Pop quiz…who knows what GPS Selective Availability is? I suspect the clear majority cannot define it.
Prior to May 2000 in the interest of national security, the US Department of Defense purposely introduced an error of about 300 feet to GPS signals. When this degradation was removed, public GPS sales increased as their accuracy improved.
One very popular hobby that took off about this time was Geocaching. Via the website Geocaching.com, one can identify local “treasure” sites, enter the site coordinates into their GPS, navigate to the site and sign the log, and subsequently log their hunt on the website. While living in Philadelphia, this activity was very popular with my children and me. Our team name was “Abe Frohman, Sausage King of Chicago,” and there was rarely a month that went by where we didn’t spend a day finding 5-10 sites.
This blog post isn’t solely about Geocaching, it’s also about leveraging OOTB Web AppBuilder Widgets for a purpose. It will guide one through their addition and use to accept coordinates that the Geocaching website provides, and then leverage Esri methodology (i.e. Collector) for the hunt.
As the initial step, one needs to go to Geocaching.com. To identify local, geocache sites, and conduct a search of the immediate area. As shown in Figure 1 (below), there is a geocache located very near the office, along our daily walking trail.
After clicking on the geocache point (Figure 2), we see the name of the geocache (Shocking #3) and more importantly its coordinates (N 39° 35.466 W 104° 50.312).
It is too easy to just enter the coordinates into a GPS and take the lunchtime walk for the grab. Rather, I thought it would be fun to build a new Web AppBuilder within ArcGIS Online that only contains the necessary OOTB widgets to accomplish our task.
Let’s get started……
We create a new Web AppBuilder from within ArcGIS Online, by choosing the My Content Tab, the “Create” drop-down menu, and then choosing “Using the Web AppBuilder” (Figure 3).
As shown in Figure 4, the initial GUI asks for a title, tag(s), and Summary.
Once we click the “OK” button, our initial App is constructed. We can select from a list of themes, styles, and layouts. My girlfriend says that I was absent the day that style was handed out, so we are going to focus on Widgets. May have to write a future blog post and get her opinion on good color choices and styles.
There are several OOTB Widgets that one can choose from. To see what is available, the user can click a location (Figure 5) and the Choose Widget GUI appears (Figure 6).
Our first desired functionality is to show the location of the geocache(s). Geocaching.com shows the coordinates of geocaches in decimal minutes. It would be nice for our Widget choice to accept a copy of these coordinates and direct pasting with no user modification. As highlighted in Figure 6, we are choosing the Coordinate Conversion Widget even though we really aren’t interested in converting anything.
Once we choose the Coordinate Conversion Widget, we can configure it (Figure 7). First thing we want to do is zoom to 1:1,200, once the coordinate is entered. Second thing we want to do is turn off any conversion by clicking the Show checkbox. Click the OK button when complete.
We now want to configure the Widget to accept the coordinates directly from Geocaching.com. By default, the latitude/longitude is supplied as decimal degrees. For us to copy/paste directly, this must be changed to decimal minutes. To continue configuration, click the “Format Input” button, and change the input to decimal minutes and the location of the “N” and “E” to be in front as shown in Figure 8. When satisfied, click the “Apply” button. At this point, it may be a good idea to also save the Application as well.
Time to test. As planned, we copy the coordinates of the “Shocking #3” geocache and paste them into our configured Widget. Unfortunately, we end up in the Gobi Desert (Figure 9).
To be honest, this stumped me. After a sacrificial concussion from banging my head against the computer screen, I noticed that the default longitude was referenced from East. Since we want a West direction, I put a negative in front of the numeric degrees (Figure 10). We now observe the correct geocache location and one may also notice that the stream goes through the SSP building. Falling Water, Skye?
We now need a background map with a layer configured with feature access. I have created other blog posts which show how to do this (see referenced posts below). This layer needs to be added to the base map and saved.
Once we have our layer in place, we need a new Widget that enables us to edit the layer for future geocaches. Using the same methodology as described above, we now add the Edit Widget. Assuming that our map contains an editable layer (i.e. Geocaching Points), we should see it in our subsequent configuration GUI (Figure 11).
Once we have both Widgets in place, we can then digitize our point at the location of the coordinates (Figure 12).
Now that we have a digitized point, we can leverage Esri’s mobile app Collector to go find the Geocache. We first pull up our map, and we see the Geocache location in respect to our current location (Figure 13). Time to go hunting!
David Blodgett and I took off for the treasure only to be disappointed. The Esri software worked very well, except the geocache was missing. We are confident that we were in the correct place because we cheated and looked at the photographs posted on Geocaching.com.
Anyway…Hopefully someone found this post fun and useful. Also, after almost a quarter century of doing GIS, I have learned that there are always multiple ways of doing the same thing. If anybody else has a better way of using OOTB Esri technology for Geocaching, please comment!