To do this, I checked that the shadows and occlusion were on in Render > Render Properties, then just pressed that tiny little BPR sphere on the top right corner of the screen.
When I finished the rendering, I went to Render > BPR Render Pass and saved the passes by clicking on them. I ended up with the following passes: Render, Depth, Mask, Shadow, and AO.
The process thus far was good, but not good enough, so I decided I needed more passes.
I decided I needed a Rim light pass. To do this, I went to the Light properties once again, and this time applied a stronger light (with an intensity of 10). I also moved it behind the object by clicking on the sphere to take the light backwards, and then applied the Ambient setting to 3, and the Distance setting to 100.
To save time I didn't render it, but simply grabbed the document (go to Texture > Grab Document) and then exported it (Texture > Export).
I still needed another pass (the Reflection pass), so I assigned a Reflected map to my sculpt, and completed the same steps as before to export the image.
As the rendering process was complete, I was ready to start the sweet post-work steps. For this, I closed ZBrush and opened Photoshop.
First, I imported all the passes as separate layers with the main pass at the lowest layer. I then made a mask for them from the mask pass (using Magic Wand to select the white areas).
At this point, I made all the passes invisible except the main one, simply for ease of use. I made a layer below that one, filled it with a bluish gradient and named it 'background'. I chose blue because it complemented the yellowish color of the robot well.
I still hadn't painted the major textures on the sculpt, so I pasted a new scratch layer on the above layer and used the Depth pass as its mask, changed the Blending mode to Overlay and the Opacity to 55. I then manipulated the Reflection pass with Curves and Saturation and changed the blending to Soft Light and the Opacity to 100 to bring a nice reflection to the image.
After changing the Blending mode
After the manipulated Reflection pass
After this, I began to add some shadowing. First, I brought down the AO and Shadows passes, and set the blending to Multiply. I also duplicated the main render on the high top and masked some sections to create the highlights.
I still wasn't happy with the color, so I inserted the BPR render pass on a new layer and manipulated the colors by using Hue and Saturation and changed the blending to Color. I also added a Color Lookup (Edgy amber) to refine the color.
Next I decided to add the lighting. First, I added the rim light and manipulated it by using Curves to darken the shadows and applied a bluish color using Color Balance. I added that on top of the layers in Color Dodge mode and made a duplicate in Screen Blending mode.
As you can see below, it looked much better, but still lacked a sense of depth. To counter this, I added a solid blue color with the inverted mask pass as a mask. This helped the robot match the background more convincingly, and gave a better sense of depth.
Finally, I played with the color adjustments a little more and filled the eyes with a solid white block and then added some ready-made flares that I found around the net.
I also added some smoke rising from its collar by painting them in with smoke brushes. Finally, I added a vignette to make it look even better. Here is the final image!
See more of Mohammad's work over on his site
This making of was featured in issue 94 of 3dcreative...