Line Series Problem

[Nitin]

Hi,

We are using TeeChart for .NET Ver 3.5. I've come through strange problem with line series. Our application plots x,y data in point series and allows to draw straight lines calculated from these data. I use line series with two x,y values to draw straight lines. In next step, application tries to find intersection point between two lines.

In un-zoom mode everything works fine and line intersection seems ok but as you zoom in further on the intersection point, it tends to move from the original position and shows wrong intersection point.

In the attached word file, the first image shows right intersection point. In next image you can see that it has moved down in zoom mode. I am also uploading sample project.

Please let me know as soon as possible.

[Narcís]

Hi Nitin,

I'm afraid this is a rounding problem. I have added it to the defect list (TF02014802) to be investigated for future releases.

[Marc]

Hello,

We can suggest a workaround to this issue. If a smoothing function is applied to the Lines whose cross-point is to be viewed, then using the smoothed (interpolated) lines, the accuracy of points in relation to the plotting area remains true and the cross-point itself retains accuracy.

When TeeChart applies the smoothing function it divides the smoothed line into smaller segments of the source line, for a straight line that line will remain straight but the location of the nearest [sub]point to the potting area is much nearer and there is far less margin for rounding errors.

You can see that in the demo linked here: http://www.steema.com/files/public/teec ... rtZoom.zip. There is no need to show the original (source) lines and the option checkboxes in the demo allow you to show/hide those lines. We've added a cross-point pointer (circular-point) to show where the crossover should take place. We've found that the plot quality is substantially better in TeeChart 2009 and for that reason we've included the executable demo with eval 2009 TeeChart.dll in the zip so that you can see it and compare results to those obtained with version 3.5.

Regards,
Marc Meumann

[Nitin]

Hi,

Thanks for the workaround. It works fine.

Regards

Nitin