Is it possible to tell RVIZ which markers (perhaps via namespaces) should appear on top?

I am displaying a map in the form of a graph, where the nodes are markers of the type POINTS and the edges are markers of the type LINELIST. I am also loading an image to RVIZ, and I would like to show the POINTS and LINELISTs on top of the image, however I haven’t found a way of doing this.

After some testing, it appears to me that using the 'points' member of visualizationmsgs/Marker, which is used by markers of the types LINESTRIP, LINELIST and POINTS, somehow prevents the markers from showing in front of the rest. If for example, I use CYLINDERs instead of POINTS, then they appear in front of the image. How could LINELISTs or Points be sent to the front? Or in general, how could one choose the order in which namespaces are displayed?

Thanks in Advance!