in: Jagge; Jagge > 2007-04-19;
| # Posted 2007-04-20 02:58:59 | |
| simon: | I'm surprised by this tip, even if I understand the rationale. I have used my FR205 with smart recording since the beginning (2 months) and get good results. Perhaps it depends on the runnability of the terrain too.
On a runnable and open terrain, you run fast and smart recording does not affect your trace since you are faster than the error radius (what's the name?). On a slow and highly covered terrain, you are more often inside the error circle and smart recording makes more correction on your position, distorting it. |
| # Posted 2007-04-20 03:13:14 | |
| BorisGr: | This is very cool read, Jagge, thanks! |
| # Posted 2007-04-20 03:53:28 | |
| Jagge: | Smart recording - well, It's not about the accuracy of the trace. The route itself isn't that intresting. It's the time dimension we are interested in. How did we proceed, did we stop, how many times and how many seconds.
You can get the the route just fine with smart recording, but you'll get 3-8 sec "random" gaps between individual points and there is no way to find out how that time was spent. That's why smart is no good and one second (fixed time interval) is the way to go. To make it more easy to read, slow runners may have to filter every second point away (you may have to write a little software for that). Or use a gps receiver with fixed 2 sec saving interva (the Globalsat device does that, you can give any interval you like). --- In the example I was just trying to show how you can "read" the gps track. If you like to learn something, you must have some sort of idea / framework what you are supposed to do there and what it should look like. Then you compare your route against it and make decessions based on it. Looking at these dots will not do you any better. --- Note, if you regularly check your tracks like this, you might be able to see some patterns, find out typical situations where you loose seconds. You can't say much just by one training, but if you keep doing this, you'll may learn where you get it wrong. --- BTW, we never got chance to see this trainging trough with those athletes, I was too sick to be able to do it back then. I was planning to do it by sending these images and thoughts to them, that's why I had these images done. Normally I don't take any snapshots, I just browse the track with ST. |
| # Posted 2007-04-20 05:19:19 | |
| simon: | Thanks for the explanation and this pattern identification idea, never thought of that. Did you try with CompeGPS to get a color-coded "speed-trace" - it seems it would be a bit easier to spot and evaluate slow/fast speed.
http://docmicka.free.fr/forum/ex2.jpg Another obvious use is time loss estimation (either in case of error or different route choices - it gives a better view than the split). http://docmicka.free.fr/forum/ex1.jpg In hindsight, you can tell whether it's better to stay a little longer on trails for example. Especially it can help to change your mind habits regarding a particular terrain: if you thought you were too slow on a particular micro-choice, check with another one to see if it is really slower or if it is just your mind wandering (in this case, focus on mental preparation and self-confidence :)). Not sure I am very clear. |
| # Posted 2007-04-20 11:00:53 | |
| Jagge: | I like to see that actual points. To get speed right, you usually need to average speed with few points, it isnt as accurate as human eye. Also you can see is it really a stop or a gps error.
Instead I am planning to write a little script for this, it will read gpx and drop every second point if needed, plot them on a empty raster (png/jpg/gif) image, using dot color based on speed, but also colouring every 30 th dot with special color to make it easier to see how far you got during each 30 sec sector. You could check this image as it is with any photo editoir of ovarlay it in ocad with scanned o map (or photo taken with digital camera, so you don't need to travel with a scanner). Overlaying two rasters in ovad is pretty easy and straight forward. |
| # Posted 2007-04-20 13:38:43 | |
| simon: | Great, I like that! And perhaps later an integration with RouteGadget?
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| # Posted 2007-04-20 14:30:51 | |
| Kat: | Thank you for the post, Jagge! This was very helpful. |
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