Hi Andrzej and Gerd,
for your examples
1 0
0 7
0 1
7 0
is 2 for the middlepoint mathematical correct: (h1 + h2 + h3 + h4) / 4.
My interpolation is the that:
We live in a world with "triangular" surface (like in a computergame).
We looking for a point p for the "surrounding" 4 points from the hgt. They form
a rectangle (or square).
The 4 point form 2 triangles (for me):
hlt hrt (height right top)
+---+
| /|
| / |
|/ |
+---+
hlb hrb
We looking in which triangle our point p is.
A triangle define a plane and we can use a "3-Punkt-Gleichung" (don't know the
english word).
For the left triangle:
use hlt as coordinate origin
hrt -= hlt;
hlb -= hlt;
qy -= 1;
and calculate hlt + qx * hrt - qy * hlb
For the right triangle:
use hrb as coordinate origin
hrt -= hrb;
hlb -= hrb;
qx -= 1;
and calculate hrb - qx * hlb + qy * hrt
This principle can be a little extend:
hlt hrt
+---+
|\ /|
| x |
|/ \|
+---+
hlb hrb
It's easy to calculate the middlepoint and then we have 4 triangles. Then we
have to decide, which triangle we need.
Just we have 4 triangles. (So we have our "triangular" surface.)
And so on ...
Frank
---
Diese E-Mail wurde von Avast Antivirus-Software auf Viren geprüft.
https://www.avast.com/antivirus
_______________________________________________
mkgmap-dev mailing list
mkgmap-dev@lists.mkgmap.org.uk
http://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev
