[DEVELOPMENT] Consider using a KNN to construct the intial graph

[quantumjot]

We should consider using a KNN to construct the intial graph, and compare this with the current triangulation method.

https://pytorch-geometric.readthedocs.io/en/latest/generated/torch_geometric.nn.pool.knn_graph.html#torch_geometric.nn.pool.knn_graph

This would have the additional benefit of allowing alternative hypotheses (such as crossing) for object connections in the optimisation step, at the cost of additional computational complexity.