GPS and Data Types

GPS Devices: There are no shortage of options here. My first GPS was the basic yellow Garmin eTrex which had no map features, just the basics. These days onboard maps as well as the ability to upload maps are pretty much considered to be a standard feature. I have used a Garmin eTrex, a Garmin Vista Cx and currently I use a Garmin Oregon 450. The Oregon has some nice features like being able to up load topographic maps as well as an altimeter and a bunch of other goodies. In addition Garmin also has the Edge series which is a marriage of cycling computer, heart rate monitor and mapping GPS. Smartphones like the Android based phones and the iPhone have internal GPS units as well as some mapping applications that allow you to use them. My personal opinion is that these smartphones are not really trail hardy devices unless you put them in some kind of case and the battery life is poor in comparsion to a dedicated GPS unit. . If I needed to buy a new GPS unit, today this would be the units on my short list.

Maps Types: There are basically three types of maps that you will use. Maps on Your Desktop, Maps in Your GPS, and Printed Maps. In an ideal world one single software package would take care of all of those needs. I have found that unless you are willing to spending a lot of money it is tough to get a product that meets all of those needs easily. My setup is a combination of some of the least expensive options but not completely free.

GPS Data Types: There are tons of formats that are often manufacture specific but there are a handful that are somewhat universal in nature for the basics of GPS and mapping data. The basic GPS data types are Wayppoints, Routes and Tracks. The GPX data format is pretty much considered the universal format.

National Geographic's TOPO! Software

National Geographics TOPO! State Series sofware has some of the best USGS 7.5 degree topographic maps I have used. It is also fairly user-friendly and has the best map print functions of any of the other software in it's class that I have used. It allows you to view, print and export maps at different scales as well as make routes and annotations. For route planning on a topographic map I really like this software, but the printed maps are where it shines. The software will interface with a GPS to import and export waypoints and routes. However I rarely use this feature which is explained below in the workflow section.

It does have a couple of drawbacks. First it does not allow you to upload a freehand route to a GPS as a track. Related to this it does not allow you to export the freehand route as track in a GPX file. Only Waypoints and Routes can be exported. All versions of the software allow you to download a track from a GPS as a freehand route. Additionally, if you have version 4.2.8 or higher you can import a track from a GPX file as a freehand route. The second drawback is that while it is fairly easy to edit waypoints, and tracks in TOPO! there is not undo feature. Goof something up and you can find yourself redoing a lot of work. I mitigate this with lots of file saves and my workflow which I describe below.

NOTE:  Since I first started using TOPO! there have been some free updates provided for the software.  One of those updates requires that old versions of the TOPO files be updated to the new format.   There is a mixture of both formats on my site.  I have been updating to the new formats as I update the trail maps.  I have noticed that the conversion only works if you open up the TOPO program first and then open the data file.  Double clicking on the data file to open the program does not do the conversion properly. I am currently using version 4.5.0.

Google Earth

I would really surpised if you had not heard of or used Google Earth already. It is an exceptional tool for creating and editing tracks and waypoints when using aerial photography. While this will not help you much for forested rides of the Pacific Northwest or Japan, in the often open southwest areas the trails can be picked out with the high resolution imagery of Google Earth. I love using this for researching new places as well as sharing information.  There are a ton of add-ins for Google Earth and it's intrinsic ability save plots/tracks in KML/KMZ formats are extremely helpful.  There are entire website dedicated to using this application so I'll only cover a few items.

One Add-On Feature of paricularly note are the USGS overlays. There are several organizations that have created the ability to display the topographic maps in Google Earth. While these overlays are simply images of the maps vice actual vector map data they will get the job done if you do not have TOPO! Here is the one that I have used on occasion.

Google Earth is a desktop mapping product and while it is available as mobile application on a smartphone, you need to have an internet connection to make it useful out on the trail. Also while it can produce exceptional 3D rendering of your ride with a GPS data overlay, it will not easily produce a quality map for printing.

Garmin Mapsource

Garmin Mapsource is the software that comes with most Garmin GPS units. If you have a GPS from another company there are numerous comparable software packages. Mapsource is the interface I use for uploading and downloading GPS data and maps to and from my GPS unit. Mapsource has a lot of editing features which I often use for "cleaning up" some of my GPS tracks which is often needed in situations like: I had gaps in satellite reception; we were sessioning/farting around in a area; or I rode something that should not me on the site. It is fairly straight forward to use and has the wonderful UNDO feature which is missing from the TOPO! software.

