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Pennsylvania’s Highest Point: Mount Davis

Posted in America, GIS on July 7th, 2010 by Jim – Be the first to comment
Mount Davis Observation Tower

The observation tower at Pennsylvania's highest point, Mount Davis.

On our trip back home from Pittsburgh, we decided that an excellent place to stop would be the highest point in Pennsylvania.  I have never been a highpointer, but after my first state high point adventure, I can easily understand how addictive it can be!

The Mount Davis high point is located on a mountain ridge called Negro Mountain.  It is about 4.37 miles from the Pennsylvania / Maryland border, and just over 16.5 miles from the Pennsylvania / Maryland / West Virginia tripoint. My GPS showed the location to be 39.785841°N, 79.176596°W, with an elevation of 3,362 ft.  Which is much more accurate of an elevation than I normally expect from my GPS.  According to the Wikipedia article on the point, the coordinates are 39.786111°N, 79.175833°W.

Windmill at the Casselman Wind Power Project

My attempt at an artistic photo of a windmill at the Casselman Wind Power Project

We saw a few interesting sites on our way to the High Point.  The first of which was the Casselman Wind Power Project. We decided to get out and explore the wind mill area.  I had never been that close to a wind farm before.  It is a really amazing source of power, and it appears to be located in a fairly suitable location, as most of the turbines were turning.

Mount Davis, Elevation 3214 feet, Highest Point in Pennsylvania

The road sign marking the state's highest point.

We eventually headed back on our journey to the state’s highest point, and headed up the mountain.  The mountain wasn’t very steep at all, and we didn’t even realize we had made it to the top when we passed the high point road sign.
Ken at Baughman Rocks

Ken climbing on Baughman Rocks

There was a small pull off here, so we got out and took some photos.  There was also a trail going into the woods to a site called Baughman rocks.  We headed back to see what the rocks were all about.  They were pretty cool, and were apparently created by the freeze-thaw cycle which creates similar formations on the mountain.
The climate on the mountain top apparently results in stunted tree growth, the land is of little use to agriculture, and the weather can be brutal.  Somerset County, PA (where Mount Davis is located) claims to be one of the snowiest places in the United States, with over 200 inches of snow each year.  This is attributed to its proximity to both lake effect snows coming from Lake Erie, and Nor’easter storms originating over the Atlantic Ocean.
Highest Treetop in Pennsylvania

What I assume is the Highest Treetop in Pennsylvania

Next we packed up our car and headed to the high point observation tower.  It provides excellent views of the surrounding countryside, and you can even see a few small towns.  I really would love to come back up in October to see the leaves changing color, it must be an amazing sight.
One thing that stood out to me in photos of the area before I arrived was a particularly tall Pine Tree.  In the photos, it kind of looked like a Cell Phone tower, but upon closer inspection, it actually is a tree.  I have attached the photo of the westward view from the Observation Tower so you can see for yourself.
Topographic map of the area

Topographic map of the area around Mount David

There is a topographic map on the top of the observation tower that gives you a good idea of how the land is laid around you.  There is a good explanation as to why some of the nearby mountains look taller, and how it is just an optical illusion.  This map also notes where different towns are, and you can easily identify them.
Mount Davis is closer to I-68 than it is to I-76, so we took I-68 back to our rendezvous point in Carlisle, PA.

Sideling Hill Gap

Sideling Hill Gap Road Cut

Interstate 68 also had a treat for us.  Interstate 68 traverses Sideling Hill, just as the Pennsylvania turnpike does.  The Pennsylvania turnpike used to tunnel right though Sideling Hill, and the tunnel and roadway are still open to daring bicyclist.  The Pennsylvania turnpike was widened and the tunnel became a major bottleneck.  The route was originally designed for train traffic, so grades were kept to a minimum.  PennDOT determined it would be cheaper to route the highway through a gap in the mountain than to update the tunnel.  PennDot was very lucky that a sufficient gap was nearby that they could use for the highway.  Highway engineers in Maryland were not so lucky with Interstate 68.
The only gap in Sideling Hill in Maryland is at the Potomac River at the West Virginia / Maryland State line.  The engineers decided to make a large road cut instead, and create an artificial mountain gap.  I became interested in road cuts after reading Roadside Geology of Pennsylvania for a geology course I was taking.  Road cuts show the stone formations underneath the mountains, and give you some insight into how the mountain could have been formed.  Seeing the Sideling Hill road cut was an excellent surprise along our trip!
Appalachian Brewing Company

Appalachian Brewing Company

No trip is complete without a stop at a local brew pub.  We stopped at the Appalachian Brewing Company just outside of Camp Hill, PA for some excellent beer, rosemary bread sticks, salad, and peanut butter pie!  The waitress explained to us that they are not located in the borough of Camp Hill because the borough is a dry town.  That is the first I had ever hear of a Pennsylvania municipality being dry!

I got to learn a lot about Pennsylvania on this trip, and am looking forward to highpointing in NJ and DE in the near future.  I also came across an excellent webpage with highpoints for all of Pennsylvania’s 68 counties.  I hope to get to a few of these this summer!

