Andrea,
Both your descriptions are logically correct, but insanely
inefficient approaches.
Another way of saying "vector to raster" is "rendering". The
existing rendering code in geotools should provide some fine examples
of turning vectors into rasters.
For raster to vector, your earlier post where you looked at GRASS was
a good starting point. Stealing the approach from GRASS and re-
coding in Java will probably take you no longer than implementing
your logic below, and will be much faster, guaranteed.
Paul
On 6-Jan-06, at 2:10 PM, andrea antonello wrote:
Some time ago I posted a question about how to convert features to
rasters and back.
I thought an simple way would be the following, assuming that my
raster is represented by a matrix grid.
v.to.rast:
looping through the rows and columns of the matrix, query if the point
given by the coordinates (found through row and col) is inside the
geometry of the feature to rasterize.
r.to.vect:
looping through the matrix, for every cell that has a value to be
vectorized, create a polygon geometry of xresolution by yresolution.
In the end join all the polygons to a single polygon.
This can be awfully memory intensive, but it's a fast way to code and
should work.
Instead, I'm having problems with this. The the resulting geometry
doesn't exactly trace the raster. It is more or less the same as the
raster, but as I said, just more or less, which is not very scientific
:)
I'm not very expert in features yet. Does anyone see what I couldn't
see, notice some trouble?
Thanks,
Regards,
Andrea
--
______________________________________________________________________
______
HydroloGIS - Environmental Open Source Solutions
www.hydrologis.com
Andrea Antonello
Environmental Engineer
mobile: +393288497722
"Let it be as much a great honour to take as to give learning,
if you want to be called wise."
Skuggsja' - The King's mirror - 1240 Reykjavik
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