TOMS661 is a FORTRAN77 library which interpolates scattered 3D data, also known as "qshep3d", by Robert Renka.
TOMS661 takes a set of data values WDAT(XDAT,YDAT,ZDAT), where the points (XDAT,YDAT,ZDAT) are "scattered" in 3D, and constructs an interpolating function W(X,Y,Z) which matches the given data and extends smoothly through 3D space.
TOMS661 is ACM Transactions on Mathematical Software Algorithm number 661. The original text of any ACM TOMS algorithm is available through ACM: http://www.acm.org/pubs/calgo or NETLIB: http://www.netlib.org/toms/index.html
TOMS661 is available in a FORTRAN77 version and a FORTRAN90 version.
RBF_INTERP_ND, a FORTRAN77 library which defines and evaluates radial basis interpolants to multidimensional data.
TOMS660, a FORTRAN77 library which takes scattered 2D data and produces an interpolating function F(X,Y).
You can go up one level to the FORTRAN77 source codes.