and it is measured by the angle created between those two lines.
As you can observe, far buildings appears to move slowly than the near ones.
There is a simple relationship between a star's distance and its parallax angle:
d = 1/p
The distance d is measured in parsecs and the parallax angle p is measured in arcseconds.
This simple relationship is why many astronomers prefer to measure distances in parsecs.
Limitations of Distance Measurement Using Stellar Parallax
Parallax angles of less than 0.01 arcsec are very difficult to measure from Earth because of the effects of the Earth's atmosphere. This limits Earth based telescopes to measuring the distances to stars about 1/0.01 or 100 parsecs away. Space based telescopes can get accuracy to 0.001, which has increased the number of stars whose distance could be measured with this method. However, most stars even in our own galaxy are much further away than 1000 parsecs, since the Milky Way is about 30,000 parsecs across.