Error converting value string to 3d point


Hi Everyone,

public Dictionary<TS3D.Point, Chamfer> ContourPointsAndChamfer { get; set; } = new Dictionary<TS3D.Point, Chamfer>(); 

i have saved without any problem some 3d objects data to Json file but when i want to get back values, i got an error to reading 3d Point in Dictionary, if i save directly point there’s no restriction to create type converter while reading the file, reader read the point and create object in the model.
i really appreciate if some one can help me on this, how to create and where need to implement Type Converter ?? (Type converter is suggested in error message string to Point)

thanks very much,
Kind Regards.