An individual's zodiac sign and element is complemented by their ascendant sign. By the way, Chinese astrology does not use the star constellation on the eastern horizon at the time of someone's birth to calculate the ascendant. Instead, each zodiac animal sign rules about 2 hours of each day.
For example, the Rat rules from 11 pm to 1 am - so in the case of a midnight birth, the individual would have a Rat ascendant sign, whose characteristics determine their personality type. If you don't know your time of birth, check out the ascendant calculation table to see which animal best represents your character.
1-3 am: Ox
3-5 am: Tiger
5-7 am: Rabbit/Cat
7-9 am: Dragon
9-11 am: Snake
11-13 am: Horse
13-15 am: Sheep/Goat
15-17 am: Monkey
17-19 am: Rooster
19-21 am: Dog
21-23 am: Pig
23-1 am: Rat