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GPX ‘trace’ and related ,matters

Tuesday 29 August
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Richard, when uploading a GPX file to a CT map the first image that appears contains a turquoise line that is the ‘original ‘ GPX route  , as well as CT’s interpretation of that route. When you save that image as your chosen route the turquoise line disappears, as it does if you make any change ie ‘Any’ to ‘Paved’. for example. Is there any way that  that ‘original’ can be retained on the CT route image? A related question is what, on the drop down menu for the various types of map available’ does ‘Trace GPX’ mean? When you select it it just brings up photo/ file options?


John Buswell


Tue 29 Aug, 18:37

Hi John, it's a little difficult to follow so forgive me if I step on your toes.

A gpx Trace is just a layer of the gpx file shown on the map. My understanding is that CT simply displays it on top of the map. It is useful for creating a route from a gpx file or for seeing the variance between a plotted route and what was actually followed. It is very useful but has little importance for actual navigation. I think of it as a clear acetate sheet overlaying a (paper) map. 

A gpx trace has to be specifically selected to be seen on the map. That is done by selecting "Trace GPX" from the map options button and then locating the file on the memory of your device.

Unlike you, I can change the route, change paved to gravel and back again without losing the trace file. However, if I change the map type I will lose the trace. (A quick test suggests that I can simply add the trace back again - I haven't tested for all map types). 

Also, if I save it, the trace disappears. Again, I can add it back later.  

(Using an Android Chromebook and an android phone, both using Chrome)

Importing a gpx is a very different thing. That is creating an actual route using a gpx file. Perhaps this a record of a route already ridden, a copy of someone else's route, or even a route planned on CT. Unlike the trace, it is a real route and can be edited and saved. It is imported from the "Journeys" tab on the "My Profile" Page.

CT may adjust that route on import (as, I think, do most other planners) to better suit the map etc. This is most obvious when there is a lot of places on the original gpx that CT normally wouldn't direct us to.

If you are seeing both the trace (turquoise line) and the imported gpx route I think that's because you have imported the gpx (on your Journeys page) and added the Trace file from your phone or computer. (Or vice versa)

Is there any way that that ‘original’ can be retained on the CT route image?

I'm not sure what you mean by "CT route image"?

With just the trace gpx on the screen you can create a route to match it exactly - I think that's the main purpose of the Trace feature. I've just checked and I can do exactly that, changing surfaces, viapoints etc. 

If you want an actual image (picture) of the map you could just try a screen grab?

A related question is what, on the drop down menu for the various types of map available’ does ‘Trace GPX’ mean? When you select it it just brings up photo/ file options?

I think this might be key. 

That is referring to the Trace I mentioned above - what I think is your "Turquoise line".

 Without knowing how you are doing this (phone - ios or Android, PC (or even the app? etc.) it seems to be a matter of getting familiar with the File Manager software. If you play around you should be able to navigate to the folder where your gpx file is, select it and it will appear as the Trace. If you're seeing the Turquoise line it seems that you have already managed this.

If you have 2 separate routes, for example a planned route and what you actually rode, or a paved version and a gravel version, it is possible to display both on a map (display only, they can only be edited separately). There is a bit more info here:

Wed 30 Aug, 21:41

Thanks Hobbes!

As you say, the cyan/turquoise line isn’t saved with the route, it’s just displayed as assistance when you first load it.

You can display it, or any other .gpx track, at any time by using the ‘Trace GPX’ button. When you click that, your browser will ask you to select a file. Find the .gpx file on your hard drive, and select it. c.t will then show it as the cyan/turquoise line. Again, this is not saved with the route – it’s just a visual aid.

The line shouldn’t disappear when you change from ‘Any’ to ‘Paved’ or similar. It will disappear, however, if you change to Ordnance Survey mapping. This is because OS maps use a different projection (grid system) to everything else, and c.t has to completely reset its map display in order to show them. In theory this is fixable but I haven’t had time yet, I’m afraid – ask me when I’ve finished the Android app!

Thu 31 Aug, 08:46

Thanks Hobbes and Richard for,  as ever , your detailed responses. That has cleared these issues up for me. No fear of ‘toes being stepped on‘ Hobbes, I realised that how I was explaining  the queries might be confusing so  I’m always willing to learn. Cheers