Google Earth and KML - Part Two (GETECH)

In the previous post I introduced the topic of working with geographic data in the KML format. As mentioned there, KML is the native data format used by Google Earth (GE) and it is widely supported by both GPS devices and software. I won't attempt to cover all the gory details of working with and editing KML in this series of posts (resource links at the end), but there a few practical things I've learned about working with GPS data in the KML format that I want to share.

As a basis for this discussion I'm looking at two GPS tracks I recorded on a short Kayak trip on the Kayaderosseras Creek near Saratoga Springs. One was recorded using my trusty Garmin GPS and the other was recorded using the GPS receiver in my camera; a Canon Sx260. I'll discuss and compare the accuracy of the two tracks and touch on some other issues you might encounter while using GPS to collect geo-referenced data for use in your projects.

The first issue is evident in the screen shot below (Image 1). The red line represents the track captured by the GPS receiver in the camera. The purple line shows the route recorded by the Garmin. The obvious difference is that the purple line extends beyond the point where the red line stops. That's because the red line stops at the place where I put the kayak into the creek and later took it out (at the Spa State Park Canoe Launch Site on Driscoll Road). I paddled upstream for a mile or so and then floated back down. I had both GPS units turned on and both units recorded the path. The purple line continues because when I got back to the launch point I forgot to turn off the Garmin GPS. So it recorded a track for the short carry from the creek up to the parking area and for my drive home. That data is not useful so the first thing I want to do is remove it.

Image 1: Screen capture from Google Earth. The two lines (red and purple) are GPS tracks recorded simultaneously on Kayak trip on the Kayaderosseras Creek near Saratoga Springs (NY)

I could do that by editing the track directly in Google Earth. That would be easy but it would be extremely tedious. There are several mouse clicks required to delete a point and there are a lot of points to get rid of to clean up this problem. You can see this in image two. For this screen capture I turned off the display of the track recorded by the camera (the red line) and selected the purple track for editing This makes visible the points recorded by the GPS. Each recorded point is represented by a red dot in the image and as you can see, there are a lot of points in just this short section of the route from the creek to my house. To remove this part of the track by editing it in GE you'd click on each points, select Delete, confirm the deletion and repeat. Lots of repeats.

Image 2: Screen capture from Google Earth. With the display of the track recorded by the camera (the red line) off, the track represented by the purple line was selected for editing. This allows us to see the individual points recorded by the GPS receiver. 

A better alternative is to open the KML file containing the track in a text editor and remove the unwanted points from the file. Once you have the hang of it you can edit the data in the file very quickly. There are few steps involved in this process which goes something like this:

1. Export the track to a file. In Google Earth right click on the item in the Places pane, select Save Place As. Be sure to select KML from the format drop down so the file is saved in the KML format.
2. Open the file in a text editor or an XML editor (I use Notepad++; a free and open source editor that is popular with programmers). You may need to configure your editor to recognize that the KML file is an XML file. That should allow the editor display the contents with nice formatting.
3. In this case, removing the points I don't want comes down to removing all the points where the latitude is greater than the latitude of the put-in point. I'm in the northern hemisphere --so the latitude coordinates increase as you go north-- and all the points I want to keep are south of the put-in. Image three shows the map zoomed in on that location with the properties dialog for the point displayed. The properties dialog shows the latitude and longitude of the marker (and the location). This is how I got the latitude I will use as the basis for my edits; any point with a latitude greater than 43.034293 can be removed from the file. A potential complication is that that the coordinates in the KML file are stored using the decimal degree format. That's as you see it in the dialog seen in image three, but that representation is not the default for coordinates in Google Earth. The default is to represent coordinates in the Degree/Minute/Second format; like this: 43°02'03.4548" You can change the representation used by Google Earth using the Options dialog on the Tools menu.

Image 3: Screen capture from Google Earth. Viewing the properties of a marker added at the location of the start/end point of the trip. The properties dialog shows the coordinates of that point.

Once you have a KML file containing your track, and you have a way to identify the point(s) to remove (in this case, latitude > 43.034293) you can remove the unwanted points from the file. To do this you do need to know a little bit about the XML data format and how to edit data stored in XML, but there are many introductions to XML available on-line and I've included references at the end of this post. Also, if you've done any work with HTML this will all look familiar. XML data elements are placed inside of tag pairs and you must delete the entire tag pair or you wil break the formatting of the file (and GE will complain when you try to reload it). You'll also need to recognize how the coordinates are represented. An example from my file looks like this:

<gx:coord>-73.79277999999999 43.034036 102.52</gx:coord>

The coordinate of the location is represented by three values with a space placed between each value (it might be hard to see the space; -73.79277999999999<space>43.034036<space>102.52). The values are:

-73.79277999999999	longitude	a "west" longitude represented as a negative number
43.034336	latitude	a "north" latitude represented as a positive number
102.52	elevation	meters above sea level

As discussed in the previous section, I want to delete any point where the latitude is greater than 43.034293, so this point can be removed from the file. The points are stored in the file in order, so once you find the place break between what you want and what you want to remove you can select all the bad rows and remove them. If editing data in this way is familiar to you then this should get you started. If this is entirely new then you may need more help. Look at the references or ask a friend who knows about this stuff.

