In North America, on piste alpine skiing is classified by a
where trails are graded by difficulty. Novice, intermediate,
and expert trails are denoted by a green square, a blue circle,
and a black diamond, respectively. Each mountain has a specific
composition of green, blue, and black trails. For example,
is composed of 16% ,
and 25% .
In the ternary diagram
below, the trail composition of 2028 ski mountains across North America are depicted using a
barycentric coordinate system.
The number of mountains in each hexagonal bin is encoded by color intensity and
the predominant trail difficulty is represented by color hue. For example,
a light blue bin indicates that there are only a few mountains in the bin and that the
predominate trail composition of the bin is intermediate. Hovering over a bin with the
mouse reveals the individual mountains comprising the bin.
Silverton and Mount Bohemia are both composed of dificult terrain; however,
they differ greatly in elevation change. With all other things being equal, a mountain with
longer runs is more difficult. The small multiple
below illustrates elevation change from resort base to peak of five
different representative mountains including Silverton and Bohemia. The extent of elevation
change in North America is bounded by
Mulligan's Hollow in Michigan at only 130 feet and
Revelstoke Mountain in British Columbia
at almost a mile of vertical elevation change.
To compact the dynamic range, the vertical axis encodes the square root of elevation change
while the area of each bubble chart
denotes the number of trails at each resort. Each inner node depicts one trail and the color
represents trail difficulty. The number of inner nodes cooresponds to the number of trails at
has the most difficult ski terrain in North America. The ternary plot illustrates its extreme
difficulty while the small mulitple highlights its large vertical elevation change.
Silverton is the only mountain with 100% expert terrain and it has over 3 orders of magnitude
more elevation change than the next most difficulty resort—Mount Bohemia. Together, these features make
Silverton the most difficult ski resort in North America. Ski it if you can!
Additional details about the design and implemenation of this project can be found
in this blog post.