Open plot markers without background

Question

I want to use differently shaped and sized open plot markers to visualize overlapping data more clearly in ListPlot.

To this end I extracted plot markers according to the method proposed in PlotMarkers - are there default common shapes available?. I rescale them appropriately using:

Offset[{a_, b_}] :> Offset[scale {a, b}]

(Probably not the smartest way but it works here.)

However, there is a clear problem when using these. Intersecting lines of different markers do not show up. The open shape seems to be filled in with a background. Although that is not exactly what is happening because if I put a background behind the plot this is shown through the open plot markers.

How do I get differently shaped re-sizable open plot markers that are see-through in their interior?

Below is an image showing the "wrong" overlapping behavior that I want to avoid. I would like the shape of one plotmarker to continue under the other.

Answer 1

You can insert FaceForm[] before Disk and Polygon primitives:

{circle, uptriangle, diamond, square, downtriangle} = 
   Charting`CommonDump`GraphicsOpenPlotMarkers[][[;;5]];

scale = 4;
markers = {uptriangle, circle, square} /. {p : _Disk | _Polygon :> {FaceForm[], p}, 
     Offset[{a_, b_}] :> Offset[scale {a, b}]};

scale = 4;
ListPlot[{{1, 3, 6}, {2, 3, 6}, {1, 5, 6}}, 
 PlotRangePadding -> Scaled[.1], PlotMarkers -> markers]

Alternatively, using PlotMarkers -> "OpenMarkers" and post-processing:

ListPlot[{{1, 3,6}, {2, 3, 6}, {1,5,6}}, PlotRangePadding->Scaled[.1],
 PlotMarkers ->{ "OpenMarkers", 25}] /.
      { p:_Disk|_Polygon:> {FaceForm[], p}, 
      AbsoluteThickness[_]:> AbsoluteThickness[2]}