mollview


This IDL facility provides a means to visualise a full sky Mollweide projection of HEALPix and COBE Quad-Cube maps in an IDL environment. It also offers the possibility to generate gif and postscript images of the projected map.


Location in HEALPix directory tree: src/idl/visu/mollview.pro


FORMAT

IDL> MOLLVIEW, File, [Select, ] [COLT=, ... ... UNITS=, XPOS=, YPOS= ]

Routine codes :
C : cartview, G : gnomview, M : mollview, O : orthview, all : all of them

Qualifiers can take a range of values.
Keywords are switches, they are either present (or set to 1) or absent (or set to 0).

QUALIFIERS


name routines description
File all by default : name of a FITS file containing the healpix map in an extension or in the image field
if Online is set : name of a variable containing the healpix map
if Save is set : name of an IDL saveset file containing the healpix map stored under the variable data
(default : none)
Select all column of the BIN FITS table to be plotted, can be either
- a name : value given in TTYPEi of the FITS file
NOT case sensitive and can be truncated,
(only letters, digits and underscore are valid)
- an integer : number i of the column containing the data, starting with 1
default:1 (see the Examples below)
name routines description
CHARSIZE= all overall multiplicative factor applied to the size of all ; characters appearing on the plot default:1.0
COLT= all color table number, in [0,40] default:33 (Blue-Red)
COORD= all vector with 1 or 2 elements describing the coordinate system of the map; either
- 'C' or 'Q' : Celestial2000 = eQuatorial,
- 'E' : Ecliptic,
- 'G' : Galactic
if coord = ['x','y'] the map is rotated from system 'x' to system 'y'
if coord = ['y'] the map is rotated to coordinate system 'y' (with the original system assumed to be Galactic unless indicated otherwise in the input file)
see also:Rot
FACTOR= all multiplicative factor to be applied to the data
the data plotted is of the form Factor*(data + Offset)
see also:: Offset, LOG
default:1.0
FITS= -G- string containing the name of an output fits file with the rectangular map in the primary image
if set to 1 : output the plot in plot_gnomonic.fits
if set to a file name : output the plot in that file
default:0: no .FITS done
GAL_CUT= -M- (positive float) specifies the symmetric galactic cut in degrees outside of which the monopole and/or dipole fitting is done default:0: monopole and dipole fit done on the whole sky (see also:: No_dipole, No_monopole)
GIF= all string containing the name of a .GIF output
if set to 1 : output the plot in plot_[projection].gif
if set to a file name : output the plot in that file
Please note that the resulting GIF image might not always look as excpected. The reason for this is problems with 'backing store' in the IDL-routine TVRD. Please read the IDL documentation for more information.
default:no .GIF done
see also:Crop, Png, Ps and Preview
name routines description
     
GRATICULE= all if set, puts a graticule (ie, longitude and latitude grid) in the output astrophysical coordinates with delta_long = delta_lat = gdef degrees
if set to a scalar x > gmin then delta_long = delta_lat = x
if set to [x,y] with x, y > gmin then delta_long = x and delta_lat = y
cartview : gdef = 45, gmin = 0
gnomview : gdef = 5, gmin = 0
mollview : gdef = 45, gmin = 10
orthview : gdef = 45, gmin = 10
Note that the graticule will rotate with the sphere is Rot is set. To outline only the equator set graticule=[360,90].
default:0 [no graticule]
see also:Igraticule, Rot, Coord
HXSIZE= all horizontal dimension (in cm) of the Postscript printout
default:26 cm $ \simeq$ 10 in
see also:Pxsize
IGRATICULE= all if set, puts a graticule (ie, longitude and latitude grid) in the input astrophysical coordinates. See Graticule for conventions and details. If both Graticule and Igraticule are set, the latter will be represented with dashes.
default:0 [no graticule]
see also:Graticule, Rot, Coord
MAX= all Set the maximum value for the plotted signal
default:is to use the actual signal maximum.
MIN= all Set the minimum value for the plotted signal
default:is to use the actual signal minimum.
OFFSET= all additive factor to be applied to the data
the data plotted is of the form Factor*(data + Offset) can be used together with LOG
see also : Offset, LOG
default:0.0

