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#!N 
#!CDarkGreen #!N  #!Rpickin Using Pick #!N #!EC #!N 
#!N Picking consists of choosing a location on an object in 
an image using the mouse. A chosen location is called a 
"poke." Each poke may intersect the object in the image in 
one or more places (the intersections are called "picks") or may 
not intersect the object at all. For example, a poke on 
a spherical isosurface results in two "picks": one on the front 
of the sphere and one on the back. Picking differs from 
using probes, in which probes may be present anywhere in a 
3-dimensional space, while picks always exist on the surface of an 
object. #!N #!N After you execute a visual program and have 
an image in the Image window, you can modify the visual 
program to include a  #!F-adobe-times-bold-r-normal--18*   Pick #!EF tool from the  #!F-adobe-times-bold-r-normal--18*   
Special #!EF category. The Pick tool accepts input from the mouse 
and outputs a field that specifies the picked point or points. 
The "positions" component of this field identifies each picked point on 
the object in the image. The field can be used, for 
example, to identify all picked points with a glyph, or to 
start streamlines at each picked point. In addition, the field output 
by the Pick tool can be used by a user-written module 
to perform a variety of operations on the object in the 
image (e.g., coloring each picked object a particular color). IBM Visualization 
Data Explorer Programmer's Reference includes a sample module that uses the 
pick structure in this way. #!N #!N To use picking to 
select points on objects: #!N #!I0 #!N  #!F-adobe-times-medium-r-normal--18*   #!N #!N #!I30 
#!N 1. Execute a visual program to produce an image in 
the Image window. #!N #!I30 #!N 2. In the VPE, place 
one or more pick tools from the  #!F-adobe-times-bold-r-normal--18*   Special #!EF category 
in the visual program, connecting them to the tools for which 
you want to provide input. #!N #!N The pick icons are 
numbered as you place them on the canvas. For example, the 
first pick icon you place is labeled "Pick_1," the second "Pick_2," 
and so on. You can change the label of the icon 
by using its Configuration dialog box. #!N #!I30 #!N 3. In 
the  #!F-adobe-times-bold-r-normal--18*   View Control... #!EF dialog box, select  #!F-adobe-times-bold-r-normal--18*   Pick #!EF 
mode from the  #!F-adobe-times-bold-r-normal--18*   Mode #!EF option box or use the 
 #!F-adobe-times-bold-r-normal--18*   Ctrl+I #!EF accelerator key. The dialog box changes to add 
the Pick controls. #!N #!N Select the pick tool you want 
by choosing the  #!F-adobe-times-bold-r-normal--18*   Pick(s) #!EF option box. This opens an 
options menu with a list of the available picks from which 
to select. #!N #!I30 #!N 4. Select a point or points 
as input to the tool connected to the Pick icon. #!N 
#!N To choose a point, click on a point in the 
image. A small square box appears, marking the point. #!N #!I0 
#!N #!EF #!N Depending on whether you have the  #!F-adobe-times-bold-r-normal--18*   persistent 
#!EF parameter to the Pick tool set to 0 or 1, 
subsequent executions may or may not use the last pick point 
or points chosen. If  #!F-adobe-times-bold-r-normal--18*   persistent #!EF is set to 0, 
then pick points are not saved between executions; if  #!F-adobe-times-bold-r-normal--18*   persistent 
#!EF is set to 1, then pick points are saved between 
executions. Note: You can also enable Pick mode by using the 
 #!F-adobe-times-bold-r-normal--18*   intrctnMode #!EF parameter to the Image tool (see Image in 
IBM Visualization Data Explorer User's Reference). #!N #!N #!N  #!F-adobe-times-medium-i-normal--18*   Next 
Topic #!EF #!N #!N  #!Lall322,dxall323 h Undo, Redo, and Reset  #!EL  #!N  #!F-adobe-times-medium-i-normal--18*   #!N 
