Re: Java3D 1.3 Objects vanished AND resampling Irregular2DSet

Hi Desiree,

If you have horizontal layers and look at them from the side,
it will be hard to see actual information even if you make
the layers thick - you will just see a sort of horzontal bar,
sort of like looking at a table edge.

There are a bunch of tricks you can play with VisAD to get
different views of data. Given a terrain surface ((x, y) -> z)
you can map z to both ZAxis and IsoContour and ask for a
contour line at a single z level, with a ConstantMap to
LineWidth for thick lines. If you have a terrain layer plus
multiple hydrogeological layers, you might use ConstantMaps
to ZAxis to stack them up vertically, and then look at them
from an oblique angle.

Or you might have a number of FlatFields with MathTypes:

  ((x, y) -> (zN, layerN))

where each layer is on a terrain surface offset in the z
direction by a constant amount from the original terrain.
You could have ScalarMaps of each zN to ZAxis, all with
indentical calls to setRange(), and ScalarMaps of each zN
to SelectRange, where the ranges for each zN are offset
by the amount of its offset from the original terrain. This
would produce a stack of terrain slices, one for each hydro
layer.

Good luck,
Bill

Desiree Hilbring wrote:
> 
> Hi Bill,
> 
> okay maybe I should tell your first my original intention.
> I have 1 terrain layer and several hydrogeological layer in my 3D-view.
> They are all created with VisAD, grabbed and included in my own Java3D
> scenegraph. That is working fine. What I want know, is to define
> horizontal slices through that scene, so that I get a kind of 2D-View,
> where I can see the profile of the hydrological layers.
> It is easy in Java3D to clip the 3D scene with the ModelClip function. But
> unforetunately looking at the shapes directly from the side, makes them
> almost invisible. So I thought using Volume rendering I would get a real
> profile of the slice.
> 
> >
> > You can construct an Irregular3DSet from your Irregular2DSet using
> > the appropriate Irregular3DSet constructor signature, but it would
> > have manifold dimension = 2 (because it is just a 2-D surface
> > embedded in 3-D). You cannot resample from a 3-D Set with manifold
> > dimension = 2.
> 
> That is, why I am wondering how or if it is possible to add the thickness
> values to my Irregular2DSet.
> My original data gives me the information of discrete points in 3D.
> For example
> 
> Point 1 has x,y,z coordinates and the first depth layer ends at -1m,
> the second depth layer ends at -2m ...
> Point 2 has other x,y,z coordinates and the first layer end at -1.5m, the
> second depth layer at -2.1m ...
> ...
> 
> But volume rendering is probably not really what you
> > want here, to get a good visual appearence. Volume rendering creates
> > a sort of transparent fog, used when the user wants to get an overall
> > view of volume-filling data.
> 
> Would that work for the slices?
> 
> But terrain data lies on a surface
> > rather than filling a volume, so a crisp terrain surface is better.
> >
> > To give your terrain "a bit of thickness", perhaps create a second
> > FlatField with the same domain Set as the first (your Irregular2DSet),
> > but with z values less than the z values of the first FlatField by
> > some constant. If you render both FlatFields, it will give two
> > terrains with the same shape, a small distance apart.
> 
> But from the side, I would just see two times almost nothing than ont
> times almost nothing. (My water layers are lying that way.)
> 
> >
> > If you are really ambitous you can fill in the gap between the
> > surfaces by a thin strip around the perimeter, as a Gridded3DSet
> > with manifold dimension = 2. Its grid dimensions would be:
> >
> >   2 x number_of_perimeter_points
> >
> > The tricky part would be finding the perimeter points, in order, of
> > your original Irregular2DSet.
> 
> I guess, that does not help me for the slices. I would get a kind of
> unfilled polygon, right?
> 
> >   FlatField terrain_new = (FlatField) terrain.resample(...);
> 
> okay sorry, sometimes, I am just blind.
> 
> Thanks Desiree
> >
> > Cheers,
> > Bill
> > ----------------------------------------------------------
> > Bill Hibbard, SSEC, 1225 W. Dayton St., Madison, WI  53706
> > hibbard@xxxxxxxxxxxxxxxxx  608-263-4427  fax: 608-263-6738
> > http://www.ssec.wisc.edu/~billh/vis.html
> >

-- 
----------------------------------------------------------
Bill Hibbard, SSEC, 1225 W. Dayton St., Madison, WI  53706
hibbard@xxxxxxxxxxxxxxxxx  608-263-4427  fax: 608-263-6738
http://www.ssec.wisc.edu/~billh/vis.html