If you haven't seen the world's cities as mapped by artist-cartographer Sohei Nishino, now's your chance. Nishino's highly detailed 'Dioramas', maps of some of the world's most diverse urban centres, from Tokyo to New York, were first shown in London in 2011 and amazed everyone from critics to children.

His photographic collages were made from memory with thousands of cut-out snapshots taken in all corners and from all angles of the city. Nishino delighted in the textures, shapes and faces he witnessed, from rivers to big skies, markets to nightclubs, posers to zoo animals, views from skyscrapers and minute details.
Nearly four years and tens of thousands of snapshots later, Nishino's second London show features Berlin, New Delhi, Amsterdam, Jerusalem, Rio de Janeiro, Bern and Tokyo (again, on a much grander scale). All the work has been meticulously crafted by Nishino himself. Not only does he walk the cities alone for six weeks at a time, he uses 35mm film and hand-prints up to 4,000 photographs before he begins each collage.
Up to 2.4m by 1.8m in scale, the results are so full of detail, you must be right up close to read them properly - indeed some pieces require a stepladder for proper immersion.
We caught up with Sohei Nishino to find out why these voyages of discovery are so meticulously crafted, and what keeps him interested in the long process...
Wallpaper*: How does the process begin, right from when you decide which city to photograph?
Sohei Nishino: I go to cities I'm interested in. There's no political agenda. I'm only interested in big cities because people are constantly moving in and out, and it's that kind of movement and energy that interests me. It's important not to do too much preparation. I just let myself rely on the experience of walking – it's the accidental, coincidental elements that make it interesting. Then once I'm home I continue the journey of discovery in the darkroom.

W*: If you're taking as many as 10,000 photographs, you must witness all sorts of improbable things? Have you ever spotted something unlikely, like a murder?
 SN: Not that I know of. But I do like the personal moments that unfold when you interact in urban spaces with a camera. In Jerusalem, for example, I saw a security guard, a real tough guy, who posed for me. But when he turned around he stepped in a bucket of paint. That was really funny, and I put it in. There's definitely a diary element to the maps. Actually, when I show them to the public, I feel like I'm showing my naked body.
W*: How has the process changed over the years, and how do you keep yourself interested in it?
SN: I used to concentrate on architecture and landscape. Now I've become more interested in people, and more comfortable photographing them too. At the beginning I walked for two weeks. Now I stay for six, so I have time to talk to people. It's a very different experience. It's never boring because I'm always changing and watching my internal response to the environment.
W*: I noticed in the Red Light District of Amsterdam you chose to blur the shots, though everywhere else is sharp. Was that a stylistic choice?
SN: Actually, I asked some of the girls on display if I could photograph them, but they quoted me an inordinate amount of money. I had no choice - I went away and made a hole in my pocket and hid the camera inside. So, yes, they were blurry. But I often do make stylistic choices like that. In Tokyo's Kabukicho district, for example, I took the pictures at night instead of in daylight because the neon street signs are a really impressive characteristic of the area.
W*: You've said you're not interested in making a map that is practical or useful. Why is that?
SN: Maps are ubiquitous nowadays. We all use Google but we no longer really look at maps. I've always been interested in the 18th-century Japanese cartographer Inō Tadataka. Old maps were more like portraits back then. People read them, had a dialogue with them. They captured diagrammatic characteristics, like mountains or symbols. They were also subjective. Distance, size - these are such personal things when you think about it. All people perceive them differently. You could say I'm obsessed with finding my own inner scale.