Every 3D animated film, video game and product visualisation starts as an empty virtual space. Inside it, an artist builds objects out of thousands of flat polygons, wraps them in painted images, places lights and a camera, and then asks the computer to work out what that camera would see. That last step, rendering, can take minutes or hours for a single frame, and an animation needs 24 or more frames for every second. Understanding where the time goes, and what it costs in electricity, is part of planning any 3D project. Canada has a strong history here: Chris Landreth's 3D short 'Ryan', produced with the National Film Board, won the Academy Award for animated short in 2005.
Polygons and meshes
A 3D model is a mesh: a surface made of vertices (points in 3D space, each with x, y and z coordinates), edges joining pairs of vertices, and faces, the flat polygons the edges enclose. Faces are usually quads (four-sided) while modelling, because they divide and deform cleanly, and are converted to triangles for rendering, since three points always lie on one flat plane. More polygons mean smoother curves but slower rendering, so games use low-poly models with detail painted on, while film uses high-poly models or subdivision surfaces that smooth a simple cage into a dense curve at render time.
| Technique | How it works | Good for |
|---|---|---|
| Box modelling | Start from a cube and extrude, cut and move faces | Hard objects, furniture, simple characters |
| Extrusion | Pull a flat shape out along a direction to give it depth | Logos and text in 3D, architecture |
| Lathe / revolve | Spin a side profile around an axis | Anything round: bottles, vases, chess pieces |
| Digital sculpting | Push and pull a very dense mesh like clay | Organic detail such as faces, creatures, wrinkles |
UVs and textures
A model's shape is only half the picture; the colour and surface detail come from textures, which are flat 2D images. To wrap a flat image around a 3D shape, each vertex needs a matching position on the image. Those 2D coordinates are called U and V (because X, Y and Z are already taken), and producing them is UV unwrapping: cutting the mesh along seams and flattening it, like peeling an orange or unfolding a cardboard box. Seams are hidden where the viewer will not look, and the pieces are laid out so the texture is not stretched: a checkerboard test pattern makes stretching obvious, because the squares turn into rectangles.
| Texture map | What it controls |
|---|---|
| Colour (albedo / diffuse) | The base colour of the surface, with no lighting baked in |
| Normal or bump | Fake fine bumps and dents that catch light, without adding polygons |
| Roughness | How blurry or sharp reflections are: polished metal versus rubber |
| Metallic | Whether the surface behaves like metal or not |
| Alpha / opacity | Which parts are transparent, such as the gaps in a leaf or a chain-link fence |
Virtual cameras and lights
A virtual camera has a focal length, an aspect ratio and an optional depth of field, and every rule of real cinematography (shot sizes, the rule of thirds, camera moves) applies to it. Lights come in a few types: point lights shine in all directions like a bare bulb, spot lights shine in a cone, directional (sun) lights send parallel rays from far away, and area lights emit from a surface and give soft shadows. A 3D scene is usually lit with three-point lighting, plus global illumination: the renderer traces light bouncing between surfaces, which is why a red wall casts a faint red glow onto a white floor. That realism is also what makes rendering slow.
Rendering and render time
Rendering calculates the colour of every pixel in every frame. Games use rasterization, which projects the triangles onto the screen very quickly and fakes many lighting effects, so it can produce 60 or more frames per second. Film and product work use ray tracing or path tracing, which follow rays of light from the camera into the scene and around it. It is physically accurate but slow, and it produces grainy noise unless many samples are taken per pixel. Studios split the job across a render farm, many computers each rendering different frames at the same time. Pixar's Toy Story (1995), the first fully computer-animated feature film, was rendered on a farm of more than a hundred computers.
The energy cost of rendering
A computer rendering at full load might draw 300 to 500 watts, and it may run for days. Energy is power multiplied by time, so a long render uses real electricity, and a render farm of hundreds of machines also needs cooling. Ontario's electricity mostly comes from nuclear and hydro, so each kilowatt-hour produces less carbon than in provinces that burn more fossil fuels, but energy still costs money and every kilowatt-hour has some environmental impact. The cheapest savings come from planning: render small, low-sample tests until the shot is approved, use a denoiser instead of very high sample counts, and re-render only the frames that changed.