1. ## Point line intersection

Hi All,

I need some help on this problem.

Say, in Google Earth or Virtual Earth, we define 3 pair of longitude and latitude (or x and y).
We need 3 pair because:
- The first two pair is to define the start and end, therefore, form a direct line.
- Another pair is just a point that is located somewhere else. In most of my cases (99.99%), it is located somewhere between the line (sometimes fall under the path of the line, which means I don't need any further mathematical calculation).

My question is:
How do I find the longitude and latitude intersection in that line, that is a result of the projection from the point?

2. This is one way of doing it, but it wont exactly work on Google earth though

The curve above that purple line can be calculated using radians i think. And then you'll have the distance.

3. Hi,

So far, I have been able to do the job even though I don't fully understand the mathematics behind it.
The source that I use:
Distance between a Point and a Line

That source is to calculate the distance between a point and a line. I modified it a little bit to just get the intersection point (x, y) rather than the distance.

4. Originally Posted by hwijaya
Hi,

So far, I have been able to do the job even though I don't fully understand the mathematics behind it.
The source that I use:
Distance between a Point and a Line

That source is to calculate the distance between a point and a line. I modified it a little bit to just get the intersection point (x, y) rather than the distance.