>Hi,
>
>When I use autogply, null vectors, ie, [0,0,0], are represented by a
>somewhat large round blob that's quite disconcerting.  Is there a way
>to make these null vectors not to be plotted?
>
>My being an engineer, I already ``solved'' this problem by  adding a tiny
>bit of
>``fuzz'' to each vector, ie, I made something like a = [a.x+0.0001, a.y, a.z]
>in a compute module.
>
>I'm  just curious now to know if there is a correct, canonical way of getting
>the same effect.
>
>Many thanks,
>--


First, be aware that many modules, including AutoGlyph have "hidden"
parameters. Open the configuration dialog box by double-clicking the
module, then Expand to see these. That said, I don't think that any
permutation of ratio/min/max will eliminate the display of the spheres
corresponding to a mag(vector)=0.0; they just change which vectors are
rendered as spheres.

So, unless someone else provides an easier way, I would use Include to mask
these off. Include can either cull them out or you can create invalid
positions to mask them. I'm proposing to do the latter.

If the vector data is the "data" component of field F, use
mags = Compute(F, "mag(a)!=0.0"); //(or "mag(a)==0.0 ? 0 : 1")
invs = Include(mags, min=0.5, cull=0);
// you don't want cull=1 (the default) because you need a component
// of "invalid positions" of the same count as the original vector array
// to use in the next step
maskedF = Replace(invs, F, "invalid positions", "invalid positions");

Result is that every mag(a)=0 is now masked by an "invalid position" of 01,
so it won't render (they are still in the maskedF field however in case you
want to do something else with them).

Chris Pelkie
Vice President/Scientific Visualization Producer
Conceptual Reality Presentations, Inc.
30 West Meadow Drive
Ithaca, NY 14850
[EMAIL PROTECTED]

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