Sabyasachi is right, it's a Giant Wood Spider Nephila pilipes female (the males are tiny, barely about half a cm long). These spiders build gigantic webs, commonly reaching 2m in diameter. If you watch them for a while, you will notice an interesting behaviour- if any non-prey object (such as a falling leaf) gets caught in the web, the spider removes that part of the web and rebuilds it. You can find the males near the periphery of the web.
Do you have any dorsal shots? I have noticed that specimens of this species in the south have more white on the body than yellow (?)
TFS