About the image

There are many rendered portraits in a lot of galleries. I was always impressed by the high quality of the MentalRay FastSkin shader and how easy it was to set it up once you understood the basic concept of how skin works. But as I ‘only’ have Cinema 4D, MentalRay is not an option for me. But isn’t it possible to render realistic skin in Cinema 4D? I wanted to find out with this project.

Modeling

I usually start my 3d models with a simple cube (box modeling). I know that many prefer point-by-point modeling (or poly-by-poly) but I like using a cube and ‘cutting’ the detail in, step-by-step. Box modeling allows me to quickly block out the basic shape of the figure and thus to have a better feeling for the proportions of the model. But because I am using good references, any modeling technique would have worked.

The face finished, I began laying out the UVs (maybe the most annoying part of this job). Fortunately I found UVLayout (by Headus), a program that flattens 3D geometry automatically.

Textures

I took the model into ZBrush to add a texture to the face. Every inch of the texture comes from high-resolution photos which where projected onto the model with the ZBrush tools. Wesclei Barbosa has written a tutorial about how to do that. All my reference photos as well as the texture references are from www.3d.sk

This is how the final head texture looks:

I used this same texture to create the skin details. I turned it into a black & white image and created a mask of it in ZBrush. Now I was able to use the Inflate brush and sculpt all the little skin details. This technique is explained in this video tutorial. I also included some volume for the hair with a custom brush. Finally I created and extracted a displacement map of the head.

The skin shader

Now comes the hardest part: setting up the skin shader. For this image I used the Vreel Skin Shader, a plug-in shader for Cinema 4D that allows you to set up different layers of skin and which also includes a SSS effect. It is possible to setup parameters for secularity, surface and translucent. The shader is loaded in the Luminance channel.

As you can see on the left picture, most of the texture has been ‘overwritten’ by the shader. That’s because I only loaded a color map in this test render. In the right picture I used an epidermal map and a subdermal map mixed together with a weight map. All maps are modified versions of the original color map.

This is how the luminance channel looked like after loading the different maps. The default color map is loaded into the standard Cinema Color channel.

I think the default c4d color channel is much easier to set up, so that’s why I left ‘Calculate Surface Shading’ blank. I used ‘Calculate Specularity’ to create an even amount of overall brilliance in the skin (see picture below). The standard C4D specularity channel has been used to create nice sharp specs on the edges (e.g. the lips and on the nose). Both specularity channels have been restricted to a map.

The final skin shader is made up of 6 different channels: Color, Diffusion, Luminance (with the Vreel shader), Bump, Displacement, Specular and Specular Color.

Scene

I quickly modeled a simple shirt, took it into ZBrush, divided it a couple of times and sculpted some cloth wrinkles with the Inflate brush. I also modeled the arms and shoulders and composed everything together in Cinema. There was no need to use displacements on the shirt; I simply exported the high-resolution mesh from ZBrush. I have a lot of memory, so I don’t have to worry that my computer might crash. There is almost no difference in render times between the low- and high-resolution shirt.

The texture for the shirt has been created by playing around with some filters and by using the ‘dodge’ and ‘burn’ tools.

Lightning

For this image I couldn’t use the Global Illumination system because Vreel Skin doesn’t work with GI, so I had to use standard Cinema lights. I created a 3-point-lighting with:

1) Main Spot @ 115 %
2) Fill Area @ 95 %
3) Rim Spot @ 190 %

I also include an area light (4) with very low intensity, placed below the model to simulate bouncing light from the bottom. All lights use soft shadows and ‘Falloff’ is set to ‘Inverse Square’.

Hair

Now comes the funny part: the hairstyle and the beard. I used Cinema’s hair module for this job. I created two additional maps: an alpha map for the beard and one for the hair. Both maps were loaded into the ‘Density’ channel of the hair objects. Unfortunately the density map will not take effect in the editor view. It will only be visible in the final render. So I would suggest setting ‘Display’ in the ‘Editor’ tab to ‘Hair Lines’ if you have enough memory in your computer.