With unwanted data removed from your file there is one final step; opening the file in Google Earth so you can see the results of your work. In Google Earth select "Open" from the File menu and find your edited file on disk. If you get warnings about errors check the file over for mis-matched tag pairs. That's it, you can save the file in your Places folder so that Google Earth reopens it automatically or you can reopen the file when you need it in the future.

This post is already rather long so I'm going to cover the other topics I raised at the start in a separate "part two" posting.

Geyser Creek to the Kaydeross

Most visitors to Saratoga Spa State Park experience Geyser Creek by strolling to see the impressive travertine deposits along its' banks or as the lovely stream that flows through the Geyser Creek picnic area. Fed by deep springs, the creek's waters are cool and attractive on even the hottest summer days. From the picnic area a trail follows the stream to the bridge that carries the park East West Road over the creek. At that point Geyser Creek is 20 feet wide and it typically carries a good flow of water. Downstream from the bridge you can see that the the creek flows into a swampy area, but there is no hint that within a quarter of a mile the stream will have all but vanished into that swamp. Water does flow out the other side, but that flow is in the form of seeps and trickles that add to the Kaydeross at various points. Some maps show Geyser Creek as a continuous line from the bridge to the Kaydeross, but don't believe them. There is no single, reliable, channel.

For much of the year bushwhacking into this area is a daunting prospect. Two small ridges punctuate the marsh but most of the area between the Park East West road (on the north) and Northline Road (on the south) is relentlessly wet, muddy, overgrown and buggy. During times of high water it's an impassable quagmire. The few people who visit the area mostly do so from the Kaydeross Creek. I've written previously about floating this stretch of the Kaydeross and a determined explorer could leave the creek at any number of points. As the crow flies it's just over two miles from the Canoe Launch at Gray's Crossing (Northline Road) to the launch site on Driscoll Road. The creek, however, takes four miles to cover that distance and the elevation differential is less than 20 feet. This is a flat landscape.

But there is one time of year when it is possible to enter the area on foot. In the dead of winter you can readily cross the frozen muck and mire to get a closer look at the topography and forests if not the impressive variety of flora and fauna seen during the warm weather months. Figure One shows a scene looking across the Kaydeross during the blizzard of Feb. 8, 2015. It was snowing hard.

Figure One: The banks of the Kaydeross during the blizzard of Feb. 8, 2015. Snow was falling at a rate of 2 inches per hour adding to the already deep snow pack. 

Lest you think I'm being overly dramatic talking about the conditions as a "blizzard'. You can judge for yourself from this short video. Watch the video in full screen to get the full effect.

Figure two shows my route. The snow pack was deep and airy so I left the parking near the Rte 50 Park entrance with my show shoes on. I first followed the Wetlands Overlook trail and then an abandoned road to reach the closed (and capped) Park Landfill. From there another abandoned Park road leads southwest into the forest. After a short distance I left the old road (on the left) bearing south and downhill to the edge of the swamp. I followed a route I had worked out ahead of time across the marshes and a small ridge to the Kaydeross. This route was selected to allow me to stay on State land though it's a somewhat arbitrary point in the winter. The trip covered only three miles for the round trip but with the deep snow and harsh conditions it seemed further.

Figure Two: Route from Rte. 50 parking to the Kaydeross
Map Image from Google Earth

Figure Three was made from the Ecological Communities map in the Saratoga Spa State Park Master Plan. The map legend is shown separately in Figure Four. This map also shows the outline of the State Owned lands and my route is represented by the prominent red line.

Figure Three: Ecological Communities - Saratoga Spa State Park south of the park East West Road. The red line shows my route.
Map Image captured from the Park Master Plan

Figure Four: Ecological Communities Map Legend
Image captured from the Park Master Plan

The Ecological Communities map shows the area to be a matrix of wetland community types with forest and successional fields mixed in. This is a rich ecological mix with the oxbow lakes and vernal pools being especially noteworthy. A vernal pool is an area that is reliably wet each spring but also completely dry for at least part of the year. That means no fish will be present and no fish makes vernal pools an attractive breading habitat for amphibians. Two vernal pools are shown on the map but there are certainly more. One reason that wetland complexes like this are so interesting is that the conditions are highly variable and the lines between community types are constantly being redrawn.

The weather on this day was harsh so most birds and beasts were keeping a low profile, I did see White-Tail Deer and common winter birds; Crows, Juncos, Blue Jays, a Hairy Woodpecker and a Pileated Woodpecker. In warmer weather this area is particularly rich in bird life and it is a designated Bird Conservation area. This is as good a place for bird watching as can be found in northeastern New York.

And my destination for this hike was not selected at random. I knew that the remnants of an old dam can be seen about half way between Grey's Crossing and Driscoll Road. You can find the location in the maps above because my route ends there. But the distinctive 90 degree change of direction taken by the Kaydeross at that point makes it easy to spot on any map. The broken down spillway creates a rapids and, even in this very cold winter, that's enough to maintain a small area of open water (Figure Five). As I approached the edge of the creek two White-Tails dashed into the woods. The ice around the open water was covered with deer tracks and we might surmise that they come here to drink.

