Re: ogc features over orthophoto over dem

Hello Andrea,

>
>
> I prototyped around a little bit adding also shapefiles to my testcase
> and I must say: visad rocks!
>
> I have huge performance problems, which I hope to resolve somehow
> later.
>
> I put the resulting screenshot at:
> http://www.jgrass.org/cgi-bin/moin.cgi/HowItIsGoingWithVisad?action=show
> I hope someone is interested in this first draft and has some ideas on
> how to do things better. I welcome all critics (Don Murray, I wasn't
> yet able to get things work following your advices, I will come back on
> that later).

Looks great! that's Trento, isn't it? I saw it in some GRASS screenshots,
but yours is looking good.>
> I have a couple of rather different questions I would like to post, in
> the hope they are not too scattered.
>
> - in visad, is there some kind of caching system that gives the
> possibility to work with huge files that can't be kept in memory? Kind
> of tiling mechanism. LIDAR and friends are a now used reality, has
> anyone experience?
>
> - in the image I made the river with a Gridded3DSet. I'm not sure if
> that is the proper way. Should I use some VisadLineArray?
>
> - also, I had to elevate the river of some meter, since in certain
> parts it went below the elevation model (which by the way is right,
> since the river is made of coarser points as the dem and the lines in
> some parts "intersect" the dem). Has anyone a better idea to overlay
> the shapefile  over the dem?

I think I'd render the shape(file) as a texture an use this as an overlay,
as Bill said. Has the advantage of making the features (aka objects: point
lines polys) always visible, but the won't allow you any interaction with
them (big drawback...). I've used the first approach and was satisfied
with the results.
You may also use some Field functions to create/interpolate mid-points and
thus resample a line into more points. (I think field.evaluate() and/or
field.resample() are the methods needed here. Sorry, been some time away
from visAD :-(

>
> - I tried to simulate a line with borders by painting a thinner after a
> thicker one of different color. The result is weak as expected, is
> there any way to do styling of lines (apart of dashing, which I read is
> supported)?
>
> And last but not least (even if really not so important :)):
> - has anyone an idea about how to put a filled polygon over the dem? I
> tried as a joke to do it with Delauny, but it doesn't permit 3D.
> Perhaps the best would be to create an image and use it as a texture
> over the dem and photo (does this last sentence make a sense?).

Hmm, there was a metod somewhere to fill in a set. (Damn! Perhaps I should
go back to some visAD programming ;-)
Now my time to ask. What API are you using to read geo data? Is it GeoTools?

Cheers,

Ugo

>
>
> Thanks in advance for any comment.
> Andrea
>
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