SIMION 8.0 Issues/Bugs/Enhancements

Issue I339 [stl,enhancement,resolved]
  Improve STL->PA CAD conversion accuracy

  Prior to SL Tools 1.2.0-TEST11, STL surfaces imported into PA files
  were often distorted by roughly +-1 grid unit (gu).  The primary
  reason for this is that SIMION PA's represent solid electrodes
  with two rows of electrode points (1 gu width), as shown in
  Figure 5.3 of the SIMION 8.0 manual.  The additional row to
  make a surface solid can move the surface from the correct
  position if the additional row is placed on the outside rather
  than inside of the electrode.  A secondary reason is that
  the triangle rasterization algorithm in 1.2.0 was less than
  ideal.  Both of these issues are addressed in SL Tools 1.2.0,
  but some care needs to be taken to ensure accuracy.
  
  In SL Tools 1.2.0-TEST11, using the STL->PA conversion function,
  selecting the option "Solid strategy" = "No extra solid points" will
  convert surfaces to a single row of electrode points and not
  add the additional row to make it a solid electrode.  This
  improves field calculation accuracy, anbd it is recommended,
  although the surface now won't necessarily splat particles.
  You could ignore that issue, touch up the surface using the
  SIMION Modify function or force an ion splat (ion_splat = 1)
  via a user program (Issue I340 when implemented could also help).
  
  SL Tools 1.2 also improves the triangle rasterization algorithm,
  so surfaces appear more regular (even under other choices of
  "Solid strategy").
  
  SIMION accuracy is highest when electrode surfaces align to
  PA grid units.  This is important to consider when converting
  the STL file.  If your STL file has electrode plates at
  x=0 and x=10.5 in STL units, and if you scale the STL file
  to 0.5 STL units/gu
  (e.g. by selecting region scale = 1 mm/STL units and
  grid cell size = 0.5 mm/gu or by selecting scale = 2 mm/STL units
  and grid cell size = 1 mm/gu), then these surfaces will be exact
  in the PA file.  You should confirm correct grid unit alignment
  by taking measurements with your mouse using the SL Tools View
  function, SIMION Modify 3D screen, or SIMION View screen.

  Reported by aiofmhope-20070103 and also
    http://www.simion.com/discuss/viewtopic?p=1236
    http://www.simion.com/discuss/viewtopic?p=744
    http://www.simion.com/discuss/viewtopic?p=2409