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QTCharts: Problem with big data set with opengl support



  • Hello,

    I try to plot an data set with 129600000 points with QLineSeries. I enabled opengl support.
    With smaller data sets every thinks works well.

    If I try to plot the data set, the application starts (gray window is painted) and an nvidia error is reported by an error dialog.
    "A TDR has been detected. The app ..... must closed. Error Code: 7 ...."
    I think it is not enough memory available on the nvidia quadro m1200 of my computer. An float64 representation needs roughly 2 GB for the data set.

    To solve the problem, I have four questions

    • It could be an timeout problem with opengl <-> nvidia driver. How can I expand any timeout?
    • For plotting I do not need an 64 bit representation. Which rep. use Qt on the grahpics card and how can I reduce that to 8/16 bit?
    • Is there a method to calculate the available memory on the graphics card, which I can use to cut down the data set?
    • Is it possible to plot the dataset in partial mode? Do x loops until all points are plotted (transfer partial set of points, plot point to image, delete and next loop)?

    Thanks for all comments.



  • @thomas-enzinger

    Hi,

    is it a static or live plot? (Do your 129M points change on runtime?)

    @thomas-enzinger said in QTCharts: Problem with big data set with opengl support:

    For plotting I do not need an 64 bit representation. Which rep. use Qt on the grahpics card and how can I reduce that to 8/16 bit?

    QLineSeries takes QPoints or qreals which are double values per default. I dont know if the plot accepts shorter data types.

    BTW, I would recommend using external libs / widgets like QCustomPlot or QWT for plotting.

    This might be helpul as well (http://voidknot.blogspot.com/2014/10/extending-qwtplotitem-class-to-plot.html)


  • Qt Champions 2019

    @thomas-enzinger There is no point in showing 126M points at the same time as no display has so many points (not even close). You should consider reducing the amount of points.


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