Digital Technologies in Car Design - Part 1: Digital drawings and 3D renderings

Digital Technologies in Car Design - Part 1: Digital drawings and 3D renderings

  

The first of a series of articles about the new technologies in car design. A brief survey of digital paintings and sketches, 3D models and photorealistic renderings, the new automotive design communication forms.

The digital technologies have a great impact not only on the vehicle engineering development, but also on the creative process. Digital renderings and sketches, 3D models, photorealistic images and virtual environments are the new communication forms of the modern Design Centers.

Car manufacturers invested a lot in digital technologies that help them reduce the development time, both for production cars and concept cars. This is one the main reason why the number of prototypes has grown so rapidly in the latest years.

Digital Drawings

Even in our modern era, the first expression of an idea for a new car, or more in general for a new product, is a hand made sketch, drawn with pencils or pens.

It is difficult to think that in the future a new digital technique will replace the traditional media under this aspect, anyway the digital painting techniques are more and more used from the first phases of the design process.

They can be used to simulate the conventional media or to create images with a “digital” look: the latter represents a new form of expression for the designers’ creativity.

The basic tools of digital drawing are a PC, a painting software and an input device: the most common is a graphic tablet.

The most used software are Adobe Photoshop, the standard application for photo editing, which is also suitable for digital painting, and Corel Painter, a more specific software that simulates the traditional media.

A more recent entry is SketchBook Pro from Alias, a cheap and easy-to-use tool to sketch and annotate ideas.

Designer at work on a graphic tablet	A Mercedes designer working with the traditional media: markers, pencils and chalks

A designer drawing directly on a Wacom
interactive pen display (Mercedes)

The professional graphic tablets are pressure-sensitive and can recognize up to 1024 pen pressure levels; the resolution of the drawing surface can be higher than 5000 dpi: this means that the designers’ creative and artistic technique can be expressed with no limitations imposed by the hardware.

The most recent devices are the Tablet PCs and the interactive displays - like the Wacom Cintiq - that have a monitor the designers can draw on with a special pen. These seem to be the ultimate input devices, since the feeling is immediate and the feedback is very similar to that of the pen and paper.

3D Models

One of the key factors for the reduction of the development times and costs is to cut the number of physical prototypes, that require very high investments. In order to do that, managers have to take decisions when the car is still "on paper".

A static image rendered in Alias ImageStudio

While the technical decisions are taken with the help of virtual prototyping, the style of the car is evaluated with digital presentations, that can be static (bidimensional photorealistic images), dynamic (movie clips) or interactive, with the virtual reality tools.

In order to create this kind of presentations a detailed digital model is required.

This model contains different data: the mathematical definitions of the geometries, the material information (textures and other parameters), the scene environment: camera position and target, illumination, groundplane, background, etc.

A screenshot from Alias ImageStudio software: on the right, the material editor.	An image rendered in real-time in Alias Studioviewer

From this information it is possible to create a digital rendering, i.e. a photorealistic image that simulates the real physical interaction between the objects and the environment: lights, shadows, reflections, refractions, etc.

A real-time image preview (lower view) and the final
rendered output (upper view) - Alias ImageStudio

These images can be calculated in a static way, by using specific algorithms like Ray-Tracing or Global Illumination, or in real-time, by taking advantage of the CPU and graphic cards speed, using for example the OpenGL standard.

The static images require longer processing times, but can offer a very high quality and can be inserted in real environments by means of a photo editing process that creates a virtual photograph of the car.

It is also possible to mount a series of renderings to create an animated movie clip, using techniques very similar to those of Special Effects productions in cinema.

On the other hand, the images generated in real-time can be used for interactive presentations, where the zoom and the perspective can be changed at one's pleasure. To handle detailed images, very powerful CPUs and graphic cards are required.

A composition of a digital rendering and a
real environment (Lancia Fulvia Concept)

In the development process there are many different applications for the 3D models: from the concept visualization to the surfaces technical evaluation, to the finite elements analysis for the structural crashworthiness of the body.

Each of them requires a specific 3D model; it's not possible to use a 'universal' model, since the amount of information would be too large to be handled: for example it would be useless for a 3D model used for rendering purposes to contain data about the inner panels, the different sheet thicknesses or the physical properties of the materials.

Another interesting field of application of the digital technologies in car design is the virtual reality, where the inteaction between the user and the computer generated output goes a step further.