Hanoks, traditional Korean houses, are beautifully straight and right-angled from a distance, but when you get up close, the columns appear to curve. This is intentionally achieved through optical compensation techniques such as baehleum columns and purim. Hanok is more than just architecture, it’s a work of art, a result of the pursuit of both visual beauty and structural stability.
When we look at a woman with a high waist, we see the beauty of her curves. This comes from the grace and softness of curves, and this aesthetic is found in many places, from natural forms and the human body to man-made structures. However, a body shape that is concave in the center can seem unstable to support the body. The feeling of instability, as if it’s about to wobble, can cause people psychological discomfort, which in turn affects the beauty of the form. Conversely, a straight tree provides structural stability along with the aesthetic appeal of an honest form. This logic also plays an important role in architecture: solid, straight forms provide a sense of stability, which, along with visual beauty, creates trust.
This logic also applies to the architecture of hanok, a traditional Korean house style. A reflection of the Korean philosophy of life, which emphasizes harmony with nature, hanoks are designed to be more than just a place to live, but to exist as part of the natural world. Upright columns and flat roofs are used to support the house’s stability, while also creating the visual beauty of straight lines and right angles. As a result, most Korean hanoks have formal architectural elements, such as rectangular elevations and regularly spaced columns. This isn’t just for outward stability, it’s also a result of the pursuit of natural beauty.
But as you get closer to a hanok, you start to notice something strange. From a distance, hanoks are rectangular in shape, the columns are upright with a certain thickness, and the roof is exactly horizontal, but up close, the houses are crooked or tilted, contrary to what you might expect! Why are Korean hanoks not as upright as you might expect, and why do they look crooked from a distance? The answer is optical illusion. An optical illusion is when we perceive the shape of a picture or object differently than it actually is, and surprisingly, Korean hanoks use this in reverse, intentionally twisting the house or using curved elements to make it appear to stand upright, a process known as optical compensation.
When we look at a hanok, there are several ways that we perceive it as distorted, meaning that there are several optical compensation techniques that make the house appear to be standing upright. The first and most common one is the “draining pillar”. This is an optical illusion correction technique applied to Korean hanoks, and is more familiar to us from the book “The Draining Pillar of Muryangsujeon”. A leaning column is a shape in which the bottom third of the column is the most convex, meaning that the column is not uniformly thick and is convex in the center throughout. This is because a column of constant thickness, when viewed from a distance, creates the optical illusion that the center is concave. Intentionally making the center convex makes the column appear to be of constant thickness, and is also structurally more stable.
Another function of a convex column goes beyond simply correcting an optical illusion, and is to create visual focus. When people look at a hanok, their eyes are naturally drawn to the center of the column, where the curve of the column acts as a stabilizer, creating a sense of balance in the overall architecture. This makes the hanok come across as a “house in harmony” rather than just a “house that stands”.
Perspective is also an important contributor to the optical illusion that the edges of a house appear to be farther apart than they actually are when viewed from the front. For example, a hanok is an exact rectangle when viewed from above, but when viewed from the front, it may have a convex curve in the center, or the columns at the edges may appear to be widely spaced apart, even though they are evenly spaced. A technique used to compensate for this is called purim, in which the center of each corner is concave when viewed from above, so that when a person stands in front of it, the edges appear closer than they actually are. This creates the illusion that the house is flat when viewed from the front, even though it is actually concave in the center.
Another optical illusion is that when you see columns standing in a row, the columns on the edges appear to be open at the top. In a hanok, the columns that support the house are required to be upright for structural reasons. However, just as important as the pillars actually standing upright is the shape of the pillars. To achieve this, the edges of the pillars are tilted slightly inward to give the illusion of standing vertically, known as “ogeum”.
When you look at a hanok from the front, you can see the geometric beauty of the roof eaves forming a horizontal line at right angles to the vertical columns. But there’s an optical illusion here, too. If the eaves of the roof were actually horizontal, the eaves at both ends would appear low and the columns at the edges would appear relatively short, giving the hanok an uncomfortable feeling when viewed from the front. The solution to this is to use ‘joro’, which raises the eaves at each end, and ‘eosung’, which makes the edge pillars taller than the center pillar. This creates a visual horizontal line on the roof that matches the vertical pillars, and also has the effect of widening the view from the inside of the house to the outside.
As you can see, Korean hanoks are more than just aesthetically pleasing; careful consideration has gone into ensuring that all of the elements that make up the house are in harmony with each other. This harmony goes beyond the residential function of the house and has important philosophical implications, symbolizing the balance between nature and man, between architecture and the people who live in it.
This is how Korean hanoks use optical illusions to make the house appear to stand upright when viewed from the front. Of course, the optical illusion is experienced differently by different people, so the appearance of a hanok from the front may vary somewhat from person to person. However, there is one optical illusion that most people don’t realize when looking at a hanok photo or actually seeing a hanok from the front: the drainage pillar. The author of Leaning on the Drainage Pillar of the Muryang Faucet easily looked up the shape of the actual pillar and found that the drainage pillar doesn’t look like a pillar with a consistent thickness. This is due to the unavoidable limitation of hanoks, which require empty space between the columns in order to properly realize the optical illusion. However, in the case of hanoks, since the purpose of the building is residential, there is a wall between the columns, so the optical illusion of the drainage columns cannot be fully realized. If you look at Greek or Roman temples, for example, you can see the empty space between the columns, which is helpful if you want to see the optical illusion of entasis.
If you think about structural stability or the efficiency of the house-building process, it makes sense to build vertically and horizontally, regardless of how it looks. Why did our Korean ancestors go to the trouble of correcting the optical illusion when building hanoks? It’s because they perceived the house as a work of art, not just a place to live. So in addition to satisfying the structural and functional elements of a hanok, they also wanted to embody its visual beauty. They wanted to appreciate the overall appearance of the house when it was finished, and they wanted to embody the beauty of the form without compromising its essential conditions. The emotion we feel when we look at a hanok is likely due to the care our ancestors took when building their homes.
This careful consideration is why hanok is not just architecture, but an artistic expression that seeks to balance nature and human harmony, beauty and function, and still resonates with many people today.
