Slope illusion 15

Outdoor tilt illusion where an ascending slope appears to descend or a descending slope appear to ascend

e.g. Magnetic Hill in Canada; Wikipedia

since September 13, 2014


Roller Coaster Road in Biei, Hokkaido, Japan

September 18, 2013, reported by Akiyoshi Kitaoka and Seiichi Tsuinashi, supported by a JSPS kaken-hi grant and R-GIRO


The nearer slope (south slope) is a descent of 4.4º (7.7%) and the farther one (north slope) is an ascent of 6.0º (10.5%). The latter appears to be steeper than it is.

Copyright Akiyoshi Kitaoka 2013 (September 18)



When viewed from the opposite side, the illusion is not so manifest for the south slope.



When viewed from the bottom, the sonth slope appears to be steeper than that when viewed from the top of the north slope.




(north slope)

The upper left field appears to be a cliff, but


the slope of this field is not so steep.


Road connecting to the Roller Coaster Road





Seiichi's slope illusion pages


Slope illusion 14 (Illusory slopes in Tsunan and Tokamachi, Niigata, Japan)

Slope illusion 13 (Slope-ascending water in Tsunan-twon, Niigata-prefecture, Japan)

Slope illusion 12 (Slope-ascending water in Ujitawara-town, Kyoto-prefecture, Japan)

Slope illusion 11 (Skewed staicase of the Shigaraki Ceramic Cultural Park, Shiga, Japan)

Slope illusion 10 (Skewed staicase of Shomaru railway station, Saitama, Japan)

Slope illusion 9 (Illusory slope in Minamitane-town, Tanegashima-island, Kagoshima, Japan)

Slope illusion 8 (Illusory slope in Nakatane-town, Tanegashima-island, Kagoshima, Japan)

Slope illusion 7 (Danjo-zaka and Okyo-zaka in Amakusa-Shimojima, Kumamoto, Japan)

Slope illusion 6 (Slope-ascending river in Miyama, Nantan, Kyoto, Japan)

Slope illusion 5 (Ghost slope in Okagaki, Onga-county, Fukuoka, Japan)

Slope illusion 4 (Slope-ascending water in Tanushimaru, Kurume, Fukuoka, Japan)

Slope illusion 3 (moving-back slope in Hashikami, Aomori, Japan)

Slope illusion 2 (Mysterious slope in Towa, Iwate, Japan)

Slope illusion 1 (Mystery zone in Yashima, Takamatsu, Kagawa, Japan, etc.)


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