I am currently trying to figure out the insane marching cube algorithm (a.k.a. "3D contouring" or "Surface reconstruction"). According to Paul Bourke,
The position that it [the isosurface] cuts the edge will be linearly interpolated, the ratio of the length between the two vertices will be the same as the ratio of the isosurface value to the values at the vertices of the grid cell.
I can't seem to wrap my head around this statement. Does he mean something like: $\frac{L_1}{L_2}=\frac{I}{I_1+I_2}$
Where $L_1$ is the distance between the cut and vertex 1, $L_2$ is the distance between the cut and vertex 2, $I$ is the isosurface level, $I_1$ is the isosurface value of vertex 1, and $I_2$ is the isosurface value of vertex 2.
Is this equation correct?