Triangulate open region of previous triangulation

I have a 3D triangulation (shown below) which is mutiple grains with a gap between them.

I want to triangulate the region between all the grains but am unsure how to do this. Is there a way this can be done?

Many Thanks

Robin

[KSSV]

YOu want to create points also in the gaps? Or just mesh them joining the sides?

[Robin Pillar]

Mesh the region inbetween all the grains

Answer 1

[KSSV]

Read about delaunayTriangulation. Take all the points (x,y) for each grain and make them a single column vector. Use deluanyTriangulation.

[Robin Pillar]

Already tried that. It just meshes everything as one object. But what I want is region between the grains meshed, not the grains themselves