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File Formats


BYU
Reads and writes formatted byu surface files. Both read and write capability is restricted to files that contain one triangle mesh component.

Fast
Reads and writes binary and formatted unstructured triangle surface and volume grids. The Fast structured grid format is identical to the Plot3D format.

Felisa
Reads felisa surface and volume grids.

Gridgen
Reads and writes formatted and binary surface and volume files. Can also write formatted curves file if jdim and kdim are 1.

Hess
Read and write supported for hess files.

Inventor
Write capability of quads, triangles and structured surface grids are supported in inventor format as an indexed face set. Color directives can be used to set the surface patch colors. The header of the file contains items that are commented out which may alter the appearance of the data set.

LaWGS
Reads and writes formatted structured surface files written in the Langley Wireframe Graphics Specification format.

PATRAN
Reads a Patran Neutral file and converts its contents to unstructured quads. This data can be written out in any format the supports triangles or quads. The write generates a patran neutral file containing a list of nodes and triangle elements.

Plot3D
Reads and writes formatted, binary, and unformatted surface and volume files. Input files may be single block or multi block, however, output is always multi block. Iblanks are optional in reading or writing. Iblank information is not supported by any other format, therefore this option is used to strip iblanks from an existing Plot3D file or to convert a binary file with iblanks to/from formatted or unformatted.

Pro Engineer IBL
Reads and writes Pro Engineer's IBL format.

STL
Reads and writes formatted stereo lithography files. The REMOVE_COLLAPSED directive may be useful when writing this format.

Tecplot
Reads POINT and BLOCK zones and writes POINT for structured surface and volume grids, TRIANGLE and TETRAHEDRA zones for unstructured trangle surface grids and volume grids respectively, and QUADRILATERAL zones for unstructured quad surface grids.

VGrid
Reads surface and volume grids as triangles.

Wavefront
Writes a wavefront object file for structured, triangles, and quads all as an indexed face list.

WriteP
Reads a writep file as a single surface or as a list of curves.

XYZ
Writes a raw xyz file. This option just dumps the all the xyz triples to a file.


You can reference this conversion chart to determine if the conversion you need is supported.



General Rules for Conversion


Alchemize does not process directives in the order specified in the directives file. This is a shortcoming due to the way the code evolved for processing the directives and will be corrected in a future release. The list below describes the actual order directives are processed currently:
  1. Remove unwanted data specified by inclusion/exclusion directive.

  2. Strip faces (structured input only).

  3. Convert data for compatibilty with output format (structured to unstructured triangles or quads to triangles).

  4. Remove duplicate points and collapsed triangles (if requested and input is triangular surface grid).

  5. The apply, swap, and reverse commands are applied in the order specified in the directives file.




Operation

Interactive

The interactive version is invoked by typing alchemize with no command line parameters. The menu options presented in the interactive version can be selected by pressing the corresponding number or key, then pressing return or enter.

Batch

Batch mode is invoked by executing alchemize with four arguments: input options, input file, output options, and the output file. The following example converts a binary Gridgen volume file to a binary Plot3D volume file:
	alchemize -gbv classv.dba -pb classv.bin

You can obtain a list of the command line options by typing "alchemize -h" on the command line.


Directives File

Alchemize reads directives from a file specified on the command line using the -D option. Directives are classified into two groups: declarations and commands. Each declaration is specified in a block format where the directive name is the start of the block and the keyword "END" is used to terminate the block. Commands and their arguments are expressed on a single line. A line is treated as a comment if the '#' character is in column one.

Declarations

COLORS
Allow specification of colors to be used in Inventor file output. Colors are specified by a red, green, and blue component, each value in the range from 0.0 to 1.0. The colors are used sequentially, one for each object written to the Inventor file. If the number of colors is less than the number of objects, the colors are recycled.

	COLORS
	   r1 g1 b1
	   ...
	   rN gN bN
	END

GROUP
Creates a named group which consists of the specified components. This will allow a set of components to be addressed in other commands by a single name. The component can be listed individually or by specifying ranges which is the low number and high number separated by a hyphen (numl-numh).

