#!F-adobe-helvetica-medium-r-normal--18*
#!N 
#!N  #!Rinval Invalid Positions and 
Invalid Connections Components #!N #!N #!N The "invalid positions" and "invalid 
connections" components allow positions or connections to be marked as not 
having valid data. This is useful, for example, for observational data 
defined on a regular grid but with occasional missing observations, or 
for simulation data defined on a regular grid but with a 
"hole" covered by another grid, perhaps at a higher resolution. The 
"invalid positions" component can be an Array of bytes or unsigned 
bytes, one for each position, where the component is dependent on 
positions (i.e., has a "dep" attribute of "positions."). In that case, 
the value 1 indicates that the corresponding position is invalid, and 
0 that the corresponding position is valid. Alternatively, the "invalid positions" 
component can be an Array of signed or unsigned integers, where 
the component references the positions (i.e., has a "ref" attribute of 
"positions"). In that case, the component contains a list of the 
indices of the invalid positions. The first method is more space-conserving 
when there are a large number of invalid elements; the second, 
when there are a relatively small number. See  #!Lcompute,dxall795 h Compute  #!EL  in IBM 
Visualization Data Explorer User's Reference for a way to convert from 
the "ref" type to the "dep" type. #!N #!N The "invalid 
connections," "invalid faces," and "invalid polylines" components can be defined in 
an analogous way. #!N #!N #!N  #!F-adobe-times-medium-i-normal--18*   Next Topic #!EF #!N 
#!N  #!Ltall213,dxall213 h Tangents, Normals, and Binormals Components  #!EL  #!N  #!F-adobe-times-medium-i-normal--18*   #!N 
