5.8 Image Calculation Parameters
MAXITER=nnn
Reset the iteration maximum (the number of iterations at which the
program gives up and says 'OK, this point seems to be part of the set in
question and should be colored [insidecolor]') from the default 150.
Values range from 2 to 2,147,483,647 (super-high iteration limits like
200000000 are useful when using logarithmic palettes). See The
Mandelbrot Set (p. 43) for a description of the iteration method of
calculating fractals.
"maxiter=" can also be used to adjust the number of orbits plotted for
3D "attractor" fractal types such as lorenz3d and kamtorus.
CORNERS=[xmin/xmax/ymin/ymax[/x3rd/y3rd]]
Example: corners=-0.739/-0.736/0.288/0.291
Begin with these coordinates as the range of x and y coordinates, rather
than the default values of (for type=mandel) -2.0/2.0/-1.5/1.5. When you
specify four values (the usual case), this defines a rectangle: x-
coordinates are mapped to the screen, left to right, from xmin to xmax,
y-coordinates are mapped to the screen, bottom to top, from ymin to
ymax. Six parameters can be used to describe any rotated or stretched
parallelogram: (xmin,ymax) are the coordinates used for the top-left
corner of the screen, (xmax,ymin) for the bottom-right corner, and
(x3rd,y3rd) for the bottom-left. Entering just "CORNERS=" tells
Fractint to use this form rather than CENTER-MAG (see below) when saving
parameters with the <B> command.
CENTER-MAG=[Xctr/Yctr/Mag[/Xmagfactor/Rotation/Skew]]
This is an alternative way to enter corners as a center point and a
magnification that is popular with some fractal programs and
publications. Entering just "CENTER-MAG=" tells Fractint to use this
form (the default mode) rather than CORNERS (see above) when saving
parameters with the <B> command. The <TAB> status display shows the
"corners" in both forms. When you specify three values (the usual
case), this defines a rectangle: (Xctr, Yctr) specifies the coordinates
of the center of the image while Mag indicates the amount of
magnification to use. Six parameters can be used to describe any
rotated or stretched parallelogram: Xmagfactor tells how many times
bigger the x-magnification is than the y-magnification, Rotation
indicates how many degrees the image has been turned, and Skew tells how
many degrees the image is leaning over. Positive angles will rotate and
skew the image counter-clockwise.
BAILOUT=nnn
Over-rides the default bailout criterion for escape-time fractals. Can
also be set from the parameters screen after selecting a fractal type.
See description of bailout in The Mandelbrot Set (p. 43).
BAILOUTEST=mod|real|imag|or|and|manh|manr
Specifies the Bailout Test (p. 98) used to determine when the fractal
calculation has exceeded the bailout value. The default is mod and not
all fractal types can utilize the additional tests.
RESET
Causes Fractint to reset all calculation related parameters to their
default values. Non-calculation parameters such as "printer=", "sound=",
and "savename=" are not affected. RESET should be specified at the start
of each parameter file entry (used with the <@> command) which defines
an image, so that the entry need not describe every possible parameter -
when invoked, all parameters not specifically set by the entry will have
predictable values (the defaults).
INITORBIT=pixel
INITORBIT=nnn/nnn
Allows control over the value used to begin each Mandelbrot-type orbit.
"initorbit=pixel" is the default for most types; this command
initializes the orbit to the complex number corresponding to the screen
pixel. The command "initorbit=nnn/nnn" uses the entered value as the
initializer. See the discussion of the Mandellambda Sets (p. 49) for
more on this topic.
RSEED=nnnn
The initial random-number "seed" for plasma clouds is taken from your
PC's internal clock-timer. This argument forces a value (which you can
see in the <Tab> display), and allows you to reproduce plasma clouds. A
detailed discussion of why a TRULY random number may be impossible to
define, let alone generate, will have to wait for "FRACTINT: The 3-MB
Doc File."
SHOWDOT=[auto|bright|medium|dark|<nnn>[/<size>]]
Colors the current dot being calculated color <nnn> or an automatically
calculated color taken from the current palette. The second parameter is
the size of the traveling pointer in units of pixels of 1/1024th of a
screen.
The travelling pointer strobes with fast fractals because of interaction
with the monitor's vertical refresh. The orbitdelay parameter can be
used to introduce a per-pixel delay when showdot is turned on. Try
orbitdelay=1000 with showdot=b/20 to get a feel for how the showdot
triangle works.
ASPECTDRIFT=<nn>
When zooming in or out, the aspect ratio (the width to height ratio) can
change slightly due to rounding and the noncontinuous nature of pixels.
If the aspect changes by a factor less than <nn>, then the aspect is set
to it's normal value, making the center-mag Xmagfactor parameter equal
to 1. (see CENTER-MAG above.) The default is 0.01. A larger value
adjusts more often. A value of 0 does no adjustment at all.