Retopology

Retopology... retopologization... however you slice it, it's a difficult word to say. But immensely useful to actually do. For example, most items that have been scanned by a device have an ugly, ugly mesh. Usually very dense, and all triangles.

This is a mesh from a femur that was edited in Mimics. It is from a CT data set, taken from the skeleton that I'm currently modeling. Mimics is a program similar to OsiriX - it can take DICOM data (CT, MRI, etc) and export a file that can be read by a 3D program. This is wonderful for achieving highly accurate models, but not so good for clean meshes.















The .obj file is being viewed in a program called MeshLab. It has the ability to handle high-polygon meshes very well.















The femur that I am working with exported with around 139,000 faces. This actually isn't that bad, comparatively speaking. I've easily come across a 4 million poly export from a DICOM program. Even so, this mesh would be a pain to texture and animate with.

This is Zbrush. My main love for Zbrush (and it's a recent discovery) is the retopology tool.















By drawing new polygons on the surface of your high res model, you can export a low res stand-in. The model that I generated has 3,200 polygons. A far cry from 139,000.















I could have made it with fewer polygons, but I found that the mesh reacted best to a slightly denser layout. Perhaps because I'm new to this whole retopology endeavor and haven't learned all the tricks yet. I do have an entire skeleton to work on, so hopefully I'll continue to learn.

The wire frame is now as clean as you make it, allowing for potentially great edgeflow. This makes texturing and animating much, much simpler.


















However, this is not what I find the most useful attribute of retopologization. Zbrush allows you to project your original high res mesh back onto the low res model. By matching how many times you up the density during retopologization, subdiving the low res obj that many times again, and then importing the high res mesh on top of this highest division, it becomes a smooth stepping process between the lowest and highest resolutions.















Did that sound complicated? It was very fun for me to figure out, let me tell you. If it didn't... well, you are smarter than I am. Kudos.
















In any case, there are tutorials out there on the retopology tool. If you are interested in my entire workflow from Mimics/OsiriX to Zbrush, let me know.

















These images that you see are screen shots of the femur as exported from Mimics. I have not done any further editing to it yet. I plan to do so, of course. I will post more images as my bones are completed.

Mudbox Tutorials

Mudbox Tutorials:
Wayne Robson (i.e. DarthWayne)

Wayne has been working in both Zbrush and now Mudbox for a very long time. His tutorials are online and free, and utterly fantastic. I really cannot teach Mudbox nearly to the level that he can, so head over to these sites to check them out. The two 'series' are meant to work in conjunction with one another.

Mudbox "From the Ground Up" series:









Mudbox "Quickstart" series:

Example: "This is a real time viewport capture of my latest work inprogress 'Insectoid'. He only stands at 4 million polys so far."

OsiriX Tutorial

Okay, as I was finishing up an assignment in OsiriX, I discovered this nifty shading control. So, as I went through it, I decided that others needed to know about this. In my own little world, no one else knew about this, so I wrote a tutorial. So, here comes OsiriX tutorial the second.

OsiriX: The Shading Menu

This covers, as it states, the shading menu within OsiriX. It is a set of very 3D-esque controls that influence the ambient, diffuse, and specular settings of your data set. Basically, it allows you to give your renders just a little bit more polish.