The Polycystic Kidney

3D, Graphical Works, Just Learning, Retopology

Polycystic Kidney Disease is an inherited disease. Most of the time this disease is an autosomal dominant genetic trait. This results in the disease affecting at least 1 out of 1,000 Americans, sometimes even more , given that not everyone shows symptoms. The size of the affected kidney is overwhelming. This disease must be terribly painful given amount of space it intrudes on within the person’s body.

Editorial for PKD – mock ad for the PKD foundation.

To start the construction of this model, we extracted a model from DICOM data provided by the instructor. The model was exported from Mimix as an STL, improted into 3DS Max, then exported as an FBX so it could be imported into Mudbox. Once in Mudbox, I created then molded a sphere to flow with the over all shape of the kidney. A displacement map created from the high-poly kidney model and then applied to the re-shaped Mudbox sphere. This is the same process I used to create a model of my face.

Like I mentioned previously, Mudbox is AMAZING! The ease of sculpting, painting and creating detail on the model is extremely intuitive.

Screenshot of Kidney from Mudbox

The over all look and feel of the kidney changed throughout the process of building the model.  Going from Mudbox to Max to Photoshop can really take a toll on the final product.  You just have to stay calm, pay attention and keep modifying settings to get what you want.   When I was in Mudbox I spent a lot of time painting different layers, adjusting the hue and saturation of the layers, and sometimes even the opacity.  Then when you save out each file type ( the 3d geometry and the texture files) they are not always applied as you want them to be in 3Ds Max. And what I mean by that is, you have to do a lot of adjusting, the process is not as manual as you might hope. I found it easier to save the kidney from Mudbox using “Save scene to 3DS”. Then I saved each of my paint layers from Mudbox using “Save channel as Photoshop document”. This can be done  by right clicking on one of the paint layers ( you can’t right click over “Diffuse” you have to right click over one of the layers… but don’t worry it exports the entire channel ; )  ). In 3Ds max I changed the Bitmaps to link to the .psd documents. If you follow this process you have to open up the .psd in Photoshop, and turn off the red grid.

The hardest thing to get to show as I wanted was the bump layer. Turns out, you can apply it over “100”. I also had to jack up the reflection, glossiness and specular layer more than I anticipated. The grand lesson from any 3D project: no matter how quick you think you might get through to rendering, there are always more properties you can tweak. No wonder all the good projects have teams of masters working together creating this type of work.

The the final frustration -once you render out the overall image and the different channels- keeping the overall feel in Photoshop. The feel changed some after I added the specular channel and did a screen layer of the lighting channel. I started loosing the orange in some of the bubbles. However I was okay with how it changed because I am REALLY pleased with how I got some of the bubbles to show up.  I really wanted the iridescence of the cysts to come through and I think I achieved that (especially with the large bottom right cyst above the PKD logo ).

An work in progress detail I tweeted while painting the polycystic kidney

To learn more visit PDK Fountation Website.

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