2D with COLZ in "on-line" applications

From: KOSU_FOKIN@garbo.lucas.lu.se
Date: Tue Oct 12 1999 - 13:39:16 MEST


Hello rooters,

In our project (CHICSi, TSL, Sweden) we have a barrel with more than 500 dE-E 
Si-Si-GSO telescopes. It means that DAQ monitor can be easily requested to update 
a lot of 2D dE-E histograms and display them with COLZ option. Drawing 2D 256x256
(normally people ask for such resolution) with COLZ takes time even on a powerful
comp and makes it impossible to update our live display which normally has 20-50
such histograms displayed simultaneousely. So

1. I wonder if someone has already faced such problem.
2. Usually to solve this we have "static" color scheme in our home made histogram
display. I.e. let's say 

Ev.#  Col

10    red
20    green
30    blue
40    red
50    greem
60    blue
and so on

With such a scheme our "scientists" usually don't mix up things becuse they suppose to
know how dE-E plot looks like and they keep in mind that the max number of particles 
appears to be in the "center" of a dE-E banana. 

Then we don't need to recalculate every channel's color every time we Update a hitogram.
Also in "on-line" mode we do not redraw the whole histogram table but only those channels 
which are marked as "changed" (or rather those which color should be changed!).

The same kind of "on-line update" mode is defenitely required for any DAQ application.
I wonder if ROOT can/is going to provide such features? 

Best regards,
Anton



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