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