Revealed

A blog about scientific and medical visualization and all that’s involved.

Posts Tagged ‘VolView’

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.

LungModel1

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.)

LungModel2LungModel3LungModel4

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.

LungModel5

Here is what the model looks like with connections between the outlines:

LungModel6

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:

LungModel7

A model of the lung without holes in the model:

LungModel8

The lung is looking nearly perfect, but overall still appears rough. Adding “Relax” and “TurboSmooth” modifiers will help refine the mesh:

LungModel9

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.

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Posted in anatomy, digital 2D/3D, my projects, techniques | Tagged: , , , , | 2 Comments »

Visualizing Lung Anatomy

Posted by Janet on July 27, 2009

One of the projects I’m currently working on at home involves building a 3D model of the right lung. To make sure the model will be as accurate as possible in terms of shape, I would need to know the lung anatomy before I begin building the model.

The first thing I did was going to a library to look at drawings and photographs of lungs. I did a few quick sketches and wrote down some notes on how I will approach this in a 3D program:

sketch1sketch2
Now comes the fun part…

Next, I went to CVS and bought some Crayola modeling clay and began to build a small lung model while looking at online images of the lung. I tried to find as many variations in as many angles as possible, but most resources only showed the standard views. The e-anatomy website very helpful for this initial step, since it provides cross sectional images, labels of structures, and several different ways of presenting the structures. (The website is free, but registration is required to gain full access to the labels and features. High res images and full screen mode are available with a fee, but for our purpose this isn’t necessary.)

The purpose of making a clay model is to get a concrete physical sense of the three-dimensional shape. I find this step very important because it forces you to piece together two-dimensional visuals into a three-dimensional object. It is through this process that I begin to realize the complexity of the shape of a lung.

Below: Clay lung, heart, and a piece of unused clay.

clay-lung

To begin the digital visualization process, I looked further to find visualization tools that would allow me to use actual human data, look at the structures from various angles, and isolate unnecessary structures. Osirix, an open source DICOM viewer, is perfect for the job. It even has data sets available for download. The only problem is…Osirix is Macs only, and I only have access to PCs.

After poking around for a while, I found a similar product called VolView that works on a PC. VolView comes with a $1000 yearly or a $2500 unlimited licencing fee, but it has a 30 day free trial for download. I was able to import a data set from the Osirix website into VolView. My impression of VolView after two days is that it is very easy to navigate, comes with instructions (Help –> Help Topics), gives good results, and has powerful features. One thing I haven’t figured out is whether there is a cut feather that allows the user to trim away unnecessary parts. There seems to be a segmentation tool under the “Analysis” tab, but the instructions for this feature is limited and it is a feature that does not allow “undo.” That is scary. The first time I tried it, it messed up a model I had been playing with for two hours, but it warns you first so you feel like it’s your own fault for not listening. Luckily I was able to reproduce the same result ten minutes later. Here is a screen shot of my lung visualization:

volview-lung
…and a detailed shot of the lung. You can see the bronchi entering the right lung, but notice there are still some artifacts on the side.
volview-lung-detail

*See “Modeling Lung Anatomy” for the next step in this process.

Posted in anatomy, digital 2D/3D, my projects, photography/imaging, techniques | Tagged: , , , , | 4 Comments »