Standards /

WCPS-Manual / extendExpr

The extendExpr element extends a coverage to the bounding box indicated. The new cells are filled with the coverage's default null value. There is no restriction on the position and size of the new bounding box; in particular, it does not need to lie outside the coverage; it may intersect with the coverage; it may lie completely inside the coverage; it may not intersect the coverage at all (in which case a coverage completely filled with null values will be generated).

NOTE In this sense the extendExpr is a generalization of the trimExpr; still the trimExpr should be used whenever the application needs to be sure that a proper subsetting has to take place.

Let

C1 be a coverageExpr,
n be an integer with 0 ≤ n,
a1, ... , an be pairwise distinct axisNames with ai ∈ axisNameSet(C1) for 1 ≤ i ≤ n,
crs1, ... , crsn be pairwise distinct crsNames with crsi ∈ crsList(C1) for 1 ≤ i ≤ n,
(lo1,hi1), ... ,(lon,hin) be axisPoint pairs with loihii for 1 ≤ i ≤ n.

Then,

for any coverageExpr C2
where

C2  =  extend ( C1, { p1, ... , pn } )

with

pi is one of
pimg,i = ai(loi,hii)
pcrs,i = ai(loi,hii)crsi

C2 is defined as follows:

Note: A server may decide to restrict the CRSs available on the result, as not all CRSs may be technically ap-propriate any more.

Example

following is a syntactically valid extend expression:

extend( C, { x(-200,+200) } )