Making Of 'Curvy VW Bug'

Research

It's been years since I had the desire to model a cartoon car; I remember spending hours browsing all the images from the 3DTotal gallery looking for inspiration, and each time I laid my eyes on a car I would feel more and more inspired to make my own. That was how I ended up making plans to build a Volkswagen Beetle - also known as "Fusca", in Brazil.

Concept Art

At first, my basic idea was to build a destroyed police car, filled with bullets and guns. But as soon as I modelled the front hood and did a test with Maya's "mi_car_paint" from Mental Ray, I decided to make a red, curvy and shiny Beetle. I don't think there is any other car as round and curvy as the VW Beetle; cartoons are all about curves, nothing is straight or square, and so this car was the perfect candidate for this project because every piece of it is rounded.

First I made a drawing of the side view of my car, starting with a sketch of the average shape of the original Beetle. Then I started changing everything that I could, making it even more rounded. I exaggerated the sizes and worked on a stronger, curvier concept.

Modeling

Once I was happy with the sketch, I jumped into Maya and started modelling the overall shape using basic Box Modelling techniques, with the help of lots and lots of splines to set up the proportions correctly, because I didn't have the top or the front view, only the side sketch.

Having these lines as a 3D reference for the overall structure, I started modelling piece by piece using box modelling techniques, taking advantage of Maya's Smooth Mesh preview.

To use the Smooth Mesh preview feature, just start modelling anything with polygons and then press the 1, 2 and 3 keys to view the low and high smoothed versions on the fly. Once you are happy with the object, you will have to convert the mesh: click on Modify, Convert, and select the option: Smooth Mesh Preview to Polygons.

The low polygon version of the Beetle ended up having a total of 10,819 faces, and a total of 232,000 faces once it was mesh smoothed on level 3.

After I had all the lines adjusted for a perfect idea of proportions and spacing, I started looking at my references and modelling the most important parts of the car, like the door, hood, trunk, front, and structure. The best approach when car modelling is to model separate pieces, just like it is done in a real factory, so you can achieve nice dents between pieces. Since this was a cartoony version of the Beetle, I decided to exaggerate the dents.

Once everything looked "right", I started modelling all the accessories and every little piece, like the tyres, windows, rubbers, head lights, turn lights, wind shields, door handles, plates, antenna and so on.

Texturing

The red shader wasn't too difficult to approach; I used the Mental Ray "mi_car_paint" node. To create one, just open the Hypershade, go to create, mental ray materials, and select: "mi_car_paint_phen".

All I needed to change was the 'Base color' and 'Lit Color', to get something more red and orange with the reflections. This node has special options to setup a 'Flake Color' and 'Flake Weight', so you can fake different kinds of car paints. For this scene I went for a white Flake just so I could get better results with the lighting.

There is nothing too fancy about the glass texture; all I did was set a .250 reflectivity and 80% transparency, and the rest is all waiting on the quality of my HDR lightning and reflections. I started with a Global Illumination + Caustics settings, but after rendering a few passes of both versions, the "simple glass version" was looking much better.

The metal was default as well; just a normal blinn with .400 reflectivity, low diffuse, low eccentricity with a high specular roll off,  and a dark grey for the colour.

Lighting

The lighting was very simple; just one point light to generate the shadows and a sky dome with an HDR image to render the environment, reflections and to light up the scene in general.

Rendering

After everything was finished, I started tweaking the render settings for better quality shadows and glass reflections. The overall tweak I made rotated the sky dome in order to get a good reflection from the HDR image, and I also added a floor to capture the shadows on my shadow and occlusion pass.

The final image, as well as all the render passes, was rendered using Mental Ray. The settings were simple: Final Gathering was on, with Accuracy: 200; everything else default. The Raytrace/Scanline Quality was set to adaptive sampling, min 0 and max 2. The rest was all default, as well.

To render an occlusion map, first of all select your camera, go to environments and change the background colour to a full white. Select all the pieces of your scene - in my case the entire car plus the floor - and then add the node "surfaceShader" to them. Create one Ambient Occlusion shader; to do this, on the Hypershader go to: Create, Mental Ray Nodes, Textures, "mib_amb_occlusion". Connect the "Out Color" of the node you just created to the "Color" input of the "surfaceShader". That's all! Now you can render the image and save the result as Tiff or Tga format.

Render Passes

Usually I render a few different passes of an image in order to be able to tweak the overall look without having to re-render the entire scene. First I render one pass of each kind using just one light with the HDR image, like: Shadow, Beauty, Occlusion and Diffuse. Then I try different settings with several lights in order to get a high range of images, so I can merge them all in post production using Adobe Photoshop, or Adobe After Effects for animations.

Conclusion

I spent one or two weeks working on the sketch and modelling all the pieces, plus several weeks working around major problems with the lights and re-designing a few parts of the car just by eye in order to make it look "right". Once it was almost finished, I went forward and modelled the insides as well, like the seats, driving wheel and mirror.

The final result became my favourite and best work, so far. The funny part of this project was that I almost gave up! There was a moment when nothing seemed to be working; the lights didn't work as I expected; the HDR and reflections weren't looking as I wanted; the occlusion map was not helping at all; the car shape wasn't looking as I wished it would... but thankfully, I didn't give up - I kept trying, re-designing and experimenting with different settings, even when my own mind was telling me it was a lost project, beyond repair. At the end, I found my balance between the shape and lights and was able to conclude the image.

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