PRETORIA GeoArt Series
Welcome to PRETORIA!
The Pretoria geocaching community is very proud to present PRETORIA, the largest GeoArt series to date in South Africa.
Aside from its rich cultural history, Pretoria is also home to an extremely active geocaching community. The Pretoria geocachers are a very social bunch and meet at least once every month to share stories, swap experiences and trackables and enjoy each other's company. During one of our get-togethers, the idea of putting our beautiful city well and truly on the geocaching map was born. It started off as a small idea but we soon realised that it would be a huge undertaking. When the call for interested parties went out, the local community responded true to spirited Pretoria form and soon all 85 caches were allocated to 21 different teams. The PRETORIA GeoArt community project commenced in January 2014 and was completed six months later in June 2014.
We hope you will enjoy exploring our beautiful city of PRETORIA.
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For English, see further on.
Daar word verstommend baie maniere gebruik om ‘n punt op die aarde te spesifiseer – die lengtegraad/breedtegraad/hoogte (LLA) waarop ‘n standaard-GPS werk is hoegenaamd nie die enigste (of selfs die beste) manier nie. Hoewel ons grootliks op LLA gestandaardiseer het is die rede hoofsaaklik histories – daar is ‘n eeuelange geskiedenis van kaarte wat in lengte- en breedtegrade gemerk is. Hierdie stelsel is egter nie sonder sy probleme nie – een waarvan cachers wat al op ver plekke gecache het bewus sal wees is dat 1 graad heeltemal verskillende afstande kan verteenwoordig, afhangend van waar jy jou bevind.
Een van hierdie alternatiewe staan bekend as ECEF: Earth-centered, Earth-fixed. ECEF is ‘n Cartesiese koördinaatstelsel, d.w.s. dit het drie loodregte asse wat by die middelpunt van die aarde sny. Enige punt op die aardoppervlak (of elders) word dan i.t.v. ‘n X-, Y- en Z-koördinaat voorgestel. Hierdie stelsel het ‘n paar groot voordele, waarvan een is dat dit navigasieberekeninge aansienlik makliker maak. Sien die volgende diagram:
Die finale posisie van die cache is:
X = 5062.493 km
Y = 2724.255 km
Z = -2756.120 km
(WGS84)
There are surprisingly many ways to specify a point on the earth. The Latitude/Longitude/Altitude (LLA) system which is used by a standard GPSr is not the only (or best) way. Although we have standardized on LLA, the reason is mainly historical - the centuries long history of maps marked with latitude and longitude. This system is however not without its problems. One with which some cachers will be familiar is the fact that 1 degree can represent quite different distances, depending on where you are!
One of these alternatives is known as ECEF: Earth-centered, Earth-fixed. ECEF is a Cartesian coordinate system - it has three perpendicular axes which intersect at the middle of the earth. Any point on the surface of the earth (or elsewhere) can then be represented in terms of an X, Y and Z coordinate. This system has a number of advantages, one of which is that it simplifies navigation calculations considerably. See the above diagram for a graphical explanation.
The final position of the cache is:
X = 5062.493 km
Y = 2724.255 km
Z = -2756.120 km
(WGS84)