ESRI Shapefile Shapes and Parts and KML analogies

Posted in GIS, Uncategorized on July 2nd, 2010 by Jim – Be the first to comment

ESRI shapefiles are split up into “Shapes” which are split further into “Parts”.
For example: One could think of a college or corporate campus as a group of buildings.  The individual buildings could be stored as “Parts” and the entire campus could be stored as a group.
KML files work in a similar fashion, although the terminology is different.  In a KML file, the “Shape” is termed “Placemark” and the “Part” is termed by its data type (ie. “Polygon”).
Figure 2.1 – Part: A single building (part) is
highlighted. (osm.org image)
Figure 2.2 – Shape: A entire campus (shape)
or group of buildings is highlighted.
(osm.org image)

Determining if a Polygon is drawn clockwise or counterclockwise

Posted in GIS, Technology on February 10th, 2010 by Jim – Be the first to comment
According to the ESRI Shapefile Documentation,
“The neighborhood to the right of an observer walking along the ring in
vertex order is the inside of the polygon”.  Meaning that all normal or
“clean” polygons are drawn in a clockwise fashion.  When it comes to
holes in the polygons, these are defined by a counterclockwise path
delineating the polygon.
The first step to
determining if a polygon is an additive vector or a subtractive one is
to determine the direction in which the polygon is formed.  ESRI
Shapefiles do not support polygons that cross their own lines, which
makes calculating data with them a bit easier.  One method to determine
the direction the polygon is formed is by using Green’s Theorem.
This method would require one to take the current coordinate (x1,y1),
and the next one (x2,y2), and apply the following formula:
∑(x2-x1)*(y2+y1).  For each line segment, one would then need to add
the result to a running total, and if the number ends up being
positive, the polygon is clockwise, and if it is negative, the polygon
is counterclockwise.
The Formula:

Example:

KML code:

<Placemark>
<name>
Big Triangle</name>
<styleUrl>
#stdstyle</styleUrl>
<Polygon>
<outerBoundaryIs>
<LinearRing>
<coordinates>
-76, 41,0
-75, 40,0
-77, 40,0
-76, 41,0
</coordinates>
</LinearRing>
</outerBoundaryIs>
</Polygon>
</Placemark>

(Screenshot from Google Earth)

(Figure 2.1)

Using the KML code above to create the triangle above:

Line Start Coord End Coord Equation Result
1 -76, 41 -75, 40 ((-75)-(-76))(40+41) 81
2 -75, 40 -77, 40 ((-77)-(-75))(40+40) -160
3 -77, 40 -76, 41 ((-76)-(-77))(41+40) 81
Total: 2



KML code:

<Placemark>
<name>
Small Triangle</name>
<styleUrl>
#stdstyle</styleUrl>
<Polygon>
<outerBoundaryIs>
<LinearRing>
<coordinates>
-76, 40.75,0
-76.5, 40.25,0
-75.5, 40.25,0
-76, 40.75,0

</coordinates>
</LinearRing>
</outerBoundaryIs>
</Polygon>
</Placemark>

(Screenshot from Google Earth)

(Figure 2.2)

Using the KML code above to create the triangle above:

Line Start Coord End Coord Equation Result
1 -76, 40.75 -76.5, 40.25 ((-76.5)-(-76))(40.25+40.75) -40.5
2 -76.5, 40.25 -75.5, 40.25 ((-75.5)-(-76.5))(40.25+40.25) 80.5
3 -75.5, 40.25 -76, 40.75 ((-76)-(-75.5))(40.75+40.25) -40.5



Total: -0.5



There is also a really good flash based demo on how this works available online here: http://www.mechanisms101.com/greens_theorem_demo.html

Philadelphia Bicycle News: Ben Franklin Bridge Extends Hours For Bike Week

Posted in Uncategorized on May 8th, 2009 by jimmyrocks – 3 Comments

So the Ben Franklin Bridge is awesome to bike over.  I did it not too long ago so I could explore Camden.  The people I met over there were all very nice, but I did meet a dog over there that probably was going to kill me.  Luckily its owner was able to restrain the beast from having me for dinner.

In any case, Bike Week (not this Bike Week) is next week, and they’re going to keep the bridge opened until 11pm! Just keep in mind that it’ll be dark, and there are parts of the walkway where you’re really not supposed to bike, and I can only imagine they’ll be more dangerous when you can’t see anything.

Enjoy!

Philadelphia Bicycle News: Ben Franklin Bridge Extends Hours For Bike Week.

Netflix WTF

Posted in Uncategorized on April 9th, 2009 by jimmyrocks – Be the first to comment
Hmmm, Jerry A wonders, Im not sure my disc will get back to them with this.

"Hmmm," Jerry A wonders, "I'm not sure my disc will get back to them with this."

I wonder where 99999-9999 would be.  The highest ZIP Code is 99950 in the extreme southeastern part of Alaska, including the City of Ketchikan, AK. 99999 is reserved for special uses only.  Sorry Netflix.

#No Data (via The Daily WTF)