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[IDV #MLU-866031]: IDV issues with displaying "height" gridded data

Hi Tom-

Only  4 months late on answering this one. ;-)

> A few issues came up regarding a user who wanted to display heights
> (and thickness) fields, that I thought I'd pass along.
> 
> 1. in the Field Selector, when picking "3D grid -> Geopotential", the
> Display choice of "3D -> topography" is not offered.  He can do the
> display
> using "Plan View -> Color shaded plan view over Topography", but
> then must pick is Geopotential field twice.

This is by design. ;-)  The topography control was developed to
display 2D topography, not 3D heights as topography.  I've changed
the controls.xml descriptor to include Z as a valid field.  This
might have repercussions in other formulas, but I'll see what happens.
This only allows one to do a color shaded topography, not color filled
contours. 

> 2. If he picks the "Any Field" formula with a "3D->Topography"
> display, and then chooses the "3D grid -> Geopotential", he gets an
> error message at the bottom of the display window:  "Single
> DisplayRealType DisplayProjectionAlt2 occrs more than once:
> ShadowType.testIndices"

This was fixed a while ago when I refactored the Topography control
to be a subclass of PlanViewControl.

> 3. If he chooses the Formual, "Simple difference a-b", with a
> "Topography" display, and then picks the 1000mb and 500mb Geopotential
> fields, he gets the dreaded:  Vvisad.SetException: visad.SetException:
> Gridded3DSet.valueToGrid: ManifoldDimension must be 3"  error message.

It would work with sub(a,b).  I've been thinking about changing the
Simple Difference formula to that, but then I'd have to change the
workshop docs.  In general, when using grids, one should use
sub, add, mul, quo instead of -, +, *, / since the former handle
differences in manifold dimensions.

> 4. So....I guess I told him the easiest way to show his thickness as a
> topography, was to use the AnyField formula and then pick the "2D grid
> -> derived" Thickness parameter.    

With the change to allow Z as a parameter for Topography, I've added
the parameter names thickness_1000_500,Anythickness as aliases.  Now
3D Surface->Topography will show up as displays for those fields.

> I could not field a short-cut for
> him to show just the 500mb heights as topography, though....since none
> of the direct ways (the parameter itself, the "slice at level", etc)
> allow for a display type of "topography".

That should work now, but only as a shaded view.

> I don't have any solutions (other than to somehow make the
> "Topography" choice appear when the parameter has "length"
> units.....but I think that might cause some grief is populating the
> "Display choice" panel, eh?

Try the solutions I've implemented.

Of course, now you'll want the display's vertical range to autoscale. ;-)

Don

Ticket Details
===================
Ticket ID: MLU-866031
Department: Support IDV
Priority: Critical
Status: Open