
niluvu dayta

bhougolika saastramlo, surveying, hydrography mariyu navigation, niluvu daytum ledhaa altimetric daytum, anedi bhoomi-kattubadi unna lakshanaala (bhuubhaagam, snaanapu kolata, neeti sthaayi mariyu nirmita nirmaanaalu) mariyu upagraha kakshyala ettulu mariyu vimanayanamlo niluvu sthaanaala kosam upayoginche suuchana samanvaya uparitalam.
grahala saastramlo, niluvu datumlanu sunna-etthu uparitalam ledhaa sunna-sthaayi suuchana anie kooda pilustaaru.
niluvu daytum kosam saadhaaranamgaa sweekarinchina pramaanaalalo eee krindi vidhanalu unnaih 
nipunulu upayogistunna pramukha niluvu datumlalo 1929 naati jaateeya geodetic niluvu daytum mariyu 1988 naati uttara america niluvu daytum unnaayi.
paddhatulu.
saadhaaranamgaa, samudra mattaniki ettulo ettulanu tarachugaa udaharistaaru, ayithe "samudra mattam" antey modata anukunna daanikante chaalaa sanklishtamaina samasyah edainaa oka pradaesam mariyu samayamlo samudra uparitalam yokka etthu anedi alalu, gaali mariyu pravahalu, vaataavarana peedanam, alalu, sthalaakruthi mariyu parvataalu undatam valla gurutvakarshana balamlo thedaalu vanti aneka prabhaavaala phalitamgaa untundi.
bhoomipai vastuvula ettunu kolavadaniki, upayoginche saadhaarana daytum sagatu samudra mattam (msl). idhi oka nirdishta 19 samvatsaraala chakramlo teesukunna ganta neeti etthu yokka ankaganita sagatuga varninchabadina oka alala dattaamsam. eee nirvachanam sagatuna alala garishtalu mariyu alpaalu (suuryudu mariyu chandruni gurutvakarshana prabhaavaala valla sambhavistundi) mariyu swalpakaalika vaividhyaalanu anchanaa vestundi. idhi sthaanika gurutvakarshana balam yokka prabhavalanu tolaginchadu, anduvalla geodetic datumku sambandhinchi msl yokka etthu prapanchavyaaptamgaa mariyu oka desham chuttoo kooda maarutundi. aaa desamloni anni mapping mariyu surveying kosam praamaanika "samudra mattam" gaa upayoginchadaaniki oka nirdishta binduvu vadda sagatu samudra mattanni deshaalu enchukuntaayi. (udaaharanaku, grate britainlo, jaateeya niluvu daytum, ordinance daytum nyoon, 1915 mariyu 1921 madhya kaarnvaalloni nyoon vadda samudra mattam yokka sagatu aadhaaramgaa untundi). ayithe, oka desham nirvachinchina sunna etthu maroka desham nirvachinchina sunna ettutoe samanam kaadu (endukante msl pratichota okela undadu), anduke sthaanikamgaa nirvachinchina niluvu datumlu okadaanikokati bhinnamgaa untaayi.
natical chaartla kosam datumnu enchukunetappudu vaerae suutram upayoginchabadutundi. bhadrata kaaranaala drishtya, oka navikudu yea samayamloonainaa sambhavinche kaneesa neeti lothunu telusukogalagaali. eee kaaranamgaa, natical chaartlooni lotulu mariyu alalu chaart datumku sambandhinchi kolustaaru, idhi alalu arudugaa padee sthaayi kante diguvana nirvachinchabadindi. idhi sarigga elaa enchukobadutundanedi chaartulo unna praantamlooni alala paalanapai mariyu prasnaarthakam chartunu utpatti chese hydrographic karyalayam yokka vidhaanampai aadharapadi untundi; oka saadhaarana nirvachanam atyalpa khagola alalu (gurutvakarshana prabhaavaala nundi oohinchadagina atyalpa alalu), ledhaa takkuva takkuva neeru (prati roeju sagatu atyalpa alalu), ayithe konnisaarlu chaalaa takkuva alala shrenulu unna neetilo emm. ess. ell. nuu upayogistaaru.
dheeniki viruddhamgaa, oka ooda takkuva vantena ledhaa ovar head power cable kinda surakshitamgaa vellaalante, naavikuniki maast head mariyu addanki madhya kaneesa clearance telusukovali, idhi adhika aatupotla samayamlo sambhavistundi. tatphalitamgaa, vantena clearancelu modalainavi. atyadhika khagola alalu ledhaa sagatu adhika neeti buggalu vanti adhika alala aadhaaramgaa datenku sambandhinchi ivvabadataayi.
bhoogarbha shaastram antataa samudra mattam sthiramgaa undadu, kabatti chaalaa deerghakaalika prakriyalanu adhyayanam chesetappudu alala datumlu takkuva upayogapadataayi. konni sandarbhaallo samudra mattam assalu vartinchadu-udaaharanaku maars uparitalaanni mapping cheyadaaniki-sagatu vyaasaartham vanti vaerae "sunna etthu" nii upayoginchamani balavantam chestundi.
geodetic niluvu daytum kontha nirdishta sunna binduvunu teesukuntundi mariyu samudra mattalaku marinta suuchana lekunda, upayoginchabadutunna geodetic namuunaa aadhaaramgaa ettulanu lekkistundi. saadhaaranamgaa, prarambha suuchana sthaanam oka tide gaze, kabatti aaa samayamlo geodetic mariyu tidal datumlu saripolavachu, conny samudra mattam vaividhyaala kaaranamgaa, rendu pramaanaalu marekkada saripolakapovacchu. gurutvakarshana aadhaarita geodetic datumku oka udaaharana navd88, idhi uttara americalo upayoginchabadutundi, idhi kenadaaloni cubecloni oka binduvunu suuchistumdi. doublugs 84, grs80 ledhaa nad83 vanti deerghavruttaakaara-aadhaarita datumlu geoidku gananeeyamgaa bhinnamgaa unde saiddhaantika uparitalaanni upayogistaayi.
rakalu.
niluvu datumla yokka saadhaarana rakaalu
akshaamsam mariyu rekhaamsamto paatu, etthu oka sthaanaaniki trimiteeya "geodetic coordinatelu" ledhaa "bhougolika coordinatelanu" andistundi.
bhoomipai, lopala ledhaa paina sthalaakruthi lakshanam yokka sthaanaanni puurtigaa paerkonadaaniki, bhoomi yokka kendram ledhaa uparitalam nundi niluvu dooraanni kooda paerkonaali. bhoomi oka golam kaadu, conny oka dvi-akshakara deerghavruttaakaaraanni anchanaa vese kramarahita aakaram. idhi daadaapu golakaramlo untundi, conny bhoomadhyarekha vadda vyaasaartham dhruwala dwara koliche vyaasaartham kante 0.3 saatam peddadigaa chese bhoomadhyarekha ubbu kaligi untundi. chinna aksham sumaruga bhramana akshamtho samanamga untundi. prarambha naavikulu samudraanni niluvu datumga upayoginchagala kshitija samaantara uparitalamgaa bhaavinchinappatikii, vaastavaaniki idhi alaa kaadu. bhoomi daani gurutvakarshana kshetramlo samaana sambhaavya shakti porala shrenini kaligi undhi. etthu anedi eee uparitalaaniki samakonamlo, sumaruga bhoomi yokka kendram vaipu kolata, conny sthaanika vaividhyaalu samaana poralanu kramarahitamgaa chestaayi (ayithe sumaruga deerghavruttaakaaramlo). ettunu nirvachinchadaaniki yea poranu upayoginchaalo enchukovadam ekapakshamgaa untundi.