Figure Five shows the spot but the flat light and deep snow make it difficult to see the outline of the former structure. I wonder when the dam was in use and its' purpose. I have not found much in the way of specific information about the dam or this area in general. If you know more, or have sources for this information, please leave a comment.

Figure Five: Open water below the old dam on the Kaydeross.

A Busy Summer of Hikes and Water Trips - Kayaderosseras Creek and Cedar River Flow

One of the worst things you can do with a blog is to allow months to go by without posting anything new. That, unfortunately, is exactly what I've done. It's not that I've lost interest in the projects described in earlier posts. It's that summers are short in this neck of the woods and I've been getting out a lot. Many of those outings have been related to the project (at least that's what I tell myself) but some have been just for fun. This leaves less time for writing then I have in the winter (winter is coming!). But setting this aside, I'll return with a a recap of a couple of recent outings.

For starters I purchased a small kayak. Elle and I have a canoe but it's a two person boat and I often end up going solo. It's an inexpensive kayak -a Perception Sport- great for noodling around. I've been out on Cedar River Flow, the Hudson River and the Kayaderosseras Creek. It's not a boat I'd use for whitewater or on a big lake if the wind was blowing but it's great for low-key day trips.

A point worth noting is the need to clean your boat before moving it among different bodies of water. My first outings in the kayak were on the Kayaderosseras Creek -a lowland creek in Saratoga County. I then put the boat on the Cedar River Flow in the central Adirondacks. To prevent the inadvertent spread of aquatic invasive species I cleaned the kayak thoroughly between those outings. New York State now requires that boats be cleaned before entry into many bodies of water and the State has created an enforcement and education program. You can learn more about it here. Take this seriously. There are several aquatic invasives that, once they gain a foothold, cause immense damage and are nearly impossible to get rid. Keeping them out is the only real solution.

A family of Common Mergansers on the Kayaderosseras Creek near Grey's Crossing (early July 2014). Severe bank erosion is common along the lower Kayaderosseras. Also common are invasive plants such as Japanese Knotweed. A local group --Friends of the Kayaderosseras-- are attempting to control the spread of Knotweed. A couple of methods have been tried but Knotweed is really really hard to kill. A recent post to the group's website details plans to simply cut the Knotweed down repeatedly until its' root energy stores are exhausted (or they are).

Issues aside, the Kayaderosseras from Grey's Crossing to Saratoga Lake has a surprisingly wild feel. Bird life is abundant and at appropriate water levels it's a fun, easy, paddle.  

The Driscoll Road launch site. The water level pictured here is ideal for a relaxed float downstream with enough flow that you don't have to get out and pull through shallow sections. Care is needed during wet weather. The Kayaderossas drains a large watershed and it can rise quickly to levels that are much less relaxed. For several miles below Grey's Crossing the route pass through Saratoga Spa State Park (on one or both sides). The site pictured here is an official launch site on state land with Parking on Driscoll Road. This site requires some effort to get down to the water and a carry of a couple of hundred yards from the parking lot but otherwise this is a good put in or take out point.  

Japanese Knotweed (Fallopia japonica) on the bank of the Kayaderosseras Creek.  

Cedar River Flow

Cedar River Flow is large lake formed by a dam on the Cedar River. The main body of the flow is over three miles long with numerous  bays and extensive wild marshes. Boats with motors are allowed but the launch is suitable only for boats you can carry or wheel to the water by hand (limiting the size of both the boats and their motors). Mostly it's a canoe and kayak paradise. The far end (the south end) of the Flow features extensive marshes where the Cedar River flow into the lake. You can paddle up the Cedar River for several miles (or many miles for the more determined) and the hardest part is finding the actual river channel through the marsh.

In late June (2014) I watched two Osprey pull fish out of the lake. Osprey are pretty common in the Adirondacks and when you see them they are a large and impressive bird. On this day a Bald Eagle flew in to check out the fishing and I was able to see the Osprey and the Eagle in flight within a couple of hundred yards of each other. From this I learned from that Bald Eagles are really big birds. The Eagle's wingspan is only a little larger than an Osprey but the Eagle is a much larger and heavier bird. In general, Cedar River Flow is a great place to view Adirondack birds. Along with the Osprey and the Eagle there were Loons, Waxwings, an American Bittern, Great Blue Herons, Canada Geese (nesting), Turkey's (on the road in) and many other common birds.

An absolutely gorgeous day. Late June 2014.

Beaver Dam on Payne Brook. A second source of inflow into Cedar River Flow

At the upper end of the lake I navigated up a narrow channel thinking it was the Cedar River. It was a dead end but worth the trip anyway.

The view from a well used (and probably illegal) camping spot that sits on a small knoll above the Cedar River.  

Leanto on the Cedar River. About 1.5 miles upstream from where the river flows into the lake. 

The river past the leanto leads deeper into the Moose River Plains. The "plains" are a glacial out wash zone characterized by sandy soils and relatively raw glacial features. The Cedar River has a mostly sandy bottom and it cuts through small ridges where only a foot or two of top soil overlay extensive deposits of sand and gravel.