Motorcycle Rendering Tutorial for Photoshop, creating a 'photoreal' 2D motorcycle

For the wheels (rims) we will use exactly the same process. I have imported the curves from Rhino and created a couple of layers for the black areas as well as the blue areas.
For complex assemblies like the rims and disc brakes, it is wise to create not just new layers, but also a new layer group. You can then put all the layers associated with each assembly in their own group. When you select a layer group you can scale/move every layer in that group at the same time. Very convenient!

Now we'll scale the group I created for this front wheel and put it into place using the uniform scale and snap approach I outlined earlier on.

Ok, now that we have these panels coloured we need to give the edges some nice highlights. Since we have paths for most of these surfaces this is really easy.
Select the path of the surface that you want to edit with the Path Selection Tool (A) and click the 'Load path as a selection' button at the bottom of the Paths display (you can chose multiple paths if they're not overlapping or anything, you might as well do a couple of those at the same time).
Make sure that you're on the correct layer (I just paint those panel highlights on the colour layers, no need really for a seperate layer for highlights) and also make sure that the layer is still set to 'Lock transparant pixels' as we don't want to paint the highlight outside of the panel area.
Now we're going to adjust our selection; Select > Modify > Contract... I chose to make the selection contract by 2 pixels. Now inverse your selection (Shift + Ctrl + i) and we're ready to go. Since we're only allowed to paint between the selection border and the outer edges of our panels (because of the pixel transparancy lock) we can chose any brush size we want to paint the highlights. Just make sure your brush isn't too big for the areas where you want to end the highlights, say near the corners of your panel.
Panels that are located high above the ground we're going to give a strong highlight at their top edges, panels that are located just above the ground we're going to give highlights on the lower edges as well because of the light bouncing off the floor.

Here's the result of that highlight work we did. Notice how the main panel in this screenshot has a highlight on its top edge that seems to suddenly stop. The reason for this is that there are parts above that panel that stop it from catching the light there.

A stupid mistake I noticed here is that I completely forgot about the core shadows on this thing. Without them the image looks really artificial and flat.. never do the highlights without forgetting about the core shadows.

You can see a variety of things in this close-up. First of all, the tire profile. Again this was made with 2 simple Rhino curves (inner and outer shapes) that I polar arrayed and imported in Photoshop. The colouring of these profiles are actually pretty simple. Use the magic wand tool to select the inside bits of these shapes (make sure you are on the layer of your profile curves you imported) and with a small black airbrush drop in the shadows and with a white one the highlights. Having selected the insides of these shapes makes sure that you don't colour outside the lines

Something else you'll notice is that there's a big difference in the darkness between the steering arms and the black bits of the brake disc assembly. I corrected this in the brake disc parts by playing with the brightness/contrast sliders.

Now it is time to reflect on all our hard work so far.. we have finished the rendering for a large part. All our surfaces are coloured and all our details are in there. The only thing is that it we still need to add the reflections.
All the body panels still look as if they're made from a dull plastic. We need to add a clear coat on top of it to make it shine!

To keep things clear and non-confusing we'll create a new set of paths in the paths window as you can see in the image below. We'll use this new set to create our reflections.