	GROUP gname
	   num1
	   ...
	   numl-numh
	   ...
	   numN
	END

TRANSFORMATION
Transformations are declared as a named entity which consists of a series of rotate, translate, and scale operations. The transformation is applied using the APPLY command and each of the operations are performed in the order they are declared. The ROTATE operation adheres to the right hand rule and requires the rotation axis (letter X,Y or Z) and the angle in degrees. By default, the rotation is about the origin unless another point is specified. TRANSLATE requires a delta in the x, y and z directions. SCALE requires a scaling factor for the x, y, and z directions and will be performed about the origin if a point is not specified.

	TRANSFORMATION tname
	   ROTATE axis angle [x y z]
	   TRANSLATE dx dy dz
	   SCALE sx sy sz [x y z]
	   ...
	END

Commands

SWAP
Swaps the I, J, or K directions or the X, Y, or Z coordinates. Its first two arguments are from the set of letters (X,Y,Z) or (I,J,K). 'gname' can be a group name or the component number.

	SWAP dir1 dir2 gname

REVERSE
Reverses the order of the points in the I, J, or K directions. The first argument is the letter (I,J,K) and gname is either the group name or the component number.

	REVERSE dir gname

APPLY
Applies a transformation to a group or component. The first argument is the transformation name and the second is the group name or the component number.

	APPLY tname gname

INCLUDE/EXCLUDE
Selectively writes blocks/zones to the output file. This works for any file that contains more than one zone, block, or face. The numbers listed corresponds to the block/zone ordering in the file, and begins at 1.

	INCLUDE gname 
	EXCLUDE gname

SURFACE_PATHS
Specify the number of surface paths to be generated in the u and v directions for patch 33 data in a Patran Neutral file. The default is 5.

	SURFACE_PATHS num

SAME_PT_TOL_SQ
Specifies the tolerance used in comparing two points to determine if they are the same. The tolerance is specified as the distance squared between the two points.

	SAME_PT_TOL_SQ  val

TRI_AREA_FACTOR
Specifies the multiplier used in determining which triangles are to be considered collapsed. The average of the area of a triangles in the grid is computed and multiplied by TRI_AREA_FACTOR. This value is used as a lower limit for identifying collapsed triangles.

	TRI_AREA_FACTOR val

REMOVE_DUP_PTS
This command will remove all duplicate points in a triangle surface mesh. It uses the SAMEPTTOLSQ for determining candidate points for removal.

	REMOVE_DUP_PTS

REMOVE_COLLAPSED
This command will remove all triangles from a surface mesh that are considered collapsed. It uses the MINIMUMTRIAREA for determining candidate triangles to remove.

	REMOVE_COLLAPSED

QUALITY_CHECK
Tells alchemize to check unstructured surface grids for quality. It indicates the percentage of triangles that fall in a certain range of quality. The ranges are normalized from 0 to 100 where 100 is an equilateral triangle. By default the range is divided into 20 sections or bins but can be overridden.

	QUALITY_CHECK bins

Example Directives File

# Declare colors red, yellow, cyan, green, and blue
# for inventor files
COLORS
   1.0  0.0  0.0
   1.0  1.0  0.0
   0.0  1.0  1.0
   0.0  1.0  0.0
   0.0  0.0  1.0
END

# group components 1,2, and 4 and call it FRED
GROUP FRED
  1-2
  4
END

# group components 1 through 6 and call it BARNEY
GROUP BARNEY
  1-6
END

# declare transformation T1 with a translate
   TRANSFORMATION T1
   TRANSLATE 0.00 0.25 0.00
END

# declare transformation T2 as a X axis rotation if 30 degrees
# about the point (0.10, 0.75, 0.50)
TRANSFORMATION T2
   ROTATE X 30.0 0.10 0.75 0.5
END

# only write out the group BARNEY
INCLUDE BARNEY

# apply transformation T1 to group FRED
APPLY T1 FRED

# apply transformation T2 to component 3
APPLY T2 3

# reverse the J direction of component 5
REVERSE J 5

# swap I and J of group FRED
SWAP I J FRED

# change surface paths for Patran Patch33 data
SURFACE_PATHS 15


Platforms


Executable binaries are available for the following platforms:

SGI
Compiled using gcc v2.6.3 under IRIX 4.0.5

Risc 6000
Compiled using gcc v2.6.3 under AIX 3.2

Sun
Compiled using gcc v2.6.3 under SunOS.1.4


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Comments and Questions
Last Updated:Nov 17, 2011