Note on uploading tracks to your GPS: Most modern GPS units have a lot of storage space, but have some limit on the amount of track points that can be in the Active track or log. My first Garmin GPS unit (basic etrex) had a 500 point limit to Saved Tracks. This meant that if you want to upload a GPS track you downloaded from here or anywhere for that matter it will typically need to contain less than 500 points. (See work around below) Mapsource has a filter function that makes this fairly easy knock down the number of points in a track. When you have the GPS data file open in Mapsource, click on the TRACKS tab and find the track you are interested in. Take note of the number of points then click on the track. A dialog box will open up that lists information about the track. There is a FILTER button on the lower right area of the dialog. Click on it and another dialog opens up that give you options for filtering the track. You can play around with the various methods to reduce the number of points in the track. The less points you have the more jagged your track will appear. If you over filter the track, you can simply click on the undo icon in the TRACK PROPERTIES dialog and try again. My current GPS (Oregon 450) has a 10,000 point limit so I am rarely ever concerned about the number track points any more.

500 Point Max Track Upload Workaround: If you have a unit with a low track point limit, Try this work around. If you want to upload a track with greater than 500 points you will need to go into Track Properties Dialog and in the name area change the name of the track to ACTIVE LOG 001. Make sure to use all caps. This will allow it be uploaded with out the limit. For additional tracks you can do 002, 003, etc...  Be aware that when you use this upload method, your live track data as well as the track uploaded are now one track. This can be confusing to some of out on the trail as your active "breadcrumb" and you uploaded data are one in the same.. Have I been here or not? I prefer to just filter now my tracks before uploading.

Maps for Mapsoure

Garmin has USGS topographic maps that you can purchase and load up into the mapsource software and then upload them into your GPS. These are typically stored on a microSD card in the GPS. But why pay such a premium for them when there are lots of free/donation based Mapsource compatiable resources available. Here are some of them:

Uploading Maps Trick: Be aware that when you upload a map to your GPS it stores everything you upload into either internal memory or a microSD card. This data is stored in a folder called Garmin with a file name of GMAPSUPP.IMG. When this upload occurs it erases your old mapset that was loaded. Most of the time it is no big deal, but I like putting the maps in my GPS and forgetting about them. Here is a method to keep multiple mapset on the GPS. First you will need to have a GPS unit that supports USB Mass Storage Mode. Plug the GPS into the computer then do the following your GPS (directions are for most Garmin units). Navigate to Main Menu --> Setup --> Interface. Verify you are connected then select USB Mass Storage. You will now have a screen icon that shows a GPS plugged into a computer. Shortly thereafter you will have a removable disk drive available to view in your computer. (My Computer for the PC folks) Open the drive and the Garmin folder. The current mapset will be named GMAPSUPP.IMG. Reename it to something else like GMAPSUPP-CA.IMG. Exit out of USB Mass Storage Mode. Then upload your new mapset to your GPS. Whenever you want to switch out mapsets all you have to do is get to any computer, go into USB mode and rename the files around to whatever active set you want to use. There is no need to mess with Mapsource and have to deal with reuploading maps later. When done renaming, exit out of USB mode, cycle the GPS power and you are now running on the different mapset. As a point of reference, I currently have CA as my active mapset, but I have AZ, WA, and Japan loaded on the card. The file names are GMAPSUPP.IMG, GMAPSUPP-AZ.IMG, GMAPSUPP-WA.IMG, and GMAPSUPP-JP.IMG.

NOTE: My current GPS (Oregon 450) does not have this issue and awill recognized the different filename that I have above and allow me to switch them on and off.

GPSBabel and GPS Data Workflow

GPSBabel is a powerful freeware/donateware application that converts waypoints, tracks, and routes between numerous GPS receivers and mapping programs. I use this software extensively for getting the data into the various formats that I have availabe for download on the site. This program is also extremely useful for data you download for other sources that needs to be converted into your particular format. It is a fairly simply program to use and the website had some tutorials to help you along. Below is a diagram of the sometimes convoluted workflow involved with the programs I'm using.

