20010117: McIDAS FRNTDISP errors while overlaying on zoomed images

>From: address@hidden
>Organization: SMSU
>Keywords: 200012301857.eBUIvlo29945 McIDAS-X 7.70x FRNTDISP

Bill,

>Here's an interesting item, not earth-shaking, but interesting..
>when I try to overlay a FRNTDISP on a 1km GINI, I get an error:
>IMGDISP RTGINI/GE1KVIS LAT=37 93 EU=IMAGE MAG=2 
>(very nice image)
>FRNTDISP                                                                      
>FRNTDISP - Begin                                                              
>FRNTDISP: RASTER SCAN LIST OVERFLOW                                           

>From address@hidden Fri Jan 19 12:31:17 2001
>OK, I tried a bunch of things, and I can reproduce problems with any
>type of imagery if I blow it up a bunch.  Had to blow up the
>GE-VIS mag=6 to get it to bugger, but it did.  My original problem
>was GINI 1k stuff, which lends itself to high magnification.

>Not a big deal.  Just thought you might like to know.

I worked over frntdisp.pgm on Friday and found the cause of this problem
(buffer overflow while filling in plot points along a front segment).
The code was not checking to make sure that it wasn't trying to add
values to array locations that were not allocated.  The real cause
was that the increment between plot points was set to a fixed value
when it should be variable.

Anyway, I updated FRNTDISP and tested it on a couple of different systems
(AIX and Linux) while overlaying on images that were loaded with
blow-ups/blow-downs ranging from +50 to -20.  Looks like this problem
is history.

I put out the 4th addendum to 7.7 (7.704) just a few minutes ago.  Please
refer to:

http://www.unidata.ucar.edu/packages/mcidas/770/mcx/addenda.html

for information on the Unidata McIDAS-X addenda process.

Tom

>From address@hidden Mon Jan 22 07:32:48 2001
>Subject: Re:  20010117: McIDAS FRNTDISP errors while overlaying on zoomed 
>images

Thank you Tom, once again.

Bill