dx-doc 1:4.4.4-7 / usr / share / doc / dx / help / dxall1120

#!F-adobe-helvetica-medium-r-normal--18*
#!N 
#!CNavyBlue #!N  #!Rgns Growing and Shrinking Partitioned 
Data #!N #!EC #!N #!N The routines listed at the end 
of this section are necessary for processing Composite Fields. #!N #!N 
Some modules (e.g., filters) require information from the neighborhood of each 
point. Since partitioning divides data into spatially disjoint subsets for independent 
processing, a neighborhood may be divided among different partitions: for example, 
a filter kernel may overlap the boundary between two partitions. In 
such cases, processing one partition requires information that resides in the 
other. #!N #!N In order to facilitate such information sharing, Data 
Explorer includes routines that support temporarily overlapping partitions.  #!F-adobe-times-bold-r-normal--18*   DXGrow() #!EF 
modifies its input Field and adds to each partition information from 
the partition's neighbor(s). #!N #!N Because  #!F-adobe-times-bold-r-normal--18*   DXGrow() #!EF modifies its 
input, the calling routine must use  #!F-adobe-times-bold-r-normal--18*   DXCopy() #!EF to copy 
the input structure if that structure is not to be modified. 
After this boundary information has been accrued, the processing of the 
partition may be handled independently since all information required to produce 
correct results for the original partition is available in it. For 
example, in the case of filtering, boundary information is added so 
that wherever a filter kernel is placed in the original partition, 
the kernel does not extend outside the grown partition, producing correct 
results in the original partition. After processing the Field produced by 
 #!F-adobe-times-bold-r-normal--18*   DXGrow() #!EF ,  #!F-adobe-times-bold-r-normal--18*   DXShrink() #!EF must be called to 
shrink any components that have not been shrunk by the caller, 
and to remove extra references to the original components that were 
put in the Field by  #!F-adobe-times-bold-r-normal--18*   DXGrow() #!EF . #!N #!N 
When  #!F-adobe-times-bold-r-normal--18*   DXGrow() #!EF is called, the depth of an overlap 
region is specified by specifying the number of  #!F-adobe-times-medium-i-normal--18*   rings #!EF 
to be accrued. An element is said to be in the 
 #!F-adobe-times-medium-i-normal--18*   k #!EF th ring if it has at least one 
vertex in the  #!F-adobe-times-medium-i-normal--18*   k #!EF th ring. A vertex is 
in the 0th ring if it exists both in the partition 
and the neighbor, and is in the  #!F-adobe-times-medium-i-normal--18*   k #!EF th 
ring if it is not in a lower ring and an 
element in ring  #!F-adobe-times-medium-i-normal--18*   k-1 #!EF is incident upon it. Most 
frequently, such modules produce results for each vertex on the basis 
of the elements incident on that vertex; this is achieved by 
requesting that  #!F-adobe-times-bold-r-normal--18*   DXGrow() #!EF include 1 ring: those elements from 
neighboring partitions that are incident on vertices that exist in both 
partitions. #!N The treatment of the exterior boundary of regular grid 
data is specified by a parameter to  #!F-adobe-times-bold-r-normal--18*   DXGrow() #!EF . 
