Materials and Lighting
The materials I chose were basically simple and clean. Chrome was used for the joints and rivets, rubber for the hip junction and a basic orange, blurred metal for the rest of the body.
The layout of the scene was pretty simple too. Basically I recreated a white photographic studio set with rounder corners, a luminous polygon and a HDRI. The luminous polygon really makes the difference as it creates a nice diffuse light, and at the same time adds a nice reflection to the model that highlights the shape and adds more depth to it. The HDRI was very subtle, but did enough to add small reflections on the rivets and eyes too. I chose a vertical format for the image to match the shape of the robot (Fig.07).
Post Processing and Color Corrections
Once the final render was complete it was time to do some work in Photoshop. The final render actually looked very nice, but when I thought about the original concept it was clear that the render didn't have the vintage look I wanted (Fig.08).
I thought that this could be fixed with simple color adjustments so I researched vintage photos and found examples of the type of image I wanted to create. I noticed a color gradient that seemed similar in a lot of the photos, so I tried to apply this to my image. To do this I used Curve corrections as they give you more control than if you just use the Color Balance tool (Fig.09).
Due to the anti-aliasing the rendered image lost some sharpness in the final output. To fix this in Photoshop I used a High Pass filter. The High Pass filter finds the most contrasting areas of the image and masks the rest with a 50% gray. The higher the pixel radius is in the filter panel, the sharper the image will be. After creating the high pass mask I set the blending mode to Hard Light to enhance the general reflection on the image, especially on the chrome (Fig.10).
The final step was to create a nice gradient in the shadows. I used an orange/blue gradient over the image and set the blending mode to Soft Light. This mode is similar to Overlay, but more subtle and useful when working on shadows. These notes about blending modes are not absolute rules and cannot be applied to every image; the key is to test the modes and see what works for you. When this was done the colors looked nice and I was happy with the image (Fig.11).
It's not very easy to describe the creative process behind a 3D image as every step is made up of many more small steps, but I hope that in some way this tutorial is helpful to you and that you enjoyed reading it.