PROJECT(1)
NAME
project - project a set of solar images using a fixed map-
ping, with optional corrections for observer-dependent frame
SYNOPSIS
project [-cflorv] [argument= value ...]
DESCRIPTION
project maps a series of solar images from the observer
coordinate frame according to a specified map projection,
scale, location, and orientation. Carrington heliographic
coordinates are used. The output data series has the same
structure as the input data series. Running project without
observer-dependent corrections should be equivalent to run-
ning track_region with similar options and the Carrington
rate as the tracking rate on the same data, except that the
output series is more similar in structure to the input
series. With the cylindrical equal-area projection and
corresponding corrections it should also be equivalent to
v2helio without apodization.
The input data series is normally assumned to be continuous,
so if an image selection range is made (...,series:XXX[I-
J],sel:[M-N]) the first selector (M)is assumed to apply only
to the first data set (#I) and the last selector (N)to apply
only to the last data set (#J); all intervening images are
accepted. The -c flag forces the image selection to apply
independently to each data set in the series.
Various flags are used to force observer corrections, assum-
ing the observable is the Doppler signal. The -f flag
`corrects' for foreshortening of observables that are
assumed to be the radial components of a vector field. The
-l flag corrects for the Doppler limb effect, using coeffi-
cients a0 = 0 m/s, a1 = -500.0, a2 = 1025.0 in a power law
expansion in (1 - mu). The -o flag removes the component of
observer orbital velocity in the line-of-sight to each pixel
from the Doppler signal. The -r flag removes the line-of-
sight component of solar rotation from the Doppler signal,
using the Snodgrass coefficients for the standard law of
photospheric differential rotation: a0 = 2.8363991
microrad/sec, a1 = -0.3441, and a2 = -0.5037.
As usual the -v flag puts the module in verbose mode, echo-
ing various tidbits of information as it proceeds.
ARGUMENTS
in=Dataset
The input dataset name. The input dataset is expected
to be a series of calibrated images of all or part of
the solar disc in a "plate" coordinate system. The
dataset is assumed to include in its ancillary data the
parameters required for heliographic mapping, namely
the observation time and heliographic location. MDI
level 0 and level 1 data (in cropped and/or binned
one-dimensional lists) are acceptable. NO DEFAULT
out=Dataset
The output dataset name. NO DEFAULT
lat=real The heliographic latitude (in degrees)
of the center of the mapped images.
Default is center-of-disc latitude of
first image in input series.
lon=real The heliographic longitude (in degrees)
of the center of the mapped images.
Default is center-of-disc longitude of
first image in input series.
scale=real Scale of maps (in heliographic degrees /
pixel) at a location appropriate for the
selected mapping option, usually the
center of the map; a 0 value implies
autoscaling to best scale of (each)
image. Typical values would be about
0.057 * resolution [arcsec / pixel] for
solar radii of 1000 arcsec, or about
0.12 -- 0.125 for SOI full-disc images
(or HiDHN or HLH or TON images).
Default: 0.0 (autoscaling)
cols=int
rows=int The desired number of columns (rows) in
the mapped images; if non-zero, each
over-rides the corresponding auto-scaled
dimension appropriate to the radius
parameter (see below). Defaults: 0
radius=real The desired minimum radius of the maps,
in heliographic degrees. This is
advisory only; if used, the maps will be
squares of length equal to the smallest
power of two at the chosen map scale
necessary to include the minimum radius,
unless over-ridden by the rows and/or
cols arguments. For a typical scale of
0.12, a radius of about 15 deg
corresponds to a 128*128 map. If both
rows and cols are non-zero, this argu-
ment is ignored.
map=string Mapping option: recognized values are
"rectangular", "Postels", "gnomonic",
"stereographic", "orthographic", "Lam-
bert", "cyleqa", "sineqa", and "Merca-
tor". Default: "orthographic".
map_pa=real Position angle of the north direction on
the output image, measured positive
counterclockwise from the column direc-
tion, in degrees. Default: 0.0
grid=real If non-zero, the mapped data will be
overlain with a grid of latitude and
longitude lines at spacings of the grid
value in degrees (and thickness 1% of
the spacing); the grid line values are
NaN's where there would be data, 0.0
where there would be none. Default:
0.0.
crop=real If given, force image data beyond this
distance from the plate center (in pix-
els) to be ignored. Default: Not Speci-
fied
xscale=real
yscale=real The horizontal and vertical scale of
each image, both in arcsec / pixel, to
be used in the absence of appropriate
keywords in the data or to explicitly
override the values in the data. The
image header values are used if the
specified scale is 0.0. Defaults: 0.0
(use image header information)
xc=float
yc=float If non-zero, specify the coordinates of
the solar disc center of each image,
overriding whatever the appropriate data
keywords provide. The locations are
assumed to be specified in units of
image pixels measured from (0, 0) at the
center of the first image pixel.
Defaults: 0.0 (use image header informa-
tion)
img_pa=real If given, the constant position angle of
solar north to be assumed in the input
data, overriding the data header values.
Measured positive counterclockwise, in
degrees. Default: Not Specified
solar_radius=float If non-zero, specifies the constant true
semi-diameter of the solar image in pix-
els, overriding the value supplied by
the appropriate data keyword for each
image. Default: 0.0 (use image header
information)
bscale=float If non-zero, specifies the scaling to be
applied to FITS output as shorts; a zero
value implies FITS output as floats.
Default: 1.0
bzero=float Specifies the zero offset to be applied
to scaled FITS output as shorts; ignored
if bscale is zero. Default: 0.0
EXAMPLES
FILES
SEE ALSO
track_region(1), v2helio(1), cartography(3)
DIAGNOSTICS
soi_errno is returned and also set as the abortflg value in
the results keylist.
BUGS
It is not currently possible to remap previously projected
data with another mapping; it should be.
No checking is done for the observable; it is assumed to be
Doppler shift when the various corrections are applied.
Limb darkening corrections should be available as an option
for photometric data.
The values of the coefficients of the expansion terms in the
corrections should be arguments to the module rather than
hard-coded.
Project is pronounced with the emphasis on the 2nd syllable;
the name conflicts with that of a program in the rdb
library.
AUTHOR
Rick Bogart
HISTORY
2000.08.29 SOI Version 4.8