[vtkusers] how to modify only portion of my imagedata

[Ted Vu]

Hi

Say I have a 2D ImageData that is 100 by 100 on the xy plane

Just to give you a better sense of what I'm tryign to do, the x-axis  
represents time (so there are 100 time samples), and I have a waveform being 
rendered along this axis

So I have an array that is input into vtkFloatArray which is then input into 
my ImageData

To show the waveform moving along time, I keep updating my array and then 
calling Modified() then Render() for each time sample..

So really its my WHOLE ImageData that is being modified/updated i.e. the 
WHOLE 100 by 100 array
THis is REALLY slowing things down (my image data is actually 300 by 300, 
and I have 3 of them overlapping!)

Is there a way to just modify my ImageData along the time axis just point by 
point.. i.e. lets say I have already rendered the waveform upto 10 time 
samples, and that now its time to render the 11th time sample - So  instead 
of updating the pipeline for the whole 100 by 100 matrix, can I just update 
it for that 11th time sample (i.e. updating only 100 by 1 portion of the 
array)  and maenwhile still keep the previous time samples rendered..?

Thanks for your help vtkusers!!!!!!!!!
Jen

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