Illustrators are often required to produce magnificent and complex images within short deadlines and tight budgets. These images need to be flexible and allow for unexpected client intervention - colour variation, etc. Photoshop makes this easy, not only through its magnificent adjustment layers, but also by offering options for multilayering techniques and folder use.
Most abstract illustration requires the use of a 3D package at some stage, but it's impossible to imagine that one could achieve the exact look you're after solely within a 3Dapplication without any image manipulation applied to the final render. The difference between the initial render and the final image produced for this tutorial effectively shows the benefits of minimizing the time spent on modelling and rendering and instead focusing on reworking the image within Photoshop itself. Making slight changes to the Layer Blending modes or adding an adjustment layer may result in a huge visual change to your image and send your creative results on a completely different tangent.
So Photoshop becomes an integral part of the design/illustration process and enables you to present more options to your client. For this tutorial, you'll start by importing a rendered image created using a 3Dapplication of your choice.