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snapsmooth - adaptive variable length smoothing
snapsmooth in=SnapShot(5)
-file
out=Image(5)
-file [parameter=value]
snapsmooth produces a binary
file specifying a smoothed image of an N-body snapshot in the xy plane,
with the smoothing length of each point determined by the distance to a
nearby neighbor and by user-specified parameters. The headline string of
the output file is an image of the parameter values and also shows the
number of particles that were smoothed.
snaprotate(1NEMO)
has to be used
first to image any other than a top-view.
snaptrim(1NEMO)
has to be used
first to produce an image of any snapshot other than the first in a file.
The following parameters are recognized in any order if the keyword
is also given
- in=SnapShot file
- input file, in snapshot(5NEMO)
format [no
default, reads first snapshot]
- out=Image file
- output file, in binary image(5NEMO)
format [no default].
- sl=real slc=real
- smoothing length will be (distance
to kth nearby-neighbor) * sl + slc. Note that slc is measured in pixels,
and is thus dependant on npix [default sl is 1, slc is 2.5% of npix]
- k=int
- the smoothing length will be a factor of the kth nearby-neighbor. The program
uses a two-D tree structure to store the points, and repeatedly finds the
point that encloses the smallest square around the target point, excluding
those it has found already until it has found k squares [default is 1].
- realnn=bool
- false for nearby neighbor approximation, true for nearest
neighbor (slower) [default false]. The nearby-neighbor approximation finds
the point that encloses the kth smallest square around the target point,
while the nearest neighbor algorothm takes the box found by the approximation,
enlarges by the amount necessary to enclose a circle inscribing the square,
sorts all of the points in the enlarged square by distance and returns
the kth point.
- every=int
- read every everyth from snapshot for smoothing
[default is 1]: this can help speed up processing of the image.
- npix=int
- the number of pixels to a side of the square onto which the program will
smooth the image. The program will scale the image onto the array without
distorting the image such that all the points will fit, with a margin for
spread due to smoothing [default is 100].
- sfunc=smoothing function name
- the smoothing function is either "gauss" or "spline" (a smooth finite-bounded
bell-shaped curve). The surface brightness of the image will be the total
mass of the image.
- gaussminval=real
- minimum value of gaussian (maximum 1.0
at origin) [default 0.01]
snapshot(5NEMO)
, snaprotate(1NEMO)
, ccddisplay(1NEMO)
Peter Wisnovsky
~/src/pswisnov/snapsmooth author’s original sources
xx-jun-87 Braught into system PSW
12-jul-88 small mods for new filestruct and history PJT
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