You may specify that the Field not be expanded beyond its 
boundary (i.e., that the exterior partitions not be expanded except on 
the sides that border other partitions). Alternatively you may specify that 
the Field be expanded beyond its original boundaries, with the new 
data being filled in one of three ways: with a constant 
value; with the replicated value from the nearest edge point in 
the original Field; or with nothing, only reserving space for the 
new data but leaving its contents undefined. #!N #!N While it 
is necessary that the footprint of a filter kernel, placed anywhere 
in the original partition, not extend past the grown partition boundary, 
it is probably not necessary to apply the filter in the 
boundary regions accrued from neighbors; these regions are properly handled during 
the processing of the neighboring partition. Data Explorer also includes routines 
that query the original number of positions and connections (in the 
case of irregular grids) or the offset relative to the grown 
partition and size of the original partition. #!N #!N Frequently, modules 
do not require all components of a Field that are dependent 
on the positions to be grown. To avoid accruing information that 
will not be required during processing,  #!F-adobe-times-bold-r-normal--18*   DXGrow() #!EF requires the 
calling application to specify which components, in addition to positions and 
connections, will be required. #!N #!N Modules using  #!F-adobe-times-bold-r-normal--18*   DXGrow() #!EF 
have the option of producing results corresponding to the positions of 
the larger grown Field or, more efficiently, producing results corresponding only 
to positions of the original smaller Field. Even though the former 
method is less efficient, involving more data movement and perhaps more 
calculation, it is sometimes more convenient. Therefore, the  #!F-adobe-times-bold-r-normal--18*   DXShrink() #!EF 
function is provided to shrink all components that depend on or 
reference positions or connections back to their original size. If the 
user has already shrunk the positions,  #!F-adobe-times-bold-r-normal--18*   DXShrink() #!EF will leave 
them unmodified. In any case, the  #!F-adobe-times-bold-r-normal--18*   DXShrink() #!EF function must 
be called after operating on a grown Field in order to 
remove references to the "original" components that were placed in the 
Field by  #!F-adobe-times-bold-r-normal--18*   DXGrow() #!EF for later use by  #!F-adobe-times-bold-r-normal--18*   DXShrink() 
#!EF . #!N #!N For each component specified in the component 
list passed to  #!F-adobe-times-bold-r-normal--18*   DXGrow() #!EF , a component named "original 
 #!F-adobe-times-medium-i-normal--18*   componentname #!EF " is created.  #!F-adobe-times-bold-r-normal--18*   DXShrink() #!EF will rename 
each of these to its original name. Therefore, for components you 
have modified (e.g., data), you should remove the corresponding original component 
("original data" in this example) before calling  #!F-adobe-times-bold-r-normal--18*   DXShrink() #!EF . 
#!N Both  #!F-adobe-times-bold-r-normal--18*   DXGrow() #!EF and  #!F-adobe-times-bold-r-normal--18*   DXShrink() #!EF operate in 
parallel on Composite Fields. For that reason,  #!F-adobe-times-bold-r-normal--18*   DXGrow() #!EF must 
be called prior to any subtasking invoked explicitly by the calling 
application;  #!F-adobe-times-bold-r-normal--18*   DXShrink() #!EF must be called after any such subtasking 
has been completed. #!CForestGreen #!N #!N  #!F-adobe-courier-bold-r-normal--18*   #!N #define GROW_NONE NULL 
#!N #define GROW_REPLICATE ((Pointer)1) #!N #define GROW_NOFILL ((Pointer)2) #!EF #!N #!N 
#!EC #!N #!I0 #!N #!N #!I0 #!N  #!F-adobe-times-bold-r-normal--18*    #!F-adobe-times-bold-r-normal--18*   Object DXGrow() 
#!EF #!N Object DXGrowV(); #!EF #!I50 #!N Add information from neighboring 
partitions to a Composite Field. See  #!Ldxgrov,dxall1273 h DXGrow, DXGrowV  #!EL  . #!N #!I0 #!N 
 #!F-adobe-times-bold-r-normal--18*    #!F-adobe-times-bold-r-normal--18*   Field DXQueryOriginalSizes() #!EF #!N Field DXQueryOriginalMeshExtents(); #!EF #!I50 #!N 
Return information about the size of the original Field used as 
the input to  #!F-adobe-times-bold-r-normal--18*   DXGrow() #!EF . See  #!Ldxqosm,dxall1346 h DXQueryOriginalSizes, DXQueryOriginalMeshExtents  #!EL  . #!N 
#!I0 #!N  #!F-adobe-times-bold-r-normal--18*    #!F-adobe-times-bold-r-normal--18*   Object DXShrink() #!EF #!EF #!I50 #!N Removes 
information added to an Object by  #!F-adobe-times-bold-r-normal--18*   DXGrow() #!EF . See 
 #!Ldxsk,dxall1395 h DXShrink  #!EL  . #!I0 #!N #!N #!N #!N #!N  #!F-adobe-times-medium-i-normal--18*   Next Topic 
#!EF #!N #!N  #!Lhash,dxall1121 h Hashing  #!EL  #!N  #!F-adobe-times-medium-i-normal--18*   #!N