Today I released an exciting tool that will help you further repair your GPS tracks for Strava, Garmin Connect, Training Peaks, etc. Sometimes your GPS will record a spurious point - either in your position or in your heart rate / power / elevation / cadence. This tool gives you the ability to locate and repair any of these single point errors. I started making a video, but let's start with this basic tutorial on how to use the new feature.
The feature is located in the "Add / Remove / Edit Track points" section:
- How to edit individual trackpoints in GPS files.
Once you click the blue button, you will be taken to the next screen. It may take a while to load; I've tested activities with 20,000 points and that loads in about 2 seconds. If you're trying to do more than 400,000 points, the browser might crash (depends on how new your browser/computer is). If that is the case, I suggest repairing files on-at-a-time and then trying to combine them after you repair.
- Wait for the page to finish loading so you can repair your GPS Files.
After the page has loaded, the next step is to find the point you want to edit. In this example, we will do a map edit, so I am going to zoom on the map to a location where the GPS obviously recorded an errant point as shown in the image below:
- The GPS recorded a bogus point. In Strava, you wouldn't be able to remove this point, which is where this tool comes in handy.
Once you click on (or near) the errant point, you get a message that says "Scroll to nearest point in the table". When you click that link, the table will scroll to the data for that bad track point. The row in question will be highlighted in a yellow color for 2 seconds to draw your attention.
- Scrolling to the correct Latitude / Longitude for repair.
The easiest - and probably best way to resolve this is to click the little trash can in the 2nd column. That will remove the point. Don't worry, these GPS devices record enough data that missing one or two points will not have any impact on your final ride. Here is what it looks like if you click the trashcan:
- Easily delete bad GPS info.
If you're worried about losing distance, just be sure to export as FIT and include the correct distance and total ascent.
Alternatively, you can drag the point into the correct position as I'm doing in the screenshot below. One issue with trying to move track points is that your final track may momentarily have a burst of speed followed by a lull in speed. This is because it is surprisingly difficult to place a point in the exact place where you really would have been at that exact moment. Just a few feet too far means that you would have had to go faster to achieve that distance in the given amount of time (remember Distance=Rate times Time from school)?
- Dragging track point to correct error in GPS track.
After you drag the point to the new location, the screen will briefly gray-out while the new point is saved. Make sure not to try and change anything while the screen is grayed out. After the point is saved, the cell that you changed in the table will turn green. Also, there is a list at the very bottom of the page that will show all of the changes you make in a session. The row that you made changes to is click-able to help you easily scroll back to a row if you want to make further changes.
- Saving manually modified changes to Latitude / Longitude
If you want to type in a new value for Latitude / Longitude, you can just click on the cell you want to change:
- Editing Lat / Lon Manually - click on the cell.
At this point, you can type in the corrected coordinates - which might be a little tricky to figure out... or you can click on the map. If there is an open edit box in the Latitude/Longitude field, you will be given the option to "Send these coordinates to open edit field" which will copy the coordinates of where you clicked into that box, and then save it.
- Find coordinates from a map to repair your GPS file for Strava / Garmin
Another reason you may want to use this tool is to correct an errant heart rate or power value. In the example below, the GPS recorded a heart rate of 200. Often a Garmin device will record a heart rate of 255 when there is interference from something like power lines:
- Correcting a 255 Garmin Heart Rate.
Just click on the cell with the bad data, and enter the new corrected value. This applies to elevation, cadence, heart rate, watts. You can also edit distance, temperature, and (carefully) laps - though those last 3 items don't tend to have recording errors like the first four values:
- Correcting Heart Rate spike in a GPS file.
- Finalizing your changes to your GPS File.
At this point, the data table for your uploaded files has been changed. If you finish off the combine, all of your changes will appear in the final output file. If you make a mistake while editing points, and it seems too confusing to try and undo the mistakes, just go back to the parent window and refresh as shown below:
- If you make a mistake while repairing your FIT, GPX or TCX files, just refresh the window.
I have recently added a horizontal graph of your Elevation, Cadence, Heart Rate, and Power to the tool. You can click any point in the horizontal graph, and when you do, the table will scroll to the corresponding point so you can edit it. Notice how the row that is scrolled-to turns yellow for 2 seconds.
- Editing Erroneous Heart Rate, Cadence, Power, or Elevation Data
When you have arrived at the row, you can edit it.
To avoid visual confusion in the graph, you can "turn off" Elevation, Power, Heart Rate, and Cadence one-at-a-time. Just click the title bar as shown in the image below. You will see that Cadence and Heart Rate have been "crossed out". Those aren't showing now, but you can click them again to bring them back.
- Hiding Elevation, Cadence, Heart Rate, or Power for a cleaner graph
If you would like to edit track points after you do an interpolation, there is a trick to doing that:
- How to edit points after an interpolation
Step 2: UNCHECK the "Send to Strava" option.
Step 3: Click the blue "Click here to combine gPS Files using Above Parameters"
Step 4: Ignore this downloaded file.
Step 5: Now, you can click the "Edit Points" Button, and instead of seeing the original points, you will see all of the points, including the interpolated ones.