A Kernel System for 3D GIS Applications

tllo~~glit as t l ~ r transitional approac.Il for 3D GIs tlcvrlA ker71cl systcrrl lulvich can s~tpport .?-dime7lsio~~r~l (11)plicntio7rs of G I s is plaposed. Internnlly. s1)atiol rlr~trt arc ntc~~laged by o 2-rlimensionc~l dnta stn~ctule. sincc 7rlost of the yrc~ct'icfll G I s datcl clrr: 8-r~irrrerf,siorlr~~. 1 7 1 fnnrrntion (tbo7tt the 2-r~xis, i.e. dir.ection of Ir.ci!lht, is scpn7,atcrl frorrl coor.(li7tntc.s rlescr-ihi7~!j objects. nrttl trec~ted ns one of the (~ttribittcs nttctchetl to objects. Tltis zs jrtst the snrrle us the so calletl 2.5D rlcscripfiorr rrtlrich is r~pplierl ezterlsivrly to t1esc:r-il~ .'1'-rlirrtcrr,siorrc11 olcjccts irl GIs, cx:cept that roe cctc:rrtlet/ thf: 2 . 5 0 rlc,sc:r.i]~t'iorl to be nble to llolrl rrr~~ltiple h ight iiifor~rl(ltjo7l. Wv (:(dl tlre ezterrrled 2 . 5 0 tle.sc~*~ptiorl tl c 80-11 rlescr-iptiorr to distin/l?lisll it frorrl the tmditiorlnl 2.5D orte. Tlre 11ropose(l kf!rrlel coritains (1 set of C++ closs librct7ie.s defi:fillirlg sonlc b ~ s i c s1mtinl objects. For differrnt ctpplicntiorrs, special objects can be deri~~ed easily fmrrr the basic librnrie,~ by itsing the object-orie~lted trrlrriic. Wc slloru the effectioene.~.~ of ,9-rlirnerrs.ionnl s?tl)portir~!l ilbility of the proposer1 ke~ne l systcrri by (11)pl!ying it to irri1)le~trerd o nelu en:1)ressiori technic for u~r~~lktltro~tgh, wlllch (Edsploy objects 271 differ.crrt rletnils accorrling to tlrcii disfarlt:es frorr~ the vieur poi~lt.