What interpolations does GHS perform during model building?


Question:

Please verify or correct the following points:

1) When creating a model, GHS only uses the input data. No interpolation of
offsets or stations is used in the resulting model.

2) A new model can be created, using Model Converter, based on the original
data.  This process will use 1st, 2nd, or 3rd order interpolation, depending
on the station spacing, to create or delete stations.  However, this new model
is entirely separate from the old model.


3) GHS does not use interpolated offsets or stations while performing
stability calculations ( except at the waterplane endings).


Answer: 


In answer to your questions about GHS modeling:
    
1) GHS uses interpolation in several places when creating models.  The Section
Editor has the ability to enrich shapes which it creates or edits by adding
stations using linear interpolation.   Model Converter has the ability to
enrich shapes by adding stations using higher-order (2nd or 3rd)
interpolation.  Part Maker creates stations by linear interpolation in the
process of fitting tanks and appendages as well as interpolating on stations
for intersections between two shapes.
    
2) Model Converter reads an input file and writes an output file.  The output
file contains data from the input file, usually after some kind of
modification or format conversion.  The output file may also retain its
previous contents in addition to the data from the input file.  The output
file may be the same file as the input file (this is always the case in FIXUP
mode).  Therefore, Model Converter can modify an existing Geometry file or
create a new one.
    
3) GHS versions 6.50 and earlier do not interpolate additional stations during
stability calculations, except for waterplane endings.  Waterplane crossings
on stations are interpolated.