| GRIDDATA ignoring MISSING keyword? [message #34522] |
Thu, 27 March 2003 12:43 |
haffner
Messages: 1
Registered: March 2003
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Junior Member |
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We just recently moved from 5.4 to 5.6, and I was getting excited
about putting TRIGRID (especially the buggy spherical gridding!) to
rest. But, I'm having some trouble with IDL 5.6 using GRIDDATA and the
MISSING keyword for data outside of the region containing irregular
data.
Imagine that your irregular data resides in a concave surface, say an
L-shaped region. Without any 'buffering', both TRIGRID and GRIDDATA
cause 'streaking' between the vertical and horizontal sections that
contain the irregular data as the routines try to interpolate between
the sections. To get rid of the streaking, I use a buffering routine
to create a boundary of fake data points outside of the real data
region and set these to the MISSING value. When the routines
interpolate between the segments then, they just fill the formerly
streaked areas with the value MISSING. This works fine with both
TRIGRID and GRIDDATA.
Outside of that transition region, with TRIGRID points are all set to
MISSING. With GRIDDATA, they all seems to be set to 0, no matter what
you pass in for MISSING.
Any ideas how to get around this?
mh
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