firandom - generates artificial object lists and simulated
images
firandom [options] [-o|--output
<output>]
The main purpose of this program is to generate artificial object
lists and/or artificial (astronomical) images.
- -l, --list
<list>
- Specifications for object list. The "list" parameter should be a
set of comma separated tags, which can either be a value declaration or a
repeat count followed by an expression between square brackets giving
specifications for individual objects to be added to the list, also in the
form of value declaration. The value declaration has the sintax of
<variable>=<value>, where the variables can be the
following:
- f
- full width at half magnitude (FWHM) of the stellar profiles to be
created
- e
- ellipticity of the stellar profiles
- p
- position angle of the stellar profiles
- s
- sigma parameter for the stellar profile (FWHM is roughly 2.35 *
sigma)
- d
- delta (plus-shaped deviance) parameter for the stellar profile
- k
- kappa (cross-shaped deviance) parameter for the stellar profile
- S
- Gaussian momenum (a.k.a. profile sharpness parameter) for the stellar
profile (S=1/sigma^2)
- D
- plus-shaped momentum for the stellar profile
- K
- cross-shaped momentum for the stellar profile
- x
- normalized X coordinate of the profile centroid (using the standard
normalization)
- X
- absolute X coordinate of the profile centroid
- y
- normalized y coordinate of the profile centroid (using the standard
normalization)
- Y
- absolute Y coordinate of the profile centroid
- m
- magnitude of the stellar object
- i
- flux of the stellar object
One can use only one of the three equivalent set of profile shape
parameters (i.e. f/e/p, s/d/k or S/D/K). See some more detailed
documentation about these parameters. In the expressions which are in the
square brackets, one can use arbitrary arithmetic expressions, using the
standard basic arithmetical operators, elementary functions and the
functions r(lo,hi) and g(mean,sigma) which results an uniformly distrbuted
random number between "lo" and "hi" and a Gaussian
random number with the specified "mean" and "sigma"
(standard deviation), respectively. In the expressions for magnitude or
intensity, one can use the previously defined values for the centroid
coordinates too. The variable "n" is increased between 0 and the
repeat count during the evaluation of the square bracket expressions.
- --output-list
<list file>
- Name of the list file where the object list created by the subsequent
--list options are saved.
- --fep,
--fep-output
- Save the shape parameters as FWHM, ellipticity and position angle to the
output list file.
- --sdk,
--sdk-output
- Save the shape parameters as sigma, delta and kappa to the output list
file.
- --SDK,
--SDK-output
- Save the shape parameters as Gaussian momenta to the output list
file.
- -s, --size <sx>,<sy>
- Size of the image to be created.
- -b, --bitpix
<bitpix>
- Standard FITS output bitpix value.
- -D, --data <spec>
- Output pixel data format specification.
- -m, --sky <sky>
- Sky (background level) for the image. This can be either a constant or an
arbitrary function of the x, y, X and Y coordinates (see above) for a
backgroud with shows systematic variations. One can use the previously
discussed r(lo,hi) and g(mean,sigma) functions, in order to add some sort
of noise to the background.
- -d, --sky-noise <noise>
- Additional Gaussian noise, equivalent to the term
"+g(<noise>,0)" added after the background level
expression.
- --photon-noise,
--no-photon-noise
- Emulate or disable the effect of photon noise on the individual stellar
objects.
- -l, --list
<list>
- Specifications for object list (see above).
- -L, --input-list
<list file>
- Name of the input list file from which the coordinates, shape parameters
and intensities are read for the individual objects.
- --col-xy
<colx>,<coly>
- Column indices for X and Y (absolute) centroid coordinates.
- --col-flux <flux
column>
- Column index for flux (intensity).
- --col-mag
<magnitude column>
- Column index for astronomical magnitude, see also --mag-flux.
