What is Rendering?

Something magical happens when the rendering process takes place in a design project.

Rendering is a technically complex aspect of 3D production, and here at D Cube Design we think it’s fascinating to delve deeper into the common techniques and history of how it has come about.

So, we have put together this Q and A to answer some of the questions that we are most commonly asked:

What is rendering exactly?

The term ‘rendering’ refers to the calculations performed by a 3D software package’s render engine to translate the scene from a mathematical approximation to a finalized 2D image.

During the process, the entire scene’s spatial, textural, and lighting information are combined to determine the colour value of each pixel in the flattened image.

The process is similar to developing a film into photos, the Photographer must develop negatives and print photos before they can be displayed. Computer graphics professionals are tasked with a similar necessity.

When an Artist is working on a 3D scene, the models are manipulated with a mathematical representation of points and surfaces (more specifically, vertices and polygons) in three-dimensional space.

When did the word first start appearing in the design world?

The earliest use of the word was back in 1970 when “scanline rendering” came into existence. In the 1970’s rendering became a more distinct subject with the increasing sophistication of computer graphics.

What are the different types of renders? How do they differ?

There are two major types of rendering, their chief difference being the speed at which images are computed and finalized.

Real-Time Rendering:

Most prominently used in gaming and interactive graphics, where images must be computed from 3D information at an incredibly rapid pace.

• Interactivity: Because it is impossible to predict exactly how a player will interact with the
  game environment, images must be rendered in “real-time” as the action unfolds.
• Speed Matters: In order for motion to appear fluid, a minimum of 18 – 20 frames per second must be rendered to the screen. Anything less than this and action will appear choppy.
• The methods: Real-time rendering is drastically improved by dedicated graphics hardware (GPUs), and by pre-compiling as much information as possible. A great deal of a game environment’s lighting information is pre-computed and “baked” directly into the environment’s texture files to improve render speed.

Offline or Pre-Rendering:

Used in situations where speed is less of an issue, with calculations typically performed using multi-core CPUs rather than dedicated graphics hardware.

• Predictability: Offline rendering is seen most frequently in animation and effects work where visual complexity and photorealism are held to a much higher standard. Since there is no unpredictability as to what will appear in each frame, large studios have been known to dedicate up to 90 hours render time to individual frames.
• Photorealism: Because offline rendering occurs within an open-ended time-frame, higher levels of photorealism can be achieved than with real-time rendering. Characters, environments, and their associated textures and lights are typically allowed higher polygon counts, and 4k (or higher) resolution texture files.
• Varied output types:

1. Photo-realistic – This is where the image is as close to a real photograph as possible.
2. Water-colour – The final output of the render is in a water colour painting style.
3. Gel Shading – The colour and shading are solid rather than shaded. This is commonly used for cartoon style renders, for example this Cel Shading.

What does it look like when a Designer is making a render?

We’ve found this great You Tube video that explains this really well…

What software do you create renders with?

Although rendering relies on incredibly sophisticated calculations, today’s software provides easy to understand parameters that make it so an Artist never needs to deal with the underlying mathematics.

A render engine is included with every major 3D software suite, and most of them include material and lighting packages that make it possible to achieve stunning levels of photorealism.

The two most common render engines:

Mental Ray – Packaged with Autodesk Maya. Mental Ray is incredibly versatile, relatively fast, and probably the most competent renderer for character images that need subsurface scattering. Mental ray uses a combination of raytracing and “global illumination” (radiosity).

V-Ray – You typically see V-Ray used in conjunction with 3DS Max—together the pair are absolutely unrivalled for architectural visualisation and environment rendering. Chief advantages of VRay over its competitor are its lighting tools and extensive materials library for arch-viz.

What are the three main rendering techniques?

Scanline rendering is used when speed is a necessity, which makes it the technique of choice for real-time rendering and interactive graphics. Instead of rendering an image pixel-by-pixel, scanline renderers compute on a polygon by polygon basis. Scanline techniques used in conjunction with precomputed (baked) lighting can achieve speeds of 60 frames per second or better on a high-end graphics card.

In raytracing, for every pixel in the scene, one (or more) ray(s) of light are traced from the camera to the nearest 3D object. The light ray is then passed through a set number of “bounces”, which can include reflection or refraction depending on the materials in the 3D scene. The color of each pixel is computed algorithmically based on the light ray’s interaction with objects in its traced path. Raytracing is capable of greater photorealism than scanline but is exponentially slower.

Radiosity: Unlike raytracing, radiosity is calculated independent of the camera, and is surface oriented rather than pixel-by-pixel. The primary function of radiosity is to more accurately simulate surface colour by accounting for indirect illumination (bounced diffuse light). Radiosity is typically characterized by soft graduated shadows and colour bleeding, where light from brightly coloured objects “bleeds” onto nearby surfaces.

In practice, radiosity and raytracing are often used in conjunction with one another, using the advantages of each system to achieve impressive levels of photorealism.

So there we have it, a whirlwind lesson in rendering; what it is, the different types of rendering, how to make a render and different techniques that can be applied.

If you’d like to find out more about how our photorealistic CGI services can help your business, please call the D Cube Design team today on 01509 27 61 61 or email us on enquiries@dcubedesign.co.uk