[OSM-talk] Golf course rendering for OpenStreetMap (mapnik)

[Richard Weait]

On Mon, Aug 17, 2009 at 2:49 PM, Colin McGregor<colin.mc151 at gmail.com> wrote:
> Time for me to play devils advocate here for a moment. I have on rare
> occasions played golf on a par 3 course (I'm not very good...). But
> one of the things I do know is that some course maintainers shift the
> holes from time to time. So while say water hazards stay fairly fixed,
> a hole may shift by several meters  each month...

Hello Barrister to the Devil. ;-)

> So, how does one track hole movement from month to month?

Short answer
One does not.  That is the responsibility of the golfer.

Long answer
Pin placement, that is the location of the flag and hole on the green,
can move every day for tournaments and every day or two depending on
how busy the golf course is.  I've traced the outline of the greens as
best I can.  It would be out of the ordinary for a pin to be placed
outside of the green, though sometimes temporary greens are created
due to weather damage.

I have not, yet addressed pin placement.  I am unlikely to address
exact, daily pin placement at all, as that would likely fail the "map
it if it is nailed down" test for inclusion in OpenStreetMap.

This exact daily pin placement issue is faced by the golf courses as
well.  They have a scorecard with the distance from each tee printed
on it.  When the pin moves, that distance changes, but printing these
things on-demand does not seem to be the way they work.  (At least not
at the courses I've seen.)  There are also yardage markers on or
beside the fairway, usually at 150 yards, and sometimes at 100 and 200
as well.  Some courses print yardage to the green on each sprinkler
head as well.

Each tee box will have a distance marker.  The tee blocks indicate
from where the golfer must hit, and those may be removed a substantial
distance from the nominal marker.  You may see golfers pacing in the
tee box; they are counting the difference from the nominal distance.

Golfers expect the printed pin distance on the scorecard, fairway
marker or sprinkler head, to be to the distance to center of the
green.  Often the flag will give the golfer a clue if the pin is at
the front, middle or back of the green by the colour of the flag, or
by the height of a smaller flag below the main flag.  Other courses
have pin zones on the score cards that tell the golfer where on the
green the pin will be.  Armed with the knowledge of the distance to
the center of the green, and the relative position of the pin on the
green, the golfer can consider wind, temperature, elevation above sea
level, depth of rough, ball lie, and then select the right club.  Then
I shank it into the woods.

Some courses go further than maps and scorecards and supply a guide
book.  These include for each hole, an idealized shot plan, that shows
where a good golfer would land each shot.  Even then, given the
expense of compiling and printing such a guide, the pins and tees are
put in the center of the tee box and green.  The golfer calculates the
difference.

There is a proposal for these ideal shot planners on the wiki but I
have not included those yet.  I would want to do a site survey to
include shot planning for this course.  I've also omitted hole number,
distance, par and rating as they are not apparent from the aerial
imagery.  Well we could make safe guesses for par if pressed.

Best regards,
Richard.