Talented Amirhossein Erfani share with IT’S ART MAG his latest tutorial about car rendering, based on a scene shot done originally for the Hot Wheels upcoming movie.

Hello everyone! In this tutorial I’m going to show you how to come up with this shot, I hope you find this tutorial useful and can learn something from it.

I’ve done this shot as a 3d illustration for a movie (Hot Wheels, coming up) and it’s a little different from my personal works as in this case you’ve got to make your moves based on the script you’re given. As you can see it’s about a race between two super sports (a Lambo Réventon and a Ferrari Italia in this shot) and as it’s a “single shot”. There might be some good stuff and experiences that I’m more than happy to share with you all.
So, as for the beginning, I had to decide which camera angle to choose as it really matters to the Director, so before jumping into any high quality renders I decided to check the layout and the camera with the Director. For this purpose I did a few simple renderings in Vray and here’s what I came up with:

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The 3rd shot was chosen (but I personally wanted to go with the 2nd one! :D) and that’s it, we can advance to the next level. So, the models are 3d, but here’s the thing : you can either choose to do all the environment in 3d (which would provide you a great source for reflections, compositions and stuff – but also is very time taking) or you can make things in 2d and save a lot of time instead. I chose the second approach and I’m gonna share the experience with you.

So as for the environments, the very first thing we’re gonna need is the background, in this case a snowy road. After doing a lot of searching and some matte painting I came up with this road with cool snowy mountains at the background to kick start my work with. Next thing to do is to do the camera match and matching the perspective of your 3d models along with the background. I used a simple plane as the floor with a “Matte Shadow” material so that I can make the plot invisible but can keep the shadows to match my background.

This is the very basic render I did in max using a “Vray Light” as I needed the indirect illumination and soft shadows (according to the lighting which is a snowy-cloudy day) which by the way we need to modify our sky a little bit as well. For the car paint material I used “Vray Blend Material” , mixing two “Vray Materials”, one with a glossy reflection channel and the other with a more blurry reflection, mixed with a falloff map. Here’s the result of this basic render:

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That’s what we need to start the job with, but before going to Photoshop and make things happen, we’re gonna need a few more shots in 3d that will help us make progress. Here’s the “Mask” layer, very useful as we need to separate our 3d models from the background to be able to work on each separately.

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Here is the “Ambient Occlusion” shot that I made with Vray, it’s very useful when you need the indirect illumination and the soft shadows it provides us with.

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Now here’s the tricky shot. This is the shot that’ll save us tons of time and actually provides us with a good result. It’s simple, you cover the whole models with a simple white material and a Noise bump to make it like they’re all covered in snow. Don’t worry about the Snow shader and all that stuff, we’ll do things later in Photoshop.

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And here’s another shot that I thought might be useful. I used a “Cellular Map” in diffuse channel, maybe it can be useful for the parts that we have melting snow on the glasses or the areas that might be hotter, so it can look more like water drops.

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Yes, that’s crazy, but damn useful! Using the image itself in diffuse channel might be way too strange but very useful when blended in Photoshop. We definitely use an HDRI Sky map for some nice reflections and lighting, but this shot also provides us with some good reflections that we’re going to adjust and control later in Photoshop.

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After having all those shots, we import them all in Photoshop and start our job. The first thing I did was to separate the 3d models and the background using my Mask layer and I used a custom brush to add some smoke and snow in the layer between the models and the image. Feel free to experience and see what comes better. That’s why I call it a 3d illustration, as we use some basic digital painting techniques along with the multi-pass rendering technique.

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Using the same technique and by creating a brush for painting the snow I added some splashing snow near the wheels and I tried to follow the flow that is needed for the action and the speed.

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Added some foggy brush strokes to support the snow and also some “Motion Blur” to the wheels. Yes, I forgot to add the motion blur in 3d but no big deal, I used Photoshop’s Radial Blur filter with Spin mode to make the feeling for the spinning wheels.

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Now I told you that show will come handy! So what do we do? We simply add the masked layer of this shot right on the image, and instead of adding the snow, we simply remove the snow from this layer. Here’s a tricky tool, use “Background Eraser” tool instead of simple Eraser tool that gives you a cool rusty effect and is also very noisy. Just keep in mind to keep the tolerance parameter to a low one around 5-10.

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As you can see I’ve removed the part of the snow shot using the Background Eraser tool and kept some snow mostly at the low parts of the car bodies. As it actually is done in 3D and so it clearly sits on the model and respects the form, we can be assured that everything goes well. Just one thing, you might need to modify the layer by some dodge and burn to be sure that you don’t disrespect the lighting. I also added a simple color layer on the cars to put them more in the environment, as it’s not always about the background but also the Foreground, so it’s cool to cover the cars with some fog and stuff.

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I’ve used this approach before in this project I did for Dakar Rally 2013 (Desert Warrior 3 – credit goes to Rally Raid UK and Mike Jones for building the car) and here’s the thing : if you need a single shot image and can do things as easy as possible in Photoshop, so why bothering and using Unwrap to texture the whole model? Not only it takes a lot of time but it is also somehow useless as we need a “single” shot for the image. I Unwrap my vehicles only when it’s needed, which means that I’m going to need multi angles of a model and not a single frame. So we simply use multi-pass rendering with Dirt, Mud, Snow or whatever the shots are and we use simple UVW Mapping for these layers. I think you might find this method useful in some cases.

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So, back to the snowy scene. After adding the layers, snow, motion blur and everything, we’re going to need to add the falling snow itself as the last layer on the image, cause if you remember we had no snow falling in our original image. Again, it’s pretty much easier to add it in Photoshop instead of doing things in 3d with Particle Systems. Before adding the snow in Photoshop, I also wanna share this shot I did a couple of years ago, just to let you know that you can also do the particles in 3d, but again, only if it’s needed.

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Before doing that, it’s important to emphasize the subject of the image which are cars, and to be more specific the Lambo which is in the front section of the image. So when we’re adding such details it’s better to make them serve our subject. I created a simple brush for adding the snow but I added it in a direction that also can make a good feeling for the composition. Here’s the first layer of falling snow I added using the custom brush I made for this purpose, and as you can see I added it so that it can serve the flow of the image as well. Also, I used the “Radial Blur” in Photoshop (Zoom) to add some motion to the particles as well.

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And here’s the second layer, again with Motion Blur (Zoom) added to create the motion and the flow.

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As I needed another angle for this shot, I also did a “Side” view version of this image, using the same exact method with the same models.

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And here’s the final result:

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Thanks for your time, I really hope you found this tutorial useful. Enjoy your art, feel alive and drink the good stuff!

Visit Amir’s garage (portfolio) here: www.amirhossein-erfani.com
Get in touch with Amirhossein via Facebook: www.facebook.com/erfani

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