Maciej Sieczka wrote:
Markus Metz pisze:
I thought this is true for GRASS. Generally, if you zoom/pan beyond
the extend of the feature (raster or vector), nothing is displayed.
This should not happen in latlon,
Why not?
Because it does not happen in GRASS:-) and because latlon is not a true
projection and because IMHO this is a nice feature and because other
GRASS developers have thought long about how to handle latlon in lib/gis
and I see no reason to question the current solution.
What about other world-wide CRSs, like those based on sinusoidal,
Goodge, Mercator projections - does GRASS wraps world edges for them as
well?
No idea, you can check.
Is there anything that could be done for v.in.gshs in GRASS 6.5 so that
it's output (when the input is a full GSHHS extent) would be free of the
horizontal longitudal extent-wide artifacts in case of:
1. editing in v.digit
2. exporting with v.out.ogr (that's another issue I haven't mentioned
yet)
3. displaying and editing in QGIS
Yes for 1, can't say for 2, No for 3. AFAICT, v.out.ogr itself does not
produce these horizontal lines, they are produced by the application
rendering the vector. Different applications have different, often
incompatible policies, therefore it is not possible to accommodate every
application. Either the GRASS display is 100% ok or digitizing is 100%
ok, both is not possible with the full dataset. Actually, the mere
display is always ok, but zooming to the selected map may or may not
work. It does not work when the longitude map extends are > 360, but
then the digitizer works... QGIS insists on straight lines also without
wrap around in v.in.gshhs. It seems that QGIS wraps coordinates beyond
-180 and 180 around into the -180, 180 range, then may draw these
horizontal lines, and restricts the display area to -180, 180.
I want v.in.gshhs to produce output that is compatible with GRASS, and
there I stop because it is not possible to accommodate every application
(see also r.out.gdal discussion).
FWIW, I have submitted changes to make the digitizer work, no more
horizontal lines there, tested with grass-6.5.
Markus
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