Line 'Z' value from a point at zero elevation

[Steven P]

Sunday night so my brain is asleep and I can't remember how I did this....

 

Given a point with 0 elevation how do I get the point including elevation of a line above it.

 

For example, my point: ( 5 5 0 ) is under the line (2 5 10) (8 5 20), I want the value between 10 and 20 corresponding (here it should be 15)

 

And I can't remember how!

Thanks for any tips

 

 

[BIGAL]

Its a ratio thing,

(dist1 / tot dist) so get horizontal distance between end points and the distance from say start point to point, in XY plane.

height of end points

So ((Ht1 - Ht2) * dist ratio) +  ht1. 

 

Check with calculator. 

 

[Steven P]

Thanks, will do it that way. I was thinking I'd seen a VLA- something somewhere, maybe not - your idea will work.