ORS (spire measure): Frequently Asked Questions
- Q: Why does (insert favorite peak here) come out poorly (or get beaten by some other peak)
on your list?
A: Remember that ORS, while roughly correlating with visual impressiveness, is not going to
agree perfectly with everyone's idea of what the "best" peaks are. It certainly does
slight a great many high-elevation peaks, ones with either little local relief or little steepness. If your
favorite peak seems unfairly slighted, think carefully about what its local relief and steepness are,
whether it has a very broad summit (hence lacking a single point with steep relief in all directions),
and (if looking at RORS) whether it lies next to a peak which may fare better in terms of ORS.
A little thought in this direction usually explains
the apparent unfairness.
- Q: But what about (insert particularly pointy/steep peak here)? It seems to be the epitome of spirelikeness,
with lots of steep relief,
but it doesn't appear (or isn't ranked highly).
A: There are some peaks which have some very steep terrain (maybe a steep technical climb to the summit)
but which do not rise as high above the local terrain in general. Often peaks which are in the heart of
a range fall into that category---the Palisades in the Sierra Nevada come to mind, for example.
They are beaten by Mount Tom, which lacks a bit in steepness, but is closer to the edge of the range,
and hence to low terrain. Hence it comes out
well in terms of local relief.
There is a tradeoff involved in setting up ORS, between "slopism" (favoring steepness) and
"heightism" (favoring large relief). ORS makes this tradeoff in a particular way (chosen
for elegance and simplicity), which
will not accord exactly with everyone's personal opinion. In particular, technical climbers tend
to be very slopist (more so than ORS) while hikers tend to be heightist. ORS
works out somewhere between the extremes. If you find yourself not agreeing overall with an ORS list,
it is likely to be because you are significantly more slopist or more heightist than
- Q: But my favorite peak is not even on your list! I admit it won't top Peak X in terms of spire measure,
but it should appear!
A: If the list is ranked by reduced ORS (RORS), or has a RORS-based cutoff, then
the explanation may be that your favorite peak is probably quite close to another peak which is
superior in terms of ORS. RORS then treats your favorite peak
as a subpeak of the superior one, which is liable to greatly reduce its RORS value.
- Q: Why bother with RORS at all? ORS measures what I want (roughly) and it's
complicated enough already.
A: ORS is like height in that it assigns a value to every point on the earth's surface
that varies continuously as you move the point. If we want to make a finite "Top N" list, you cannot
use any measure like that, just as you cannot use pure height to make a list without imposing
some sort of cutoff. RORS is like prominence, in that it only gives high values
to a finite set of points, which can be put in a list. See the
ORS explanation page or the
explanation of prominence on the main peaklist.org site.
- Q: How can I calculate this on my own?
A: There is a feature for calculating (unreduced) ORS built into Edward Earl's Winprom
program. Currently this is the only publicly available implementation of the spire measure
- Q: Why was it called "spire measure" when it measures lots of things other than spires?
A: The name "spire measure" is certainly not perfect, which is why we have changed to using the term "ORS".
However, it is supposed to be suggestive,
not limiting. First, spire measure actually can be applied to any feature on the Earth's surface,
be it a mountain, plateau, cliff, or rock spire. The name comes from the comparisons spire measure
makes: given two peaks or features of roughly "the same size," the one which is more spirelike
(steeper and/or pointier) will get a higher spire measure. However given a small peak with a classic
spire shape and a much larger one which is not particularly steep or pointy, the larger peak can get
the higher spire measure, simply due to its size.
- Q: Are there alternative names for this notion besides "spire measure" and "ORS"?
A: The notion of spire measure originally went under the name "impressiveness," but this was felt to be
inappropriate, as impressiveness is a highly subjective and variable notion. Another suggestion was
"precipicity," due to Mike Cleven, but we felt that this over-emphasized steepness.
See the explanation page for a more thorough treatment of
many of these issues.
Back to the main ORS page
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