name routines description
OUTLINE= all structure containing the description of one (or several) outline(s) to be overplot on the final map.
For each contour, the corresponding (sub)structure should contain the following fields :
- 'COORD' coordinate system (either, 'C', 'G', or 'E') of the contour
- 'RA' RA/longitude coordinates of the contour vertices (array)
- 'DEC' Dec/latitude coordinates of the contour vertices (array)
- 'LINESTYLE' (optional) +2 : black dashes, +1 : black dots, 0 : black solid (default), -1 : black dots on white bg, -2 : black dashes on white bg
Notes: the vertices are connected by segments of geodesics. To obtain a better looking outline, increase the number of vertices provided. The outline does not have to be closed. The procedure will NOT attempt to close the outline.
see also:Coord, Graticule
PNG= all string containing the name of a .PNG output
if set to 1 : output the plot in plot_[projection].png
if set to a file name : output the plot in that file
Please note that the resulting PNG image might not always look as excpected. The reason for this is problems with 'backing store' in the IDL-routine TVRD. Please read the IDL documentation for more information.
default:no .PNG done
see also:Crop, Gif, Ps and Preview
name routines description
POLARIZATION= all if set to
* 0
no polarization information is plotted.
* 1
the AMPLITUDE P = $ \sqrt{(}$U2 + Q2) of the polarisation is plotted (as long as the input data contains polarisation information (ie, Stokes parameter Q and U for each pixel))
* 2
the ANGLE $ \phi$ = tan-1(U/Q)/2 of the polarisation is plotted
Note: the angles are color coded with a fixed color table (independent of Colt)
* 3
-the temperature is color coded (with a color table defined by Colt)
-and the polarisation is overplot as headless VECTORS
default:0
Note: The representation of the polarization direction (options 2 and 3 above), include the effects of the rotations and/or changes or astronomical coordinates (controlled by ROT and COORD respectively) but do not include the effects of the distortions induced by the projection from the sphere to the plan. Because the polarization usually has more power at small scales, it must generally be represented on maps of small patches of the sky to remain legible, in which case the projection-induced distortions are small.
PS= all if set to 0 : no postscript output
if set to 1 : output the plot in plot_cartesian, plot_gnomic.ps, plot_mollweide.ps or plot_orthographic respectively
if set to a file name : output the plot in that file
default:0
see also:Preview, Gif, Png
PXSIZE= all set the number of horizontal screen_pixels or postscript_color_dots of the plot (useful for high definition color printer)
default:800 (Mollview and full sky Orthview), 600 (half sky Orthview), 500 (Cartview and Gnomonic)
PYSIZE= CG- set the number of vertical screen_pixels or postscript_color_dots of the plot
default:Pxsize
name routines description
RESO_ARCMIN= -G- size of screen_pixels or postscript_color_dots in arcmin
default:1.5
ROT= all vector with 1, 2 or 3 elements specifing the rotation angles in DEGREES to apply to the map in the 'output' coordinate system (see Coord) = ( lon0, [lat0, rat0])
lon0 : longitude of the point to be put at the center of the plot the longitude increases Eastward, ie to the left of the plot default:0
lat0 : latitude of the point to be put at the center of the plot default:0
rot0 : anti clockwise rotation to apply to the sky around the center (lon0, lat0) before projecting default:0
SUBTITLE= all String containing the subtitle to the plot
see also:Titleplot
TITLEPLOT= all String containing the title of the plot, if not set the title will be File
see also:Subtitle
UNITS= all String containing the units, to be put on the right hand side of the color bar, overrides the value read from the input file, if any
see also:Nobar, Nolabels
XPOS= all The X position on the screen of the lower left corner of the window, in device coordinate
YPOS= all The Y position on the screen of the lower left corner of the window, in device coordinate

