Is there a way in occ to make a union between two adjacent planar faces and get only one face?
I used "BRepAlgoAPI_Fuse" but it does not result in a single face.. it only makes a shell containing two faces..
you can merge the faces into a sewed shape and then use the ShapeTool to find the edges which are connected to only one face (ie on a boundary. )Assuming simply connected you can take these edges, and make a wire and then a planar face.
const TopoDS_Edge& E = Tool.GetCurve();
Standard_Integer neighbour = Tool.Neighbours();
// etc add edge to wire if neighbour ==1 ...