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Vector Overlay Function (vector)

Description:U & V vectors stored in ASCII or HDF files can be overlaid as graphics on images which are regular grids (i.e. in Equi-distant rectangular projection, or IDL's Cylindrical Projection).  The u & v data also must be stored on regular grids.

Note:  You will achieve better vector resolution if outputting to a postscript file.  The vectors are stored as annotation objects and will be redrawn at postscript resolution.

[Interactive mode][Command mode]


Command mode:

Usage: vector, fbuf=fbuf, uvbands=uvbands, uvals=u, vvals=v, lats=lats, lons=lons, fname=fname, skiplines=skiplines, cols=cols, slopes=slopes, intcpts=intcpts, rate=rate, color=color, mlinethick=mlinethick, mlinestyle=mlinestyle, missing=missing, length=length, print=print, help=help

Examples:

  1. Load a SeaWiFS SMI file and u and v winds from an ancillary MET file.  Display the SMI file and overlay vectors from the MET file using the z_wind as the u component and the m_wind as the v component:
  2. seadisp
    load, '$SDSDEMO/L3_daily1_smi_CHLO_mn.hdf', xsample=8, ysample=8,  /loadpal
    load, '$SDSDEMO/ANC1.MET1', prod_name=['z_wind','m_wind'], ftype='HDF',xsample=10, ysample=10
    display, band_no=1, fbuf=1
    vector, uvbands=[2,3], color=6
  3. Load a SeaWiFS SMI file and u and v winds from columns 4 & 1 from an ASCII file.  Columns 2 and 3 contain latitude and longitude:
  4. seadisp
    load, '$SDSDEMO/L3_daily1_smi_CHLO_mn.hdf', xsample=8, ysample=8, /loadpal
    display, band_no=1, fbuf=1
    vector, fname='winds.asc', cols=[2,3,4,1], skiplines=1
Input keywords:
fbuf The window number in which to overlay the vector graphics (default is the current window).
One of the following 3 methods must be used to specify the input u,v data (required)
U,V input from loaded bands uvbands - An array of two band numbers  containing the u and v data: [u band, v band].
U,V input from ASCII file
fname The file name of the input ASCII file containing the u and v data as well as the latitude & longitude information.
skiplines The number of header lines to skip in the ASCII file before reaching the column data.
cols An array of 4 elements containing the column numbers of the [latitude, longitude, u value, v value]
The following 2 keywords can be used to scale the ASCII column data if necessary
slopes An array of 4 elements containing the slopes to be used in scaling the latitude, longitude, u value and v values. The default is [1.0, 1.0, 1.0, 1.0].
intcpts An array of 4 elements containing the intercepts to be used in scaling the latitude, longitude, u value and v values. The default is [0.0, 0.0, 0.0, 0.0].
Direct U,V input as variables
uvals A 2-dimensional array containing the u data.
vvals A 2-dimensional array containing the v data.
lats A 2-dimensional array containing the latitude values corresponding to the u & v data.
lons A 2-dimensional array containing the longitude values corresponding the the u & v data.
rate Subsampling rate for u,v input.  (Default=1)

Vector Control Keywords:
color 1 to 7 of the SeaDAS graphics palette.  (Default=1).
mlinestyle 0 = solid  (Default)
1=dotted
2=dashes
3=dash-dot
4=dash 3 dot
5=long dashes 
mlinethick Line thickness. 1 to 10.  (Default=1)
missing Vectors of greater magnitude than this length will not be plotted.  The maximum length will print out for you to see.  Magnitudes are calculated as  the SQRT(u^2.0 + v^2.0).  (Default=1.0e30)
length The vector length factor.  The default of 1.0 will scale the vectors so that the longest vector is the length of a cell.

General Keywords:
help Print out help information.


Interactive mode:

Description:  Selecting Functions->Vector Overlay within the Display Window Widget will bring up the Vector Overlay Widget.

Action items:
Input source
Loaded Bands
  • U Band No. - The loaded band number containing the u data.
  • V Band No. - The loaded band number containing the v data.
  • ASCII Files (see the ASCII Input Widget)
    Input Sample Rate (see keyword rate in command mode)
    Vector Color (see keyword color in command mode)
    Line Thickness (see keyword mlinethick in command mode)
    Line Style (see keyword mlinestyle in command mode)
    Missing Length (see keyword missing in command mode)
    Length Factor (see keyword length in command mode)
    Go Generate vectors using the u and v data supplied and overlay as graphics on the window specified in fbuf.
    Help Display this help file in the user's HTML browser.
    Quit Exit the vector setup widget.


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    Authorized by: gene carl feldman

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    Updated: 15 December 2008