Ah, yes, I can see it now. This is Delias pasithoe which I mentioned sometimes can be seen in my garden while we were watching the Troides circling around the trees covered with flowering Bauhinia vines.
Someone must have planted Lantana at the viewpoint, there never used to be any there, althought there is lots of Lantana along the road on the town side of the mountain. The village visible in the photo is not Chiang Mai (for those who do not know how huge Chiang Mai city is), but is the Maew (Hmong) hilltribe "village" on the western side of the mountain. This is really a tourist trap souvenir shop village, rather than an authentic hilltribe habitation.
I should add that this viewpoint (altitude 1,530 m) has a cliff immediately next to it with forest below, and back in the 1980s this was one of the main study points for Sphingidae on this mountain, which formed part of the research behind the 2nd volume of Moths of Thailand.