In Rviz, what is the relationship between 'Scale' in 'Current View', Marker.scale and Marker.points?

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I'm struggling to understand this relationship, and I can't find any documentation or similar questions online. The Marker.points data shown below imply my Marker::ARROW should be about 37 cm long. The Marker is, however, too small to see when the Scale in the Rviz/Current View is 1. I have to set it to something large like 100 in order to see it in Rviz.

header: 
  seq: 0
  stamp: 
    secs: 1581534463
    nsecs: 887582462
  frame_id: "projection"
ns: ''
id: 1
type: 0
action: 0
pose: 
  position: 
    x: 0.0
    y: 0.0
    z: 0.0
  orientation: 
    x: 0.0
    y: 0.0
    z: 0.0
    w: 0.0
scale: 
  x: 1.0
  y: 0.5
  z: 1.0
color: 
  r: 0.0
  g: 1.0
  b: 0.0
  a: 1.0
lifetime: 
  secs: 0
  nsecs:         0
frame_locked: False
points: 
  - 
    x: -0.184888888884
    y: 1.419
    z: 0.0
  - 
    x: -0.545999999995
    y: 1.41900000001
    z: 0.0
colors: []
text: ''
mesh_resource: ''

Can anyone explain this ?

Thanks in advance for your help.

Nick