; CNTR ;--------------------------------------------------------------- ;! generate a contour plot file or TV plot from an image ;# Task Plot TV ;----------------------------------------------------------------------- ;; Copyright (C) 1995, 2002, 2009, 2011 ;; Associated Universities, Inc. Washington DC, USA. ;; ;; This program is free software; you can redistribute it and/or ;; modify it under the terms of the GNU General Public License as ;; published by the Free Software Foundation; either version 2 of ;; the License, or (at your option) any later version. ;; ;; This program is distributed in the hope that it will be useful, ;; but WITHOUT ANY WARRANTY; without even the implied warranty of ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the ;; GNU General Public License for more details. ;; ;; You should have received a copy of the GNU General Public ;; License along with this program; if not, write to the Free ;; Software Foundation, Inc., 675 Massachusetts Ave, Cambridge, ;; MA 02139, USA. ;; ;; Correspondence concerning AIPS should be addressed as follows: ;; Internet email: aipsmail@nrao.edu. ;; Postal address: AIPS Project Office ;; National Radio Astronomy Observatory ;; 520 Edgemont Road ;; Charlottesville, VA 22903-2475 USA ;----------------------------------------------------------------------- CNTR LLLLLLLLLLLLUUUUUUUUUUUU CCCCCCCCCCCCCCCCCCCCCCCCCCCCC CNTR: Task to generate a contour plot as TV image or plot file USERID -32000.0 32000.0 User ID. ignored INNAME Image name(name). INCLASS Image name(class). INSEQ 0.0 9999.0 Image name(seq. #). 0=>high INDISK Disk drive #. 0=>any BLC 0.0 4096.0 Bottom left corner of image 0=>entire image TRC 0.0 4096.0 Top right corner of image 0=>entire image XYRATIO 0.0 10.0 X to Y axis plot ratio. 0=> header inc or window ratio LTYPE -10.0 10.0 Type of labeling: 1 border, 2 no ticks, 3 standard, 4 rel to center, 5 rel to subim cen 6 pixels, 7-10 as 3-6 with only tick labels <0 -> no date/time PLEV -99.0 100.0 Percent of peak for levs. CLEV Absolute value for levs (used only if PLEV = 0). LEVS -9999.0 99999.0 Contour levels (up to 30). DOCIRCLE -1.0 1.0 > 0 => extend ticks to form coordinate grid STVERS -1.0 46655.0 STar file version number. STFACTOR -9999.0 9999.0 Scale star sizes: 0 => none. > 0 crosses with no labels < 0 crosses with labels DOTV -1.0 1.0 > 0 Do plot on the TV, else make a plot file GRCHAN 0.0 8.0 Graphics channel 0 => 1. TVCORN 0.0 2048.0 TV pixel location of bottom left corner of image 0=> self scale, non 0 => pixel scale. ---------------------------------------------------------------- CNTR Type: Task Use: CNTR will write commands to a plot file for the execution of a contour plot for an image. CNTR supports TELL operations QUIT and ABOR only. Adverbs: USERID......The ID of the owner of the image. Ignored. INNAME......Image name (name). Standard defaults. INCLASS.....Image name (class). Standard defaults. INSEQ.......Image name (seq. #). 0 => highest. INDISK......Disk unit #. 0 => any. BLC.........Bottom Left Corner of image to contour. (0,0) means (1,1). TRC.........Top Right Corner of image to contour. (0,0) means top right corner of map. XYRATIO.....The ratio of the X-axis to Y-axis pixel separations. 0 => X to Y inc. in map header if related, else Y to X window LTYPE.......Labelling type: 1 = border, 2 = no ticks, 3 or 7 = standard, 4 or 8 = relative to ref. pixel, 5 or 9 = relative to subimage (BLC, TRC) center, 6 or 10 = pixels. 7-10 all labels other than tick numbers and axis type are omitted. Less than 0 is the same except that the plot file version number and create time are omitted. PLEV........Percent of peak for the contour increment. If PLEV and CLEV are zero, 10 is used. CLEV........Image intensity value for the contour increment. Used only if PLEV = 0. LEVS........Contour levels in units of the increment. The levels must be in ascending order and a maximum of 30 levels are permitted. 0 => -10,-9, -8,-7,-6,-5,-4,-3,-2,-1,1,2,3,4,5,6,7,8,9,10,0 DOCIRCLE....False (<= 0) means that tick marks are short lines extending inward from the plot borders. True (>0) requests that a full coordinate grid be drawn. STVERS......Version number of ST (star position) file to be used to plot star positions as plus signs. 0 => highest, < 0 => no star positions plotted STFACTOR....Scale factor used to multiply star sizes in file for plotting. > 0 => scale star size = 0 => don't plot stars. < 0 => scale by abs(STFACTOR) and show any star label DOTV........> 0 => plot directly on the TV device, otherwise make a plot file for later display on one or more devices (including the TV if desired). GRCHAN......Graphics channel (1 - 7) to use for line drawing. 