Plotting

[svn]

I have a channel with 75,000 points in it that i need to plot in VB. I am using MSChart to plot this graph. I can plot the graph just fine but it is awfully slow. Does anyone know how i can make it any faster?

Any input will be appreciated.

[svn]

Alternately, does anyone know how to plot ~75000 points faster in VB? I have only tried MSChart function and that is quite slow.

[mstraf]

how do you pass the point to the chart control?
Marco

[teja8100]

Hi svn,

Even I have about 80000 points to plot. But when I use Mschart "VtChChartType2dXY", the entire plot is displayed as a thin strip. Could you please tell me how you are plotting ur 75000 point plot using Mschart. What chart type are you using?

Thanks

[svn]

1. I am reading in a binary file with points into an array and passing that array as the data that goes to the chart. Something like:

For i = 1 To Val(NumPts)
PltVals(i, 1) = ChnVals(i, t2)
Next

Plot.Chart.ChartData = PltVals

2. I am using VtChChartType2dLine.

[mstraf]

did you do some benchmark to see which part is the slowest: reading, preparing the data, or displaying it. 75000 points is a heck lot of data, that cannot be displayed all together in a normal monitor (you can get as much as 1600 pixels of horizontal resolution).
One possibility is to break the data in chunks of let's say 1000 points, adding a scrollbar or something to select the active range. If you need a zoom out view, I suggest to compress the data (1000 points or so) before sending it to the chart. When compressing, let's say 100 points into one, you can select the average, minimum or maximum of those 100 points. You have a lot of flexibility in this way.
Marco