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#!N  #!Rpkse The Pick Structure #!N #!EC #!N #!N Picking is 
the selection of a location on an object in an image 
by use of the mouse. A straight line from the camera 
through the location selected constitutes a "poke," which may intersect the 
object in the image in one or more places or in 
none at all. The intersections are called "picks." For example, a 
poke through a spherical isosurface results in two picks: one on 
the "front" surface and one on the "back." Picks differ from 
probes in that probes may be present anywhere in 3-dimensional space, 
picks only on the surface of an object. #!N #!N The 
pick structure is a Field, and the picked points are listed 
in its "positions" component. A number of routines in Data Explorer 
allow you to query the pick structure output by the Pick 
tool and to traverse a picked Object. (See  #!Lpies,dxall1123 h Pick-Assistance Routines  #!EL  for details.) 
The structure includes information on how to traverse the picked Object 
to reach the picked element. It also identifies: #!N #!I0 #!N 
 #!F-adobe-times-medium-r-normal--18*   #!N #!N #!I30 #!N o the connection in which the 
picked point resides (the element ID) #!N #!I30 #!N o the 
vertex of the picked element closest to the picked point (the 
vertex ID) #!N #!I30 #!N o the position of the picked 
point itself. #!N #!I0 #!N #!EF #!N #!N #!N If the 
picked Object has no connections, the element ID and the vertex 
ID both refer to the position closest to the picked point. 
Other information can be accessed with pick-assistance routines. Note: For a 
module that uses the pick structure, the Object displayed in the 
image being picked must (1) be the same as the Object 
passed to the module or (2) have a matching Object hierarchy. 
The reason for this requirement is that the output of the 
Pick tool describes the location of the picked Object as it 
exists in the hierarchy of the rendered Object. To use the 
pick structure, therefore, requires an Object with a matching structure. #!N 
#!N #!N  #!F-adobe-times-medium-i-normal--18*   Next Topic #!EF #!N #!N  #!Lshowp,dxall1041 h ShowPick Module Example--Using Color to Show a Picked Object  #!EL  #!N  #!F-adobe-times-medium-i-normal--18*   
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