AVS Modules					       	   new arbitrary slicer
Lawrence Berkeley Laboratory				            8 July 1991

NAME
     new arbitrary slicer - slice through a three dimensional field, with
	the slice plane at an arbitrary orientation.

SUMMARY
     Name	   new arbitrary slicer

     Type	   mapper

     Inputs	   field 3D scalar float

     Outputs	   field 2D scalar float

     Parameters	   
	Name		 	Type	     Default   Min  Max	      Choices
	X,Y,Z Rotate     	float       	0      -360. 360
	X,Y,Z Translate  	float     	0      UNBOUNDED
	X,Y Scale		float		1.0    UNBOUNDED
        U,V Mesh Resolution 	integer   	20     10,500
	Undefined Value		float		-1.0   UNBOUNDED

DESCRIPTION
     The new arbitrary slicer module extracts a 2d slice from a 3d
     field.  Output consists of a 2d field (as opposed to geometry,
     as in the "normal" arbitrary slice module) which may be piped
     to other modules which process 2d fields.

     The position, size and resolution of the slice plane are under
     user control via the parameters.

     For all input fields, the module will determine "sane" parameter
     settings for extracting an initial slice.  

MODULE UPDATE NOTE FROM AUTHOR 2/94

i have ftp'ed over an updated "new arbitrary slicer" that provides
PRELIMINARY support for irregular fields.  i am very reluctant
to release this code because it uses a brute-force algorithm
which is very slow, and produces point-sampled output.  i get email
from time to time asking about this and i always tell them the
problem, that space subdivision on warped grids is a research
topic, and until somebody publishes something worthwhile on
the subject, i'm going to ignore this deficiency in this module.
so there.

anyway, when you post the notice to the net, would you please
be sure to indicate that this is preliminary support only, that
there are limitations, etc. in BIG BOLD LETTERS so people don't
whine (ignorantly, at least) about why the module is so slow,
and why it produces point sampled output, etc.


INPUTS

     Data Field, 3D, any mapping, scalar, float.

PARAMETERS

     slice plane

	  Determines the value of the array index to be	held constant.

     axis
	  Selects the dimension	(X, Y, or Z) in	which the array	index is to
	  be held constant.

OUTPUTS

     Data Field, 2D, irregular, 3-coordinate scalar float.

	  The output field is 2D instead of 3D,	and has	the same type of
	  data as the input field.  The output field, however, is
	  by definition an irregular field.

EXAMPLE
     The following network takes a slice from a	scalar volume and displays
     it:

	        READ VOLUME
		     |
	     NEW ARBITRARY SLICER
		     |	     (optionally: GENERATE COLORMAP)
		     |	 ________________|
		     |	 |
		FIELD TO MESH
		       |
                RENDER GEOMETRY
                       |
                 DISPLAY PIXMAP

LIMITATIONS
	At present (8 July 1991), this module will process UNIFORM fields
	ONLY.  It is my intent to extend this module to handle irregular
	and rectilinear fields in the near future.

AUTHOR
	Wes Bethel, Lawrence Berkeley Laboratory

AVS Modules						new arbitrary slicer
Lawrence Berkeley Laboratory				         8 July 1991