[Paraview] how not to scale the thickness of the Arrow Glyph?

[Kazuyoshi Furutaka]

Dear ParaView experts,

I'm visualizing paths of neutrons in some media.
Now I prepared the data as point data with displacement
vector to the next point attached to each point, and
visualize them using the Glyph filter with the following
setting:
  Glyph Type: Arrow
  Orientation: Orient
  Scale Mode "vector"
  Scale Factor = 1.0
  Glyph Mode: All Points

The problem is that some arrows are too thick...

So here are my questions.

(1)How can I make the thickness of the arrows not
   to scale (only the lengths do)?

(2)It may be better to use "2D Glyph" instead of
   "Arrow", but the 2D Glyph is centered at a
   data point, instead of starting from the point...
   How can I make the 2D Glyphs start from the data
   points?

(3)Do you have any recommendation on how to visualize
   such a particle paths?

Thanks in advance,

Kazuyoshi
--
Kazuyoshi Furutaka
furutaka _dot_ kazuyoshi _at_ jaea _dot_ go _dot_ jp
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