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Advice on using julian day with the image function? [message #91406]

Thu, 09 July 2015 14:08

sally.benson2
Messages: 3
Registered: July 2015

Junior Member

Hi,
I have always used direct graphics but now I am converting over to the idl function graphics. I am trying to create a time by height plot of radar reflectivity. Here is the code I am using:

refd is radar reflectivity [time,height]
julidan_day is the time array in idl's julian day
height is the height array in meters

p3=image(refd,julian_day,height,position=reform(pos[0,*]),$
/buffer,rgb_table=my_table,image_dimensions=[400,400])

The error I am getting is
% QHULL:
qhull precision error: 101 attempts to construct a convex hull
with joggled input. Increase joggle above 'QJ0.12'
or modify qh_JOGGLE... parameters in user.h

The image function is trying to put my data on a regular grid using qhull but it is failing because the julian_day numbers are too big? How can I get the image function to use julian day? I like julian day for my time axis because it is easy to format it using xtickformat and xtickunits. I also tried seconds since 1970 but I got a similar error.

p3=image(refd,seconds_1970,height,position=reform(pos[0,*]), $
/buffer,rgb_table=my_table,image_dimensions=[400,400])

% QHULL:
qhull precision error: 101 attempts to construct a convex hull
with joggled input. Increase joggle above 'QJ5.1'
or modify qh_JOGGLE... parameters in user.h

Has anyone been successful in using julian day with the idl image function? Any help is greatly appreciated.
Thanks!
Sally

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[Message index]

		Advice on using julian day with the image function? By: sally.benson2 on Thu, 09 July 2015 14:08
		Re: Advice on using julian day with the image function? By: Helder Marchetto on Fri, 10 July 2015 06:04
		Re: Advice on using julian day with the image function? By: sally.benson2 on Mon, 13 July 2015 08:47
		Re: Advice on using julian day with the image function? By: sally.benson2 on Mon, 13 July 2015 08:46

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