XY Graph shows phantom dots when zoomed

[Shan]

I'm plotting a large data set versus time in an XY graph.  When I zoom in, the plot shows the data, plotted in lines, but also shows a large number of phantom dots.  When setting the plot to "lines & markers" the phantom dots disappear.  See attached jpg.

Has anyone seen this / have a solution?

[G-Money]

It seems to me to be either a bug with graphs or a redraw issue (OS bound and not exactly LabVIEW issue). I haven't seen it myself though. Is it possible to replicate the issue with a smaller VI and an array constant for the values? If so then that would be really helpful to post so we can debug.

Here (attached) is a VI I created to try and find the bug but was unable to. This doesn't mean that this issue is only on your machine but just means that we need to dig a little deeper to figure out what causes it. I created it in LabVIEW 2012 but saved this back to 8.0 so you could take a look at it.

[altenbach]

Can copy the graph (containing data showing the problem) to a new VI,  and make the current values default (right-click...data operations...make current values default). save the VI and attach it here. 

[Shan]

Attached is a small vi with the data in the xy graph that shows the problem.  You should be able to zoom in and see the effect.  Toggle the switch to see the problem disappear and then re-appear.  This is how I'm changing between plot types in my program.

BUT . . .

In my vi, if I make the Plot Legend visible, then change the ploty type >Common Plots>lines & markers, then switch back, the dots then are gone.  So it seems to behave differently depending on whether the plot type is changed programatically or via the Plot Legend.  Though I'm not sure why the dots show up in the first place . . .

Let me know if you can reproduce with this vi.

[Darin.K]

I do not see the problem.

[billko]

Are the phantom dots selectable?  Might help distinguish if they are "real" false data or if they are video artifacts...

[Shan]

No, these dots are not selectable.  When I enable a cursor, it tracks with the data I'm plotting only.  As far as I can tell, it's just a video artifact - maybe a bug, maybe related to my video / driver / etc.

Tim

[billko]

I was thinking it was video artifacting when I saw your first post, but I never take anything for granted.  I think it might be a combination of video driver and LabVIEW, because my display sometimes leaves a line or two of artifacting when I delete a structure, for instance.  If I scroll the BD to hide that place, it looks fine when I scroll it back...

[Shan]

The graph is a Modern graph (with borders painted white to match background). 

So here's more strange behavior.  If I REPLACE one of my existing graphs with a Classic Modern or Silver XY Graph, the behavior stays the same - phantom dots on zoom.

However, if I create a NEW XY Graph, the dots never appear.  See attached.

I'm not sure what's happening here.  If I copy a problematic graph into a new vi, the phantom dots stick with the copied graph.

This is a somewhat old vi originally started around 2005 or 06.  It's been updated thru the years with LV upgrades, currently on LV12.0f3.

I could create all new XY graphs, but that's not insignificant as I've got 12 graphs (with references) in this vi.

Suggestions?

[Darin.K]

I am not shocked to see that this is a control that has been upconverted several times.  It is a rare, but not unheard of problem.

Long-term solution is probably to replace the graphs and start from scratch.  12 is not so many in the grand scheme of things.

Things to try:

Use Paste-replace instead of replace from the Right-click menu.  This preserves fewer properties. (Drop a fresh Graph, select and copy it, select a bad graph, Ctrl-v to replace it).

If that fails, replace with some unrelated control (say a numeric) with the right-click menu.  Next replace this with a new Graph.  Also keeps fewer properties around.

Kluge is probably to use a point+line plot with the points chosen to be single pixels.