Obtaining a virtual 3D model of a heart

This post will cover the subject of obtaining virtual 3D models of various hearts, to use with the 3D printer.

To start with what we have to end up with: the Connex printer which we are likely going to use needs a mesh file like VRML ore STL to print. The mesh needs to be closed, so the printer can recognize the solids which have to be printed. A mesh file is not difficult to make: every NURBS and T-spline NURBS model can be easily converted to a mesh, just as a solid made by a solid modeller.

The CT-scans of the hearts can be relatively easy converted to meshes by the LUMC experts. However, this doesn’t mean we can send this file directly to the printer. Most of the time, it is not a closed polysurface, and besides, it looks quite messy due to the low resolution of the scan and therefore the troubles to distinguish the different segments of the heart during the conversion from scan to mesh.

To get our hands on a nice and clean printable 3D model, we figured out three options:

-Cleaning a mesh model and model the missing (small) parts in it

-Buying or downloading an existing 3D model, and shape it to our needs

-Model the heart from scratch.

An overview of this options, the sub options and the (dis)advantages can be found below.Overview of CAD methods B-01

We got some experience with converting NURB models to T-spline, with various results. It seems that the succes of turning a NURBS model into an easy editable T-spline NURBS model depends strongly of how the model was build, and with how many surfaces.

We also tried editing the scan-meshes with Freeform Plus. This software gives you the possibility to edit a mesh in a clay-like enviroment, in where you can easily smear, add and deform a mesh. This method gave us our first concrete and printable result. More on this topic will be discussed in the next weblog!

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