I created eyelashes and a wet layer for the eyes. For the eyelashes I selected an edge loop around the eye, created a spline from it and pressed the ‘Add hair’ button.

Rendering and Post Production

The render with Vreel skin shader and displacement took about 4-5 hours (1h 30min without displacement). I rendered the hair and beard in a separate pass and composed both in Photoshop. Further more I rendered an Ambient Occlusion pass and multiplied it over the picture. I wasn’t happy with the way the eyes looked, so I copied parts of an eye photograph over the image. I finally did some color correction, applied Gaussian Blur to simulate DOF and added a grain layer. Here is the final image.

By Patrick Eischen

::GFXZoOM |source:3dm3.com

OK, this is a technique I picked up in a thread at CGTalk.com so I can’t take any credit for devolping it, and if you’re more than average in Cinema you probably know about it anyway. What we’re gonna do is make a segment of a tire, make duplicates of this segment, add a Bend deformer and drop the whole package in a HyperNURBS. I’m not gonna guide you throgh every single step but rather focus on the technique itself. You should be somewhat familiar with the functions of adding and bridging points.

Load the reference image in the Luminosity-channel and take a note on the size of the image. Then create a cube and give it corresponding values in the X- and Y-fields. Set Z to 1. Assign the cube the material with the default mapping type, UVW — you want the reference image displayed on the front of the cube so that you can work from the Front viewport and with UVW the image will place itself properly.

Then move the cube 1 or 2 units backwards on the Z-axis. Why? In the next step you’re gonna create a Polygon Object and start adding points and if you keep the cube at 0 on the Z-axis you points will be placed visually “inside” the cube. The points will be created at Z=0 and you don’t want that space occupied by the cube. So change the cube’s Z-position from 0 to 2.

Create a Polygon Object (Objects>Polygon Object). Nothing in your viewport will change but in the Object Manager a new Polygon Object is visible so double-click it and name it “Segment”. Switch to Front view, zoom in on the profile, make sure you’re in Points mode and that you have Segment as the active object. Now start adding points by selecting Structure>Add Points and then CTRL-click the outline of the profile. Just focus on getting the points down for one side of the profile since we will later mirror the Segment to get the complete element.

Place the points at the “crucial curves” of the profile — identify what features are giving the profile its shape and place the points accordingly.

When you have all points in place you select them all and clone them once — Structure>Edit Surface>Clone. Set Clones to 1 and change Rotation from 180Ú to 0Ú. Click OK.

OK, now you’ve cloned your points so don’t let go of that selection! Move the new points on the Z-axis only to -50 (or just type -50 in the Coordinates Manager). All points are at the same Z-value so moving them all att the same time will be OK at this stage. Note: the cloned points are the unselected ones in the image above.

Time to bridge the points. Select the Bridge tool (Structure>Bridge) or just hit B on your keyboard. The cursor will now look like an arrow with a small, black bridge. Click on the first point and start bridging. Check out this gif if you’re not sure on where to start, or read up on the Bridge tool in the manual.

This is roughly what you should have by now. Here I’ve dropped the Segment in a Symmetry Object just to see how it works. Now it’s time to start slicing using the Knife.

Select the Knife (Structure>Knife) or hit the letter K on your keyboard. Make sure that the option Restrict to Selection is unchecked in the Active Tools Manager — we want our cuts to slice throgh the whole mesh. From the Top or Right viewport add 4 cuts like in the image: 2 cuts to form a thin band of polygons and 2 cuts to form a slightly wider band. If you hold down Shift while cutting you will restrict the knife to 45Ú angles and will make it easier to keep the cuts straight.

Now switch to Polygon mode, select the polygons shown above and delete them.

This is how it should look.

OK, this can be a bit tricky but the principle is quite easy: select some points, clone and move them, and use the Bridge tool to create new polygons. Here’s how you do it:

Select the points on the image marked with purple dots (•) and copy their Y-value from the Coordinates Manager.

