| An IDL cron job, true color plots, Xvfb, Z-buffer, and all sorts of troubles [message #58593] |
Thu, 07 February 2008 02:06 |
kathryn.ksm
Messages: 10
Registered: April 2006
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Junior Member |
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Hi folks,
This newsgroup has been a huge help to me with these sorts of problems
in the past, and I am hoping once again to draw on your expertise.
My problem is a little complicated. I have a particular plotting
routine that uses a color scale to represent signal response over a
grid of detectors. I use this a lot and it's really handy. It also
took me a really long time to get it to work and to be able to
write_png files from it without getting goofy colors. What I would
like to do is automate this routine and run it with a cron job,
outputting png files to include in a daily web page.
I have noticed that quite a few people have tried to do similar things
and run into problems. I have problems with all of the suggested
solutions. Any one of them would be fine but I can't get them to
work. So here goes:
option 1) use the Z buffer: Here I think I am running into problems
with my understanding of true-color display issues in IDL. My plot
routine includes a line 'Device, decomposed = 0' and the Z-buffer
doesn't work the same way as the X buffer. That's problem number
one. Problem number two is that I can't figure out how to take the Z-
buffer plot and make a png file out of it with correct colors.
option 2) write to a ps file and convert it to png after the fact. I
have similar problems here with my Device, decomposed = 0, and I don't
understand how to translate my plotting routine so that it will do the
same thing with the ps device that it does with standard X output.
option 3) use the /pixmap option with an X window, and then use Xvfb
to run a virtual X session so that I can run this from cron. I have
Xvfb installed and with some fiddling, I can get the authentication to
work out so that I don't get an immediate Xlib: connection to ":1.0"
refused by server, but even then I still get WINDOW: Unable to connect
to X Windows display: :1.0 errors, even though the DISPLAY variable
looks to be set correctly to me. I really hoped I could get this to
work, because doing window, 1, /pixmap, running the plotter, and then
calling write_png, 'file.png', tvrd(/true) works wonderfully and gives
exactly what I want... just not through cron.
I think the main reason I'm having so much trouble here is I'm trying
to get something to work with color tables and true-color display
without really understanding them. A stripped-down version of the
plotting routine is below. I would invoke it with something like
> plot_test, [0,2,3],[0.2,0.7,1.0]. Before I run this, I have quite a
few graphics setup calls in my idl_startup file. Between running it,
I typically do
loadct, 0
!p.color = !black
!p.background = !white
to make the display look right each time.
Sorry for the long-winded question. Sample plotting routine follows:
pro plot_test, indices, color_scale,$
title=title
if n_elements(title) eq 0 then title=''
; example simple grid of 4 points:
x_pos=[1., 2., 1., 2.]
y_pos=[1.,1.,2.,2]
;plot, the center points for each detector:
plot, x_pos, y_pos, xrange=[0,3],yrange=[0,3],/xstyle,/ystyle,/iso,$
psym = 3, title = title
Device, decomposed = 0
LoadCT, 33
; determine the color scale to use
color_scale=float(color_scale)
color_values = ((color_scale - min(color_scale))/(max(color_scale)-
min(color_scale)))* 255
;plot circles filled with the colors in the scale
for i=0,n_elements(indices)-1 do begin
polyfill, circle(x_pos[indices[i]],y_pos[indices[i]],0.25),
color=color_values[i]
endfor
colorbar, /vertical, format='(F6.2)',$
range=[min(color_scale),max(color_scale)]
end
- Kathryn
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