sisgen

NAME

SYNTAX

sisgen [options] <input xss or p?m file> [output p?m file]  

DESCRIPTION

It takes an .xss file or a .polyh file as the 3D input data or alternatively a .p?m file as the depth map and optional switches as its command line arguments.  

Options

All these options can be abbreviated to the least letters needed to make the chosen option distinct. The default values are given in parentheses.

-geometry <wxh>

sets the picture geometry, this defaults to the values given if the input is 3D data otherwise it defaults to the depth map size. (770x476 or 720x445)

-background <b>

sets the background plane z=b*OY. (-1.0)

-reverse

sets sisgen to cater for crosseyed viewing, by default it caters for wide-eyed viewing.

-enlarge <ef>

specifies the enlargement of depth effect in the final image. (1.0)

-mag <mf>

sets the magnification of the scene, only applies to 3D data. (1.0)

-pmm <res>

sets the dots' resolution in units of pixels per millimetre. (4.0)

-fine <0-8> <tol>

sets the smoothing factors which sisgen uses for colour interpolation. (0 1)

Sisgen uses buffers which are integer based. So for smoother stereograms, the numbers are scaled up by powers of two. In finding hidden surfaces in the stereogram, the integers in the buffers are compared and, if found with a certain range of each other, a point is considered visible.

The first parameter is the multiplying factor in powers of two, whilst the second gives the maximum absolute difference of values found in the hidden surface check.

For example, "-fine 2 7" means the numbers are first multiplied by 4 (2^2) and if found to have an absolute difference less than or equal to 7 then the corresponding point is visible.

-tile <0-8>

sets the tiling method to use. (0)

In all, sisgen allows nine different methods of using a tile to make a SIS.

Leave tile as it is and

0

start from left

1

start from centre

2

start from right

Scale the tile to fit on the background plane and

3

start from left

4

start from centre

5

start from right

Scale each line from the tile to fit the deepest plane that contains a point on that line and

6

start from left

7

start from the point in question

8

start from right

-image <pxm file>

gives the name of the tile to be used in making the autostereogram.

-xss

signifies that the input file contains 3D data and is either an .xss or a .polyh file. This is the default.

-dmap

signifies that the input file contains a depth map and is a grey-scale or colour portable pixmap, .pgm or .ppm.

-step <XxY>

gives the steps sisgen uses to traverse the depth map. (1x1)

The technique for making a stereogram from a depth map involves interpreting the map as a very fine rectangular net then projecting this to two buffers.

This method is quite slow for large depth maps, so to speed up the process the net is made coarser by skipping intervening points in both the x and y directions.

For example, "-step 2x3" means sisgen uses only alternate values in the x direction and every third value in the y direction.

-RANDOM <0-2>

specifies which type of random tile to generate. (0)

There are three kinds of random tiles: 0) black & white; 1) grey-scale; and 2) colour using a rainbow palette of 24 colours.

-zblines <zb>

sets the number of lines that each z-buffer will use, see xpgs(6). (256)

-input

turns on pipe mode to read a p?m file from stdin.

-output

turns on pipe mode to write the resultant p?m file to stdout.

-DENSITY <0-255>

sets the density of black dots in the SIRDS. (127)

-help

prints a summary of command line options and returns to shell.

Once running, it will load the input file, display a few parameters, request a filename (if one was not specified) and save the SIS. If sisgen is in the pipe mode then it just loads in the file(s) and sends the result down stdout. An example of using the pipe mode is "sisgen -o foo.xss | xv -".  

FILES

BUGS

If you find any bugs, please report them to the author listed below.  

SEE ALSO

cvtopolyh(6), cvtoppm(6), mkpolyh(6), sisgen(6), vpgs(6), xpgs(6) and xss(6).  

AUTHOR, COPYRIGHTS, AND WARNINGS

Copyright 1994, 16th November.

By Peter Chang. All rights reserved.

peterc@v2.ph.man.ac.uk

Version 1.0

See notice in the xpgs man page.

Index

NAME

SYNTAX

DESCRIPTION

Options

FILES

BUGS

SEE ALSO

AUTHOR, COPYRIGHTS, AND WARNINGS