Objective Simulation of surgical cutting, tearing and cauterization in real-time
Duration 06.2013 — now
Virtual cutting of deformable objects is at the core of many applications in interactive simulation. The ability to simulate surgical cuts, dissection or soft tissue tearing is essential for augmenting the capabilities of existing or future simulation systems. In the team Mimesis, we addressed this subject in different ways, the main ideas are presented below.
We combine a new remeshing algorithm with a fast finite element approach. Using combinatorial maps a separation induced by a cut or tearing is incorporated into a volumetric mesh. Our remeshing idea is based on simple topological operations, that we will explain in two dimensions first and in three dimensions in the latter.
Our approach starts off with a discrete representation of an object as a mesh and the position where a separation is taking place (in grey). Intersections between the separation and edges of the mesh are detected (red).
The triangles around edges that have been identified as being cut, are split into three new triangles inserting a new node on the cut for each cut triangle.
The inserted nodes are connected using an operation called flip 2 to 2. We finally obtain a discrete representation of the separation inside the mesh and duplicating of the inserted nodes results in a mesh that can separate at the separation curve.
In a similar way, our method works in three dimensions: we apply a split 1-4 to put points on the separation surface, then we connect these points by edges by a flip 2-3 and in the last step we put triangles between these edges using an edge removal.
Following this procedure, we obtain a triangular approximation of the separation surface inside the tetrahedral mesh. Using the representation combinatorial maps avoids unnecessary updates of topological structures and allows a computation in real time.
However, solely working with the remeshing idea, a separation surface close to a vertex of the tetrahedral mesh may lead to numerical instabilities and an increased computational cost. Therefore we combine the remeshing idea with an approach, that moves nodes that are close to the separation surface.
The results we obtain are specifically interesting, as they maintain the real-time aspect necessary for simulating surgical interventions. More information can be found in the publication “Virtual Cutting of Deformable Objects based on Efficient Topological Operations” mentioned below.
The method has been applied in the following papers: