Dropdown entry for "Actual Size" in plot layer options

[micahnyc]

In addition to fixed and linear size we would like to be able to do actual size, i.e. to have the size of a cluster in parsec

[jfoster17]

Note that as of version v1.15.0, there is the option to display arbitrary regions on an Image Viewer and these regions could be circles of a given size. A few limitations are that you would need to handle creating these regions, the regions currently only display on an Image Viewer (not on a standalone Scatter Viewer), and because the code is for displaying arbitrary polygons it is not optimized for simple cases and is a little slow for many polygons.

But I certainly thought about the simpler option of "display this thing with a given size". There are basically two main options here:

1. Specify the radius of points/circles as a single text field (i.e. all clusters have the same size in parsecs)
2. Specify an attribute/component that gives the radius of the circle in data units (i.e. clusters have different sizes in parsecs, but the data needs to specify it for all points)

In case 1 we also need to come up with a way for the user to specify the units of the size.

Can you say a little more about your use case?