Astro Boy made of what?

I came across this wall art in Shinjuku the other day. It depicts Astro Boy, a Japanese old style manga character. What impressed me was not what was depicted on the art work but how it was drawn. It was made of old subway tickets. According to the description by the picture, the number of the tickets used in the work comes to 138,000! Hundreds of volunteer people arranged the tickets after the original picture was scanned, converted to dots and split into thousands of sheets using a computer program. I don't know it can be called "art" but it was really impressive.