notice: exe and output is in build file

processing_cityjson

empty data processing:

skip it, if some building is empty we skip it

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)

randomly assign, if orientation is on boundaries, we randomly assign it

avoid zero, add extreme small value to avoid variable divided by zero

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

assume it is right, since we dont need to correct incorrect data. we assume it is correct

simplify it, no adjacent values for buildigns

validation