Re: CellFill and Irregular grids

Hi Carl,
There is a way to get "CellFill" (or non-smoothed "RasterFill") mode
plots to
show the full cells at the boundaries of the plots. You can provide
coordinates as
cell edges rather than as cell centers by specifying coordinate
arrays that have one
more value than the number of data points along each axis. However,
it is slightly more
complicated because NCL variables cannot have such arrays as part of
their
metadata. So what you need to do is eliminate the coordinate arrays
attached to
the variables and instead set the resources sfXArray and sfYArray
directly.

I am attaching a modified version of your script that achieves this
in the first
frame.

Regarding the use of irregular axes, an irregular coordinate axis
will never work if 2
elements have the same value. This violates the essential condition
that the
values be monotonically increasing or decreasing.
  -dave

On Jun 4, 2009, at 9:26 AM, Carl J. Schreck, III wrote:

> I'm trying to plot a very sparse dataset with cnFillMode = "CellFill",
> but I notice that it makes the cells on the edges and corners smaller
> than the others. It looks like it cuts them off in the middle. I
> realize it has to do that for contouring, but I was hoping CellFill
> could get around it. Is there a workaround?
>
> One idea I had was to pad the data with identical points on the edges
> that are only half a gridbox away. However, it appears that NCL has
> issues contouring irregularly spaced grids, and gives me errors like
> these:
>
> warning:_NhlCreateSplineCoordApprox: Attempt to create spline
> approximation for X axis failed: consider adjusting trXTensionF value
> warning:_NhlCreateSplineCoordApprox: Attempt to create spline
> approximation for Y axis failed: consider adjusting trYTensionF value
> warning:IrTransInitialize: error creating spline approximation for
> trXCoordPoints; defaulting to linear
> warning:IrTransInitialize: error creating spline approximation for
> trYCoordPoints; defaulting to linear
>
> Attached is a sample script that might demonstrate the issues I'm
> talking about. Thank you for your help!!
>
> Cheers,
>
> Carl<grid_irreg.ncl>_______________________________________________
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