The items in gray are the "products" available for download on the site. Notice that the only way "the products" gets finished from its"native" software. Even though GPSBabel can convert directly from TPO to KML, I still open it up and make sure it looks right in Google Earth.

NOTE: As mentioned above, I have dropped support for the TOPO! format.

One thing to also note with GPSBabel is that while it can read and convert TPO files from TOPO! into numerous formats, it can not write into that format. One arrow I did not show on the flow diagram was that GPSBabel can convert to GPX and you could directly import it into TOPO! However one nice feature of Garmin Mapsource is that you can weed out multiple tracks in the file and then export out just the one track that you interesting in importing into TOPO!. When I was working on the Big Laguna Trail Map, it took several rides out there to get to all of the trails. Mapsource allowed me to chop up the various sections of the ride so that I could save just the new stuff as a GPX file and then import that into my ongoing TOPO! project for the Big Laguna Trail Area.

Here is an example in which I used Google Earth and TOPO! together.   In May of 2006, I rode Iron Mountain, but forgot to bring along my GPS.   When I got home I discovered that there was absolutely no trails shown on the USGS maps in TOPO! for Iron Mountain.   However, the entire trail system was easily discernable from the aerial photo of Iron Mountain in Google Earth.   I zoomed in and drew in the trail system in Google Earth.  Once done drawing the trails, I saved them as a KML file, converted it to GPX using GPSBabel and then imported it into TOPO!

Distance Accuracy with long trips with a lot of elevation changes

    When you download GPS data to the TOPO! software or if you freehand draw a route onto the map the mileage reflected by the software does no account for the distance you travel up and down.  It computes and reads the elevation changes, but it does not account for it in the mileage.  That is why your bike computer will always indicate more mileage than you GPS or the TOPO software.  On a fairly flat or a short ride this difference is negligible.  However, as distance and elevation change of a ride increases this difference can become quite large.  To get a more accurate measurement of the mileage shown on the map you have to do a little math.  To the left is the elevation profile for the Black Star Canyon, Main Divide, Silverado Loop ride that has both a lot distance and elevation changes.  In the lower left hand corner is the mileage readout from mile 0 to the mark were the yellow dot is located.  (The yellow dot is all the way to the right at the end of this route).  On the bottom right hand corner is the readout of the + and - elevation changes.    Since this is a loop ride the + and - should be the same and they are real close.
    Now the TOPO map says this is 25.20 miles long.  Oh, I don't think so.  My legs will surely agree with my bike computer that is more like 26.98 miles.  So this is how to compensate for the elevation changes.    Add up both the  + and - elevation changes.  4480 + 4479 = 8959 feet.  Now convert that to miles by dividing it by 5280 (5280 feet per mile) 8959/5280 = 1.70 miles.  Now we can just 1.70 miles to 25.20 miles the the elevation profile is telling us and we have a much more accurate number.   26.90 miles.  Now there is a .08 mile difference between the map and my computer. 

But Bill, this really sucks to go through all that you say!   Well on all my reviews where this effect could be substantial I have already compensated for it on my marks on the maps and TOPO files as well in my trail descriptions.

The Side-Hill Effect

If you have a long route that is predominately on the side of steep hill, your elevation profile for the entire trip can be wildly off.  This is due to the fact that the Global Position System is usually accurate to within 30 feet. The next time you are out on a trail along a steep hillside take look at the difference in elevation 30 feet to your left and right.  It can be substantial.  Now couple this with a GPS that is logging your position every five seconds.   This "acceptable" variance recorded every five seconds can add up to a lot of extra elevation changes.   A good example of this is the elevation profile for the Santa Ana River Trail.  There is maybe 3,000 feet of actual elevation change, but the profile shows nearly 6,000 feet.    I usually point out in the description what the actual elevation change if there is a significant difference between the profile and reality.

Intellectual Property Note

I post my map files on my site to share and assist people in getting out and riding new places. Please do not download these files and then repost them elsewhere passing them off as your own data in either their original format or a converted format.   If you would like to use some of my stuff email me. I'm pretty cool about things but I do not like being  leeched and will get exceptionally irriated if a commerical interest is involved. More Legal Stuff.

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