asylum (DayZ)

You really can't just load everything on map at load time. If you did, you would really see an fps drop or the map may not load at all and lock your game. Every item ( building, vehicle, weapon, grass billboards, tree etc) all require draw calls ( google it). Thus you use an lod ( level of detail, which is usually distance based from the camera with clipping planes etc. ) system and also a camera culling frustrum to prevent things from unnessasarily loading into the world that are not being seen by the player ( what would be the point of loading everything you can not see? It would just require more resources) and yes sometimes this causes object poping that sometimes the player may notice. All of these objects and their materials get loaded into the ram of your video card. So you can imagine that if everything was loaded into ram it would kill your card, things like textures that may be 512x512 you would think would take up little space because you see an image file as say 150kb, the reality is that this is a compressed image, when this texture is loaded into ram it has to be decompressed therefore requiring a lot more space. You can group object in some game engines that will only pull one draw call instead of many, just like multiple objects may share the same texturespace in one file for their uv mapping. Creating games take a lot of creativity and thought. Anyway regardless of the lesson above ( which is very primative ), trying to load this entire world, which is huge would be a game breaker. There is a lot that goes into developing a game and the technology used to create that game. Happy gaming and enjoy the ride. Asylum