''It's called trompe l'oeil technique, which is a French word for deceiving the eye,'' Mr Keer said yesterday.
''It's an anamorphic painting with a perspective illusion; so you have to stand at a certain point, to get the point of view.''
The 43-year-old, from Utrecht, in the Netherlands, started on the 10m work, Fantasy World of Fibre, at 3pm on Monday.
''I like being on the street. When you work in the studio, you only have two senses to work with. Here, you get the wind, the weather conditions and the people around you. You have more senses you can use,'' he said.
''Also, as an artist, you can never directly answer your own questions; like, is your work good enough? Can it be improved? You always ask yourself these questions as an artist. In the street, these questions get answers,'' he said.
''When I've finished, I'll stand over there and the painting will be in the public domain. And that's fine with me. At the end, I usually have to stand in line with everybody else to take a photo of my own artworks.
''It should last for a couple of weeks, because I painted it in acrylic. But, it depends on the weather and how many people walk over it.''
The artwork was part of a Gigatown social media competition to find the first southern hemisphere town to access a one-gigabit-per-second internet connection and $200,000 development fund.
The artwork would draw attention to Dunedin's bid to win the competition, Digital Office project manager Josh Jenkins said.
''We're stoked to see a visit from Leon. Street art has become more popular in the past few years and having an international artist in Dunedin is an honour.''
The five Gigatown finalists will be announced on September 30 next year.
Wanaka was leading the Gigatown standings yesterday with 503,382 points, ahead of Oamaru, on 294,939 points. Dunedin was in seventh place, with 80,857 points.
The artwork will be unveiled in the Octagon at 3pm today.
For more information on Gigatown, visit gigatown.co.nz
