processing CityJSON calculate the volume, area, rough index and so on processed file use cjio to convert them into correct format, so no need to worry lod/format issues
return alternative data, if some data such as triangules after cdt is not exist, we return ring instead for surface orientation judgement(there is one case,where the ring exists but the triangules is not exist because two points overlab together so there is a silver)
omit it, some cases cgal help us handle it and just return null value/throw error(what ever, the program not crash), so we just skip it and return zero value for bad data
except orientation, all index is the same as true value tested on cube three dimension is all 1
orientation is check by check the direction using google map:
the best sample may be bk building