- --col-shape
<profile width>,[<profile shape 1>,<profile shape
2>]
- Column indices for stellar profile parameters. Either 1 or 3 columns
should be specified following this command line switch. One shape
parameter is interpreted as a profile size parameter where the 2
additional (optional) shape parameters describe the deviation from the
symmetric profile. See also options --fep, --sdk or
--SDK for more details.
- --fep,
--fep-input
- Interpret the shape parameters read from the input list file as FWHM,
ellipticity and position angle.
- --sdk,
--sdk-input
- Interpret the shape parameters read from the input list file as the sigma,
delta and kappa parameters.
- --SDK,
--SDK-input
- Interpret the shape parameters read from the input list file as the
Gaussian momenta parameters.
- -S, --input-sky, --input-background,
--input-image <sky list file>
- Name of the input file containing the sky level. This file should contain
at least three columns: the two pixel coordinates and the sky vaule. See
also --col-pixel and --col-value.
- --col-pixel
<colx>,<coly>
- Column indices for X and Y (absolute) pixel coordinates.
- --col-value <sky
value column>
- Column index for sky value (intensity).
- --mag-flux
<mag>,<flux>
- Magnitude - flux conversion level. The specified magnitude will be
equivalent to the specified flux level.
- --integral,
--no-monte-carlo
- Draw the stellar profiles to the image using exact integration.
- --monte-carlo,
--no-integral
- Draw the stellar profiles to the image using a Monte-Carlo way. Note that
using this Monte-Carlo method without additional photon noise emulation
would result assymetric stellar profiles even when the profile would be
symmetric. Use this option only when the --photon-noise option is
also used, therefore the profiles are strained with photon noise
either.
- --noise-suppression
<level>
- If the profiles are drawn using exact integration, the profiles would be
infintely large since an analytical Gaussian profile is positive on the
whole image domain. In order to limit the integration boundaries, this
level limits the size of the integration domain, by the following way. The
expected level of the objects's own photon noise at the edges of the
integration domain is smaller by this factor at least than the flux level.
Higher suppression level results larger integration domain. In the case of
additional photon noise, the default value of 10000.0 is satisfactory. For
images with no photon noise, this level should be increased
appropriately.
- --quantize,
--no-quantize
- Quantize the output images to integers or not. Note that altering this
option yields somehow the same as when the bitpix value is altered.
- --adus,
--no-electrons
- Use the input fluxes as ADUs instead of electrons (default).
- --electrons,
--no-adus
- Use the input fluxes as electrons insead of ADUs.
- -g, --gain
<gain>
- Electron/ADU ratio (gain).
- --seed
<seed>|auto
- Generic random seed for `firandom`. A literal "auto" argument
yields a random seed derived from random sources available on the
architecture (/dev/urandom, current time).
- --seed-noise
<seed>|auto
- Specific random seed for creating background noise.
- --seed-spatial
<seed>|auto
- Specific random seed for creating random spatial coordinates, i.e. the
random seed for functions in the --list arguments.
- --seed-photon
<seed>|auto
- Specific random seed for photon noise.
- --list <list>
--output-list <list file>
- This combination creates only a list file based on the --list
arguments.
- --input-list <list
file> --output-list <list file>
- This combination just filters and copies the relevant contents from the
input list to the output list. The shape parameters might be converted,
for example --SDK-input --fep-output would convert Gaussian
momenta to FWHM, ellipticity and position angle.
- --list <list>
--output <output image> [--output-list <list
file>]
- This combination creates an artificial list of sources and then creates an
artificial image with this newly created set of objects. By default, the
list itself (incl. the centroid coordinates, shape parameters and
intensities) is not saved unless an output list file is given.
- --input-list
<list file> --list <list>
- This combination is invalid, the centroid list must either be read from a
file or created by the program invocation but lists cannot be merged this
way. In such case, save the object list to a separete file and merge the
files using standard tools.
Report bugs to <apal@szofi.net>, see also
https://fitsh.net/.
Copyright © 1996, 2002, 2004-2008, 2010-2016, 2018-2020;
Pal, Andras <apal@szofi.net>