#!F-adobe-helvetica-medium-r-normal--18*
#!N 
#!CDarkGreen 
#!N  #!Rprojmet Changing the Projection Method #!N #!EC #!N #!N Data 
Explorer provides two methods of image projection. These methods make it 
possible to map a three-dimensional image onto a 2-dimensional screen. The 
two methods are: #!N #!I0 #!N #!N #!I0 #!N  #!F-adobe-times-bold-r-normal--18*   Perspective 
#!EF #!I50 #!N Perspective projection simulates normal camera and human visual 
systems, thereby providing realistic rendering of objects. While it is realistic, 
it does not preserve the exact shape and measurements of the 
object, and parallel lines usually do not project as being parallel. 
#!N #!I0 #!N  #!F-adobe-times-bold-r-normal--18*   Orthographic #!EF #!I50 #!N Orthographic projection provides 
a less realistic view of an object than perspective projection. However, 
orthographic projection does preserve exact scale measurements and parallel lines. One 
way to think about orthographic projection is that it is as 
if the distance between the front and back of an object 
is small, relative to the distance between the object and the 
camera. Orthographic is the default projection method. It is quicker to 
render an object in orthographic projection than in perspective. #!I0 #!N 
#!N #!N #!N The differences between these two methods become evident 
when using the view controls in certain modes. For example, the 
 #!F-adobe-times-bold-r-normal--18*   Zoom #!EF mode behavior depends on the projection method, as 
does the behavior of the 3-D cursor (  #!F-adobe-times-bold-r-normal--18*   Roam #!EF 
and  #!F-adobe-times-bold-r-normal--18*   Cursors #!EF modes). The differences are discussed in the 
sections that discuss these modes. For more information about these projection 
methods, consult a computer graphics text. #!N #!N You can select 
the projection method by using the  #!F-adobe-times-bold-r-normal--18*   Projection #!EF option box 
on the  #!F-adobe-times-bold-r-normal--18*   View Control... #!EF dialog box. #!N #!N #!N 
 #!F-adobe-times-medium-i-normal--18*   Next Topic #!EF #!N #!N  #!Ltall304,dxall304 h Setting the View Angle  #!EL  #!N  #!F-adobe-times-medium-i-normal--18*   #!N 