Now select the blue dots (•) and clone them once, just as we did before.

Paste the values you copied earlier in the cloned dot’s Y-channel and hit Enter — the points should move down to the position marked with orange (•).

Now Bridge the points to build the polygons nescessary for the pattern of the tire. The image above shows what it should look like.

Continue cloning points and then bridging them as this image shows. As you can see I’ve let 2 triangles slip through but I think we can get away with it

Now it’s time for some more slicing. Select the Top view and lay down 6 cuts along the X-axis as shown in the image. The cuts are made close to the edges and the reason for these cuts is to provide sharp definition when we eventually drop the finished wheel in a HyperNURBS. When you’re done cutting swith to Front view for some extra slices.

The black lines on the image indicates where the cuts should go. Once again, we want sharp definition on our tire pattern and this will get us there.

This close-up is just to illustrate that I decided to go with triangles for the ending of the thinner polygon band as well. You can also see some of the cuts we made in the previous steps.

If you drop the Segment in a Symmetry Object and hit render you should have something like the image on the right. It has some resemblance with a tire but we’re not there yet. Switch to Points mode and Top viewport.

Select the Live Selection tool and make sure that Only Select Visible Elements is unchecked. Then select a any group of 4 points and start moving the on the X- and Z-axes. If you have some reference material of real tire patterns, use them, otherwise just move and rotate the points (around Y-axis only!) until you get something that could pass as a believable pattern.

Frequently check with the Symmetry Object active and dropped in a HyperNURB to see how you’re doing. When you’re satisfied it’s time to Duplicate and then Bend.

Deactivate the HyperNURBS and select the Symmetry Object. Then select Function>Duplicate. The number of Copies determines the size of your tire — 5 copies will make it pretty small and 200 will make it pretty huge (although rather thin…). Anyway, enter 50 to start with and work from there. Alse check Generate Instances so you wont bog down your system with too much geometry. Also, if you change the geometry of your Segment, all instances will update immeadiately.Now, the tricky part here is to know how much every instance should move. Select Top view and start experimenting with different values for the Z-channel. You might wanna zoom in real close in order to get the instances to line up properly. I found that something around 2500 was an appropriate number. Click OK.

Add a Bend deformer (Objects>Deformations>Bend). Group the Symmetry Object (containing your Segment), the Instances and the Bend deformer under a Null Object (Objects>Null Object). Name the null Wheel. Select Right viewport and rotate the Bend deformer -90° around the X-axis/Pitch. Now double-click the Bend object to bring up its dialog box. Change the Y size so that it encompasses the whole group of instances and is placed reasonably in the middle of the group. Check Keep Y Axis Length and set the Mode to Limited.

Your hierarchy should be as the image above illustrates. Now we will bend all those instances into a circle and forming the actual tire.

Grab hold of the yellow handle on the Bend deformer and start dragging it in the Z-direction. You will see the instances starting to bend. You will probably have to drag the handle as well as zoom out quite a bit before the circle will be almost closed. Now zoom in and double-click the Bend deformer once again. You’ll see that the Angle will be very high and this is the value you should play with now — add 10-20 degrees, click OK and see what happens. Zoom in extremely close on the gap between the two ends and make sure that they meet as neatly as you can. For my wheel the angle of 412Ú proved to be OK.

Now drop the Wheel-group in a HyperNURBS and render — Congratulations, you have a tire! Just add a hubcap and you’re ready to roll!

Here I’ve added some additional cuts (the line along the center of the tire) to break up the pattern a bit plus a rim modeled by following this tutorial by Holger Schömann at Digital Worlds.

Note: the tire can get very heavy on the polycountside when you drop it in a HyperNURBS so if you’re not planning any close-up shots of it, deactivate the HN. Usually you can get away with simple polygons. Or set the HyperNURBS Subdivision Renderer to 1 to keep some smoothness.

::GFXZoOM |source:3dm3.com::