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Create a Rusty and Worn Metallic Textured Skull Using 3D Renders

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Photoshop is a fantastic tool to help 3D artists save time and improve the look of their renders. In this tutorial we will demonstrate how to combine ZBrush materials and lighting render passes to create a stunning metallic textured skull. Let's get started!


Tutorial Assets

The following assets were used during the production of this tutorial.


Before You Begin

While this tutorial uses both Photoshop and Zbrush, we won't get too in depth with the Zbrush steps as 3D isn't the focus of this site. If you would like to learn more about ZBrush, head over to our sister site Cgtuts and have a look at their ZBrush category. For the purpose of this tutorial we have included PSD files that were exported from Zbrush so that you can follow along with the Photoshop aspects of this tutorial.


Step 1: Composing the image in Zbrush

For the first few steps, I’ll give you an explanation of what I did in ZBrush. I won’t get too in-depth as that isn’t the focus of this tutorial. I sculpted the models and placed them on the viewport in the position I wanted them to be rendered. In this case, I composed the image using the 2.5D capability of ZBrush. Then, I dropped the different tools on a 2.5D canvas, moving, scaling and placing them into the right position. I don’t usually like to make preliminary sketches. I do most of my work directly on the canvas.

Make sure to set your canvas size in ZBrush as twice the size as you want your final image. Then, you can use the AA button before exporting the image for good anti-aliasing results.


Step 2: Settings materials and light in Zbrush

For this image I set two different lights, global and rim, and three materials, two for the metal, one for the textured worn finishing, and other chromed, and one more material for the bone part. I also used a flat material render for use it as a mask to isolate the background, which we use later.


Step 3: Start composing in Photoshop

Zbrush exports documents as PSD files by default, then I open one of the materials renders and start adding more layers.

My idea is for the skull to have a worn metal effect but over a polished surface, as if the passage of time has added layers of dirt and rust. So I added a new layer with the image of textured metal on top of the “chrome” later, after that I copy the same layer, right click > duplicate layer, and set the blending mode to Hue and adjust the opacity to 50%.


Step 4: Adding some destruction

In this step we are going to make the "tricky" part of this image, add a Layer mask to the "Texture" layer and use a textured brush (no300, no400, or no250 brushes from the assets) and black color to paint on it, thus create the scratches needed to reveal the chrome surface and give the effect of worn metal layer.

After that, we are going to add the shadows to highlight even more stains and create more surface realism, for that we will add a Layer Style to the "Texture" layer as a Drop Shadow as shown in the picture.


Step 5: Adding the bone part

For this part we need the bone material render from ZBrush. Put it on top of the rest of the layers and name it "Bone," then we have to make a mask to reveal just the part that we want, add a Layer mask to the "Bone" layer and paint it with black. I used the Brush Tool (soft round brush) because it is a small and regular area that is easy to define.


Step 6: Adding some texture and shadows to the bone part

To add texture to your surface, use overlapping layers set to soft light. You can vary the opacity depending on how much you want to emphasize the effect. In this step, I used texture brushes with a layer mask. You can also use the burn tool using a textured brush to apply the desired effect.

Then, I added a new soft light layer set to 35% opacity and painted in some black using a textured brush to add some irregularities to the surface.

I then created the “bone shadows” layer and set it to multiply at 100% opacity to paint in some shadows into the eyes.

To avoid painting on undesired metal parts Copy and Paste the same Layer Mask that we used to isolate the bone part.


Step 7: Adding the secondary light

I usually like to add a secondary color source light to add some atmosphere to my images, it enhances the feeling of location and add strength to the image impact.

Then I add the rim light render from Zbrush as a new Lighten layer "Rim Light"; when I am building the image, I usually don't have very clear idea of which kind of scene I want to render, then I play with the color of that light, Image > Adjustments > Hue/Saturation > Colorize, and I see how it works with different color schemes, the result will influence on the final mood of the image.

In this case I set the color to a red light which is coming from below, then I add a Layer Mask and paint a gradient from top to down to turn off the light on the upper part, I set the opacity of the layer to 75% to integrate it a bit more.


Step 8: Adding the background

Add the background that we included in the assets above and apply a layer mask as shown below using the ZBrush mask render.


Step 9: Integrating the background

To integrate the background we are going to need to add some layers and adjust their blending modes. Add 3 news layers as shown in the layer stack in the screenshot and apply a layer mask as shown. You can then paint highlights and shadows using white and black colors using the layer’s opacity to adjust the lightness/darkness of the layer.

Next, we are going to integrate the cables with the background. Create a new layer, name it "Background shadows" and change the blending mode to Multiply, 100% opacity, then do as before with the Mask layer, copy it and apply it to this new layer, and with a soft round brush paint some curved strokes to achieve the cables shadows.


