How to use Photoshop for postproduction

Thanks go out to Nacho Riesco Gostanza for this Photoshop tutorial. You can see more of his work at www.riesconacho.wix.com

01 Add textures in ZBrush

We will texture the model in two ways: by polypainting and adjusting the material’s settings. First fill the model with a light yellow colour as a base. Then, using Alphas and browns, spread some stains to emulate the shell’s surface. Use the Cavity Mask option on the Masking subpalette to darken the wrinkles and depressions a bit.

Now let’s tweak the material. Here I used the default: SkinsShade4. The technique is to add extra detail and colour to the model’s surface using an image loaded on the Surface Bump picker. Import that image as an Alpha on that picker and adjust the Canvas Bump size slider, so we will have a fake geometry based on the Alpha texture that’s applied to the whole canvas. Now, choose a colour for the Cavity Color Picker and adjust Cavity Colorize, Cavity Radius and Cavity intensity sliders to colorise the cavity surface. Check how it affects the material in the Material Preview and use the Best Render to check the result.

 

02 Import render passes

Still in ZBrush, use one white sunlight as a main illumination and a Lightcap for the blue reflection. Then render the image using Best Render first and BPR after. On the BPR I rendered the model without shadows – I also exported a Flat Render. Now in Photoshop, import all the render passes we created in ZBrush: Ambient Occlusion, Shadows, Image (without shadows), Mask, Flat and Depth renders. Manage layers as shown and place Depth pass on the Channels palette.

 

03 Enhance the texture

Let’s start with the Photoshop editing. To enhance a bit of the render’s texture, we’ll use the Flat Render Pass (Polypaint). Set it to Multiply layer blending mode and decrease its Opacity to 85% – now we will have a sharper stains texture. In some cases it’s a good technique to adjust the colour of that layer to add more tone variations to the surface using a Hue/ Saturation adjustment.

 

04 Insert shadows

Now select the Shadows layer and change its blending mode to Multiply. Repeat the Hue/Saturation adjustment, as mentioned in the previous step, activating the Colorize option. We will colourise shadows according to the environment light – in this case I opt for blue, which is the same as one of our render lights. Adjust the opacity of the layer to reveal the surface a bit.

 

05 Bring in colour and texture

Next we will modify the colour surface and add more texture. Photoshop enables you to enhance a lot of renders using different blending modes and painting techniques. It’s handy to have a decent stock of custom brushes to achieve different finishes and effects for this step.

First we create a new layer, place it over the Polypaint layer and underneath the Shadows layer. With an orange tone we paint some strokes on the shell’s surface to blend them with the surface. Change the layer’s blending mode to Color and adjust its opacity to get better integration. Now, adding another layer, include more stains and imperfections with a black colour. e Change the layer’s blending mode to Overlay and set its opacity accordingly to suit.

 

06 Apply the background and DOF

In order to add the background, it will be necessary to add a mask. This render pass will be useful to make quick selections differentiating the model from the background. Using the Magic Wand tool, select the shape of the shell and then use the selection to create the layer’s masks – one for each active layer. Place a new layer below the rest and fill it with the desired colour. Here I added two additional layers – one to create the blue texture and the other to fade it a little with the gradient. Next, duplicate all the layers and merge them. Finally, using the Lens Blur option, add the depth of field effect. For this we will use the Depth channel we exported from ZBrush, selecting it on the Lens Blur Source selector.

 

Sculpting the model

This shell model is a good candidate to sculpt using the default 3D meshes you get in ZBrush. 3D meshes are good allies to start sculpting simple forms that enable us to have a good base for our model or specific subtool.

In this case the Spiral 3D will be perfect. Before converting the mesh into a polymesh, we will have the chance to transform the properties of it using the initialise subpalette that you can find in the Tool menu.

Each 3D mesh has its own settings to play with – this means we can change the settings of the mesh to suit our purposes, setting its form, coverage, mesh density and so on. When you’ve achieved the desired form, convert it to polymesh and it’s ready for sculpting.