Master MODO portraits: Learn to paint convincing image maps
3D Artist Bert Heynderickx - aka Alberto Ezzy - reveals how to create image maps for texturing skin and clothing using MARI and Photoshop in the second part of his tutorial series
See Part 1 of this tutorial series: Perfect the geometry of a male head
In Part 1 of this tutorial series we looked at the creation of a male head portrait in MODO, revealing how to use the Sculpt Tools in MODO to clean up the geometry of scanned head data, as well as adding and modifying a hat model to perfectly fit the character.
Now in Part 2, we will move on to use MARI and Photoshop to create the different image maps needed to feed the Skin Shader in MODO.
Step 1: Epidermis Diffuse Color Map
This is the main image map that is delivered with a scanned model from Ten24. It's the base for almost all our other maps. I like to import this map into MARI and derive and paint other maps from it. This is quite a large map, so it's important to have a powerful graphics card, such as the AMD FirePro™ W9000. Because of its large, dedicated memory and generous memory bandwidth (264 GB/sec) via the PCI 3.0, painting in MARI is incredibly smooth.
I select the first layer and rename it ‘Diffuse Color Map'. Right-click and select Import/Import into Layer. To be able to import images in MARI; the file has to have a certain naming convention. So you have to rename it to something like 'Skin.color.1001.tif'. According to the UV offset system in MARI, called ‘UDIM', this is the first ‘tile' in the UV grid. The '1001' refers to the first position the map needs the be in UV space.
Now, with this image imported and applied onto the model, let's paint away the parts of the hair cap that might be peeking from under the hat. For this, I select the Clone Stamp tool. It lets you copy parts from your image to the surface of your model. First you set a source point by CTRL+LMB (Control Button + Left Mouse Button). Then you can clone just like you would in an application such as Photoshop. I clone parts of the hair over the border of the cap.
Step 2: Epidermis SS Color Map
The Skin Material in MODO has 3 different layers: an Epidermal layer, an Upper Dermal layer and a Lower Dermal layer. First let's make an image map for the Epidermal layer.
To keep things organized, I copy the Color Channel in MARI and rename it ‘epidermis'. Now I need to desaturate the base Diffuse Color map. So I add an Adjustment Layer and choose HSL (Hue-Saturation-Light). I lower the Saturation to about 0.600. Next I add a Layer Mask and, with the color black, I paint a mask to recover a bit of Saturation on the ears and eyes of the model.
I like to use the Supersoft Brush Preset for this kind of work. The only thing left to do now is to export this result as a flattened image map for use in MODO. So right-click on the ‘epidermis' channel and choose Export Flattened>Export Current Channel Flattened.
Step 3: Upper Dermis SS Color
Next let's make the image map for the Upper Dermal layer. I copy the Color Channel in MARI and rename it ‘upper dermis'. This map has to have a nice fleshy pink tone, and some increased contrast.
To add some contrast to the base Diffuse Color map, I add a Contrast Adjustment Layer and set it to about 1.300. Next I desaturate it a bit with a HSL Adjustment Layer at 0.750 for the Saturation slider.
I add a fourth layer and change the Foreground Color to a fleshy pink and select Patch>Fill>Foreground to fill the whole layer with this chosen color. I set this color layer to Multiply at 0.500 to combine it with the underlying layers.
Then I add a mask to mask out the eyes, brows and hair so they don't get the pink tint. Last step is to export the flattened channel as described in the previous step.
Step 4: Lower Dermis SS Color
Next, let's make the image map for the Lower Dermal layer. I copy the Color Channel - which holds our base unaltered map - once again, and rename it ‘lower dermis'. This map has to have a reddish tone and quite some increased contrast. This is achieved by adding a Contrast and a Levels Adjustment Layer.
Notice that this is a completely non-destructive workflow. Whenever I feel necessary, I can change the values of these Adjustment Layers or even toggle them off to get back to my base, unaltered image map.
Step 5: Oil Specular Amount
Now I need to create a map that can tell the Skin Shader in MODO where the oily parts of the skin are. Those parts will be shinier than others. These include nose tip, eye bags, ears, chin and, in lesser extent, forehead and cheeks.
I start by creating a new channel, just to keep things organized, and paint the parts of the face - that I just mentioned - with a Supersoft White brush. You will definitely get the best results when you do this with a tablet and pen stylus. Next, apply a very dark gray layer behind the white parts to finish the map (please refer to my Pro Tip at end of this tutorial). Export, as mentioned above.
Step 6: Oil roughness
This map defines how tight the specularity is that we defined with the previous map. I want tighter specularity on the lower eyelids, the tip of the nose down to the corners of the mouth, and a bit looser under and between the eyes, the ears, the lips, and the chin. So let's paint that in - once again with the Supersoft Brush.
Step 7: Normal Map
The original scanned model from Ten24 was delivered as an OBJ and a ZTL file. From the ZTL file, you can extract a Normal Map in ZBrush and export it for use in MODO. I had to do a ‘Flip Vertical' in Photoshop to get the right orientation of the map. This Normal Map has all the fine detail that was originally scanned such as pores and irregularities in the skin.
When we apply the Normal Map together with the Bump Map later on, we will get fantastic and realistic details. Here's a screenshot of the Normal Map Window in ZBrush and a detail of the map:
Step 8: Bump Map
Okay, let's make the Bump Map in Photoshop next. Open the original image map (the diffuse color map). A bump map doesn't need any color, so we can desaturate it. Choose Image>Adjustments>Desaturate.
Next we apply an Unsharp Mask filter (see screengrab for all my settings). Now copy your Base Layer and put it above the sharpened layer. Then choose Image>Apply image. Select the underlying layer as the Source Layer, check ‘Invert', change 'Normal' to ‘Add' and set ‘Scale' to ‘2'. Now invert this result by selecting Image>Adjustments>Invert (Ctrl+I).
We now need to apply a very extreme Curve Layer to bring out all the details and contrast even further, and a Levels Layer to increase the lightness (see screengrab for all my settings). We don't want the detail inside the nose and the eyes, so they get painted over.
Step 9: Shirt and stains
I'm using a nice tileable fabric texture that represents a T-shirt like feel. When applied with a UV map, I like the result, but I find it a bit too clean. So let's make it dirty in MARI. The perfect set of brushes for this is located under Shelf>Hard Surface Brushes. So first, import the shirt's geometry in MARI, and create a New Layer. Paint the dirt and stains. Make sure you export only this layer by right-clicking and choose Export Selected Layer. This gives you freedom to choose how much you Multiply it over the shirt, when you apply the map in MODO.
Step 10: The hat
For the hat, I choose a tileable map of dark denim and make a bump map of it by desaturating and adjusting the Curves to make it lighter. In the next tutorial (coming soon!) I will apply all of the above maps in MODO. We'll also take an in-depth look at the Skin Material and different aspects of the Shader Tree.
So this concludes the image map part of the work done on The Fisherman. Next time we'll take a look at how to apply all these maps in MODO. Stay tuned!
Top tip: The difference between black and dark gray
If the background of the Specularity map is completely black, the specularity of those parts would be zero. By assigning a dark gray as the background, the whole face starts with a very light amount of specularity - which is more realistic - over which the parts with higher specularity are painted!