Step 10: Adding some steam effect

The brushes found in the tutorial assets above includes some very interesting smoke, cloud, and fog brushes which we are going to use to add some toxic steam.

Create a new layer and name it “Ambient steam.” Se the blending mode to normal at 100% opacity and paint some strokes with brush number 566 onto the lower part.


Step 11: Toxic juice

Here we add the toxic liquid that drips down from valves, add a new layer, name "Toxic liquid", blending mode Overlay 100% opacity, we need a soft round brush, adjust size to fit stroke to the valve exit, pick a bright green color and paint from there to down, keep pressed the Shift key to have a straight line while you trace, after that, use the Erase tool, with the same soft round brush, to remove a bit of the lower part, use this tool adjusting opacity less than 100% to fade it down.

Now we are going to add some toxic vapors and add some brightness to the toxic liquid, create a new layer, name "Toxic vapor", blending mode Normal, 100% opacity, pick brush number 300 Rising smoke, and with the same green we used before paint some vapor clouds coming out from the valves, then we repeat same process as before, soft round brush, pressing Shift key and paint a straight line, in this case decrease a bit the brush size and pick a lighter green.


Step 12: Merge Layers

When I have a considerable number of layers I like to "restart", merging them and have a new base to work with, but I keep original layers for future changes or corrections if necessary, keeping them organized in a group folder.

Then select all the layers, duplicate them, and merge the duplicates together. Name the new layer “Toxicskull.” Now place all the unmerged layers into a group as shown below.


Step 13: Levels and color corrections

Let’s add some adjustments to this piece by adding adjustment layers. You can use your own judgment here in terms of settings.


Step 14: Start adding light sources

To add some atmosphere, create a new layer and name it “red light.” Set its blending mode to normal with 80% opacity. Use brush number 300 rising smoke-1 and paint some fog in the bottom left corner.


Step 15: Adding more light sources

In this step we are going to add another light source. Add a new layer, name it “top light.” Set blending mode to Lighten with 55% opacity and apply a white to black gradient as shown.


Step 16: Adding metallic highlights

Use the Dodge tool to lighten up areas that you want to add highlights. Then, on a new layer use the number 500 Flare brush to paint in some flares. Use different brush sizes depending on how big the reflecting surface is.


Step 17: Adding extra shadows

In this step we're going to add some extra shadows to give some parts more depth and detail. Here, for example, I see that screws need some shadows, then I add a new layer, named "Extra shadows." Set to Multiply blending mode, at 40% opacity, pick the Brush Tool and with a soft round one and black color paint shadows where necessary.


Step 18: Add impurities to air

To add some impurities into the air, use brush number 200, the Ash brush, it works very well and I use it a lot. Add a new layer, named "Impurities," Normal blending mode, 100% opacity, pick pure white color and paint in those areas where the light has more intensity, light illuminates those small particles floating on the air, paint using different brush sizes.

But this is not enough. We will add an extra effect to our atmosphere, create a new layer "Impurities copy", paint a bit more with same brush, but now try to choose areas where light is visible, then apply a Gaussian Blur to the layer, Filters > Blur > Gaussian Blur, a small amount 1.2 pixels is ok, with this extra step we will add a sense of depth to the image blurring air particles which are closer to our point of view. One tip is, if you want to remove some of this particles erasing them, pick a kind of brush with a shape of cloud, fog, smoke, etc.


Step 19: Vignette

I usually add a vignette to my images; I think that it adds an extra of bit of attention and strength. To do this, make a selection of the entire image using "Backgroundl" layer, Command/Ctrl + left click on the layer, then add a new layer, name "Vignette" Normal blending mode, 100% opacity, and stroke that selection, Edit > Stroke, use black color, 6 pixels wide inside, then blur it, Filter > Blur > Gaussian Blur, and apply a big amount, over 30 pixels is fine.


Step 20: Refine jagged edges

To refine the ant- aliasing, grab the Smudge tool and adjust it in two ways, set the Strength to low values, between 1 and 5, and adjust brush size very small, between 5 or 9 pixels. A soft round brush will work well, and smudge the edge doing several passes always following the direction.


Step 21: Add depth of field

There are different ways to add depth of field to an image, in this case we are going to apply it manually, because the only part I just want to blur are the background wires, grab the Blur Tool, adjust Strength to 30%, and blur them softly.


Conclusion

I like to finish my images with one last layer, the noise layer, I add it for two reasons, one, I like the noisy surface, and it helps to homogenize the entire image, integrating the background with the extra painting layers added during process.

Create a new layer named "Noise." Set blending mode to Multiply at 100% opacity, fill it with white and go to Filters > Noise > Add Noise. Set noise to 12% or whatever looks best.

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