Is it safe to take off from mall rooftop and fly below the rooftop level?
And I see the limit is 500m. Will the height counted from ground level or rooftop level?

Thanks

Anyway sometime dji forum cant be accessed it said ip outside of range, but it's just my data, works fine on my wifi

It should not be an issue.

max height starts counting from startlevel, so rooftop....

Hello, the limitation of the altitude is depends on the level where it takes off.