# Mapping Images in Parisian metro stations

One particular aspect of some Parisian metro stations is that stations' walls are curved, even in the sides where one would place advertising posters. Here is a picture of one such station:

I was told that the posters must be mapped to the surface of the walls in such a manner that they appear undeformed to a person standing on the opposite platform. ( My opinion is that they don't actually bother doing this, or maybe the mapping is so subtle that I can't notice it.)

Say the station's ceiling follows a half ellipse centered at $(0,0)$, with major (horizontal) axis $a$ and minor (vertical) axis $b$. And the posters start a position 0 vertically and never exceed a vertical position c (therefore $c<b$). What would such map look like ? And how to properly transform the image in Mathematica given that map. Here is an image to play with the mapping, a woman alone laughing at a salad,

This is what advertising looks like, right ?

One should be able to do this with ImageTransformation, and the map might be simpler than I imagine, and not an elliptic integral. As a side (optional) question, Can you make a dynamic demonstration of this effect, with Graphics3D ? ohh and can you think of an image that would look almost unrecognizable once mapped ?

• mathematica.stackexchange.com/q/26268/5478
– Kuba
May 15, 2015 at 15:33
• @Kuba Yeah Looks like the same question just for a different surface. Should I delete it ? May 15, 2015 at 15:53
• it is a nice question, I would leave it. Maybe just close it and leave the links. May 15, 2015 at 17:11
• Why are women always laughing when they salad? thehairpin.com/2011/01/women-laughing-alone-with-salad May 15, 2015 at 18:04