The Two Senses We Cannot Animate

The two that don't fit down the wire

Animation has exactly two channels. Light arrives at the eye, pressure arrives at the ear, and that is the entire apparatus. Anything a scene appears to contain beyond those two has to be smuggled in.

Smell and touch are the two that cannot be sent. There's no lossy version to fall back on either: you can't make a low-bitrate approximation of the smell of a wet wool coat, because there is no version at all. And yet when people write to us about episodes, those two are what they mention most. Not the light was nice. It smelled like my grandmother's kitchen. I could feel how cold that door handle was.

So the interesting question was never how to animate them. It's what actually happens when somebody reports one.

What a picture can and can't do to a nose

Our working understanding — and this is a workshop, not a laboratory — goes roughly like this.

Smell seems to get stored with a whole situation attached rather than as a labelled item on a list. Most people can recognise hundreds of smells and name almost none of them. Recognition arrives complete, with its room and its weather and its year attached, before any word does.

If that's right, then a smell can't be triggered by accuracy. It can only be triggered by situation. Draw the situation well enough and a viewer who happens to carry that particular association supplies the entire thing themselves, instantly, and then quite reasonably writes to thank us for something we did not do.

No image has ever carried a smell. The most any of them can do is stand beside a door you already had, and leave it open.

This is why the letters are so specific and so wildly unlike each other. One shot of a kitchen has produced "bread," "my grandmother's flat," "a bakery in Lisbon in 2011," and, from one memorable message, "wet dog." We drew none of those. We drew a warm room with something covered on the stove.

The five images that do the most work

After a couple of years of trying, we have ended up with a short list that performs far more reliably than anything else. Not one of them is a smell. All of them are the visible half of a process that makes one.

1. 1

   Steam

   The strongest single tool we have. Steam is evidence of heat meeting air, which is the exact physical event that releases most of the smells anybody likes. It also moves, which keeps it from settling into decoration.

2. 2

   A wet surface beginning to dry

   Not wet, and not dry — the edge between them, where a stone slab is dark in the middle and pale at the rim. This is the one that produces the earth-after-rain letters, and it works with no rain anywhere in the frame.

3. 3

   Soot, and the mark of heat

   A blackened kettle base, a smoke stain above a lamp, the darker ring on a hearth stone. These say a fire has burned here for years, and the nose fills in what a fire smells like without being asked.

4. 4

   Anything with a crust

   Bread most obviously, but also the skin of a roasted vegetable. A crust is a surface that got hot enough to change colour, and the colour change is the only part of it we can draw.

5. 5

   Cloth that has taken on water

   A coat over a chair back with the shoulders darker than the rest. Wool that has been rained on has a smell almost everyone in a cold country knows, and drawing it is two shades of one grey.

The common factor is worth naming, because it is the only rule we trust in this territory: every one of them is a transition. Something is changing state — heating, evaporating, absorbing, cooling. A static object rarely smells of anything in a picture, however beautifully rendered. A pot that came off the heat ninety seconds ago does.

Touch is a distance problem

Touch behaves differently, and it is more tractable, because it has a visible correlate that smell does not have: texture. The surface can simply be drawn. What has to be decided is how close to stand.

Temperature travels on this channel too, and it travels best at a boundary. Hands wrapped around a cup rather than a cup on its own. Condensation on the inside of the glass. A breath that is briefly visible. What gets drawn is always the meeting of two temperatures, because a temperature by itself has no picture.

The line where implication becomes catalogue

Because these tools genuinely work, the standing temptation is to use all of them at once, and the result is worse than a cold frame.

A room with steam, and soot, and bread, and a damp coat, and a wet windowsill is not five times as evocative. It is an inventory. The viewer stops being inside a room and starts being shown one. Our internal note for it is this scene is trying to sell me something, and it comes up more often than any other note we write.

One transition per shot. Two if the second is very quiet. That's the whole discipline, and we break it about twice a year and regret it in the grade. For how the individual surfaces get built before any of this is decided, the lantern maker's workshop is the piece about materials.

Can a sound carry a smell?

It can, and we did not expect that.

A sizzle carries hot fat with startling reliability. A stiff broom on a stone floor carries dust. The hollow rattle of a metal lid produces cooking in general rather than any particular dish. And the strangest one: the wind that arrives four or five minutes ahead of rain, which a surprising number of people describe as smelling like rain is coming.

None of these is louder or more detailed than the sounds around them. Each is simply an event that only happens inside a process, and the process carries the association — the same logic as the pictures, through the other channel.

The part that belongs to the viewer

The honest limit is bigger than the technique, so it belongs at the end rather than in a footnote.

Most of the time none of this fires. The association simply isn't there — you never had a wool coat rained on, nobody in your life baked, the smell of a hearth isn't in you to be found — and the shot lands as a nicely drawn shot and nothing more. That's the ordinary outcome, not the failure case. We have no way to install a memory in anyone, and wouldn't want the ability.

And when it does fire, the good part isn't ours. We supplied a wet stone with a drying edge. The kitchen, the year, the person standing in it were already in the room, waiting, and a real wet stone would have done it just as well. All we do is put one in front of you on an evening when there isn't one outside.

Which is a smaller claim than it sounds, and it is the true one. Two of the five senses don't come down the wire. What comes down the wire is an invitation, and everything worth having on the far side of it was yours the whole time.

The evening is warm here.