Issue link: https://read.dmtmag.com/i/43993
Trails Co-op Interface When users first arrive at the Trails Co-op Web site, they're given a screen with multiple options. The Viewer tab opens the Google Earth layout to view and examine trails (see Figure 1). The Search tab provides a forum in which users can search for a trail by several options. The New tab allows users to upload trails from GPS units or draw trails. When viewing the Google Earth interface, users can lFigure 2. A chart indicates the distribution of federal trail sources. zoom into a location, pan around and view areas of interest. Users also can click on a trail icon to get more information as well as trail options, including download- ing, commenting and sharing (see Figures 3 and 4). Trails Co-op includes basic map tools such as draw- data from the database, such as a trail name when a user clicks on a trail. Client-side functions include drawing, clearing the map and other basic site func- tionalities such as popup alerts and map resizing. Going Public Trails Co-op serves data to the public in two direct formats: Keyhole Markup Language (KML) and/or GPS exchange (GPX) format. KML files can be viewed in Google Earth or other software that reads KML, while GPX files can be used in many mapping applications and are easily transferred to GPS units. Users can search for a trail of interest, download the trail to a desired format and use the data for whatever purpose desired. An additional layer of trail points was included in the database to help users get a better idea of trail distribution at smaller scales, and each trail's centroid was used to create the location of each point. Creating points allows for a better map-viewing experience, as the number of visible points changes when users nar- row the bounding box to an area of interest. At the smallest scale enabling point display, man- aging jurisdictions such as Forest, National Park and National Wildlife Areas are symbolized using their logos. As users zoom in, trail points appear, indicat- ing each trail's managed use, such as biking, hiking, climbing or motor vehicle. The logos are based on an attribute containing an HTML link to the icon. Each trail was assigned to one of five random colors to distinguish routes from one another. Because it would be difficult for users to see the map interface if all trails were displayed at once, trails are displayed at certain map zoom levels, and only on a user request by searching the database or clicking on a trail point. Because of its open-specification and XML-based formatting, integrating Trails Co-op with Google Earth makes it easy to extract data from the MySQL data- base and display them on a map. Trail styles also are easily manipulated for Google Earth display. 28 GEO W ORLD / SEPTEMBE R 2O11 lFigure 3. An example shows a single trail within the Trails Co-op map viewer. ing, zooming, panning, searching and getting informa- tion. Drawing requires users to place a point on a map, and it's done through JavaScript on the client side. As users click on a map, a point is placed along with a line that connects points. When done, users can enter the drawing into the database as a new trail, giving it a name and/or comments. The trail then is stored in the database in the same format as other trails. To make submitting individual trails easier, an option was added to upload GPX files. Upon successfully uploading the file to the server, a script is run, trans- forming the submitted data to a usable format. The script parses waypoints, routes and tracks of the GPX file, and returns them to the client's map. From there, users can submit the trail to the database in much the same fashion as the drawing option. Web Mapping