Modeling Lung Anatomy
Posted by Janet on August 8, 2009
*3ds Max lung model © Denoyer-Geppert, images used with permission.
Following “Visualizing Lung Anatomy,” I can now begin to model the lung. First, I took screen shots of the lung in VolView in three orthographic views–top, left, and front. Then I set up three orthographic planes and added each image as materials to the planes. I prefer this method over using a background image because this allows you to see the images in perspective views as you rotate objects. You also don’t have to worry about shifting your objects and locking zoom, which in my version of 3ds Max gets a little quirky.
Next, I put more planes in the scene, took a screen shot of every twentieth slice from the data set, and applied the screen shots to the planes as materials. Now that I have slices of the lung from front to back, I outlined each slice in the front viewport. Notice that the outlines are all located on the same plane. This will be fixed later. (If you are wondering why the “right” lung is on the left side, it’s because the “person” is facing us so their right is our left.)
Once the outlines are complete, I calculated the distance I must offset each line in order for it to fit the profiles correctly. After the outlines are moved to their correct positions, you can clearly see the shape of a lung in the perspective view. The lines must be linked together in order for a surface to be created. I selected one outline and used the “Attach Multiple” option under the modify panel. For now, I keep the front and back halves separate so I can easily hide the back side when necessary. Then, using the “Connect” and “Refine” features under the modify panel, I connected vertices between the outlines.
Here is what the model looks like with connections between the outlines:
Using the “Surface” modifier, I created a surface using this mesh. At this point it’s not perfect. I must go back and adjust the mesh until the entire surface can be covered:
A model of the lung without holes in the model:
The lung is looking nearly perfect, but overall still appears rough. Adding “Relax” and “TurboSmooth” modifiers will help refine the mesh:
This is one way to make a model of the human lung. I chose this method because I wanted to capture the accuracy in shape and had tools to visualize CT scan data. I also chose not to model the lobes separately because they are not the primary concern for this project and can be added later using materials.