0 => use multiple graphics planes for the various parts of the graphical drawing. TVCORN......TV pixel location (X,Y) where the bottom left- corner of the plot is to be placed. If either is zero, use the largest possible self scaling, else use pixel scaling with specified origin on the TV. ---------------------------------------------------------------- CNTR: Task to create a contour-plot extension file for an image RELATED PROGRAMS: PCNTR, KNTR, PRTPL, TKPL, TVPL, TVWIN PURPOSE CNTR generates a plot extension file containing an intensity contour plot, its border, and labels. The window limits and contour levels are recorded in the header of the plot file, and may be listed on your terminal with EXTLIST. CNTR indicates positive and negative contour values by continuous and broken lines, respectively. The plot itself may be displayed on a printer, TEK screen, or TV graphics channel by the tasks PRTPL, TKPL, or TVPL respectively. COMMENTS Contour plots are often more useful for quantitative image analysis than gray-scale or profile plots, and most maps are published in the form of contour plots. By suitable choice of contour levels, a contour plot can give a quantitative display of all features in an image with very large dynamic range. The contour plot of a map will be messy if contours are plotted at levels below about 3 times the rms noise. Contour plots tend to emphasize gradients in intensity. The contour plot of a complex image, especially one with local minima, can therefore be confusing. Note that a local (but non-negative) minimum will be indicated by a closed continuous contour, so that it is indistinguishable from a maximum. Also, the simple interpolation routine used by CNTR may produce jagged "staircase" contours. This problem can be minimized by interpolating the image with the task GEOM. BLC, TRC: A convenient way to select the plot corners is to display the image on the TV and set the rectangular boundary of the subimage to be plotted with the verb TVWIN. LEVS: Nonzero elements LEVS(I) in this 30-element vector specify the contour levels LEVS(I)*PLEV or LEVS(I)*CLEV to be plotted. They must be specified in increasing order and lie within the range -9999.0 to +99999.0. It is easy to specify a large number of LEVS values with a FOR loop. For example, the statement: FOR I=1 TO 20;LEVS(I)=2**((I-1)/2.);END ; LEVS(21)=0. yields successive contours separated by factors of 2**.5 If you request more than one negative level via a statement of the form LEVS = a , b , c , d , e , f , g you must use commas between the negative levels. Otherwise, the minus sign(s) will be treated as subtraction symbols by POPS and the desired levels will be combined into a single negative level. LTYPE: 1=> unlabeled rectangular border 2=> rectangular border plus labels (image name, center position, etc.). Beware that the PEAK FLUX label gives the peak flux in the whole image, not that in the subimage plotted. 3=> rectangular border, labels, and border tick marks indicating absolute coordinates (r.a., decl., etc.) 4=> rectangular border, labels, and border tick marks indicating coordinates relative to the coordinates of the image reference pixel 5=> rectangular border, labels, and border tick marks indicating coordinates relative to the center of the subimage plotted 6=> rectangular border, labels, and border tick marks indicating image pixel numbers 7-10 => like 3-6 but the extra labels are omitted. An LTYPE which is < 0 is used, in absolute value, to control the labeling as listed above and specifies that the "PLOT FILE VERSION n CREATED date time" string is not placed on the plot. XYRATIO: XYRATIO can be used to change the plot aspect ratio. Values >1 stretch the X-axis, values <1 compress it. DISPLAYING THE PLOT: On termination of CNTR, the messiness of the plot can be judged by looking at the message on your monitor: GFINIS: NUMBER OF RECORDS GUESSED NNN USED MMM If MMM is much greater than 200, the plot will be complicated. If this happens when you thought you were contouring a simple small field, you have probably set the levels too low (or have specified the contouring window incorrectly). You may wish to check your inputs before trying to display the plot. It is always worth using TKPL or TVPL to preview a new plot before routing it to the slower PRTPL, unless you are very sure that your input parameters were well chosen. STFACTOR: You can use STarFACTOR to add crosses or other symbols to your plot to denote the postions of stars or other objects. First you must read the postions into a ST table using STARS. Then set INVER to the table version number. You can scale the sizes of the crosses be setting STFACTOR > 0. Set STFACTOR to 1.0 for no scaling (use the star sizes in the ST table). You can label the crosses with a character string to help identify them by setting STFACTOR < 0. The label is the text string entered when creating the ST table. The star sizes in this case will be scaled by ABS(STFACTOR). Note that you can also rotate the crosses through an angle by specifying a positon angle when you create the ST table in STARS (see STARS for more information).