KEYWORDS


name routines description
CROP= all if set the GIF/PNG file only contains the map and no title, color bar, ...
see also:Gif, Png
FLIP= all if set the longitude increases to the right, whereas by default (astronomical convention) it increases towards the left
name routines description
HALF_SKY= --O if set, only shows only one half of the sky (centered on (0,0) or on the location parametrized by Rot) instead of the full sky
HELP= all if set, the routine header is printed (by doc_library) and nothing else is done
HIST_EQUAL= all if set, uses a histogram equalized color mapping (useful for non gaussian data field) default:uses linear color mapping and puts the level 0 in the middle of the color scale (ie, green for Blue-Red) unless Min and Max are not symmetric
see also:Log
LOG= all display the log of map. This is intended for application to positive definite maps only, eg. Galactic foreground emission templates
see also:Hist_Equal, Offset
NESTED= all specify that the online file is ordered in the nested scheme
NO_DIPOLE= -MO if set (and Gal_cut is not set) the best fit monopole *and* dipole over all valid pixels are removed;
if Gal_cut is set to b > 0, the best monopole and dipole fit is performed on all valid pixels with |galactic latitude| > b (in deg) and is removed from all valid pixels
default:0 (no monopole or dipole removal)
can NOT be used together with No_monopole
see also:Gal_cut, No_monopole
NO_MONOPOLE= -MO if set (and Gal_cut is not set) the best fit monopole over all valid pixels is removed;
if Gal_cut is set to b > 0, the best monopole fit is performed on all valid pixels with |galactic latitude| > b (in deg) and is removed from all valid pixels
default:0 (no monopole removal)
can NOT be used together with No_dipole
see also:Gal_cut, No_dipole
NOBAR= all if set, color bar is not present
NOLABELS= all if set, color bar labels (min and max) are not present, default: labels are present
NOPOSITION= -G- if set, the astronomical location of the map central point is not indicated
name routines description
ONLINE= all if set, you can put directly a HEALPix vector or an IDL structure on File (useful when the data to be plotted are already available on line) N.B. : the content of File is NOT altered in the process,
can not be used with /SAVE
PREVIEW= all if set, there is a 'ghostview' preview of the postscript file or a 'xv' preview of the gif file
see also:Gif, Png and Ps
SAVE= all if set, assumes that File is in IDL saveset format, the variable saved should be DATA
can not be used with /ONLINE


DESCRIPTION


mollview reads in a HEALPix sky map in FITS format and generates a Mollweide projection of it, that can be visualized on the screen or exported in a GIF or Postscript file. mollview allows the selection of the coordinate system, map size, color table, color bar inclusion, linear or log scaling, histogram equalised color scaling, maximum and minimum range for the plot, plot-title etc. It also allows the representation of the polarization field.

Figure 1: Figures produced by cartview, gnomview, mollview and orthview, see respective routine documentation for details.
\begin{figure}\centerline{
\hbox{
\psfig{file=plot_cartesian.ps,width=3.5in,angl...
...le={90}}
\psfig{file=plot_orthographic.ps,width=4.5in,angle={90}}
}}\end{figure}


RELATED ROUTINES

This section lists the routines related to mollview


idl
version 5.0 or more is necessary to run mollview
ghostview
ghostview or a similar facility is required to view the Postscript image generated by mollview.
xv
xv or a similar facility is required to view the GIF/PNG image generated by mollview(a browser can also be used).
synfast
This HEALPix facility will generate the FITS format sky map to be input to mollview.
cartview
IDL facility to generate a Cartesian projection of a HEALPix map.
cartcursor
interactive cursor to be used with cartview
gnomview
IDL facility to generate a gnomonic projection of a HEALPix map.
gnomcursor
interactive cursor to be used with gnomview
mollview
IDL facility to generate a Mollweide projection of a HEALPix map.
mollcursor
interactive cursor to be used with mollview
orthview
IDL facility to generate an orthographic projection of a HEALPix map.
orthcursor
interactive cursor to be used with orthview


EXAMPLE # 1:

mollview, `planck100GHZ-LFI.fits', min=-100, max=100, /graticule, $
  title='Simulated Planck LFI Sky Map at 100GHz'

mollview reads in the map ` planck100GHZ-LFI.fits' and generates an output image in which the temperature scale has been set to lie between ± 100 ($ \mu$K), a graticule with a 45 degree step in longitude and latitude is drawn, and the title ` Simulated Planck LFI Sky Map at 100GHz' appended to the image.


EXAMPLE # 2:

map

= findgen(48)
triangle = create_struct('coord','G','ra',[0,80,0],'dec',[40,45,65])
mollview, map,/online,res=25,graticule=[45,30],rot=[10,20,30],$
  title='Mollweide projection',subtitle='mollview', $
  outline=triangle

makes a Mollweide projection of map (see Figure 1c on page [*]) after an arbitrary rotation, with a graticule grid (with a 45o step in longitude and 30o in latitude) and an arbitrary triangular outline

Eric Hivon 2003-02-07