Waypoint Averaging on the Colorado

[+Geofellas]

Since it doesn't look like Garmin are providing Waypoint Averaging on the Colorado any time soon (if ever) I have, at the suggestion of Ranger Fox, written a play anywhere Wherigo cartridge that will allow you to do it.

 

Please feel free to test it and provide any comments, bug reports, issues etc.

 

It is available at the Wherigo website

[+Lignumaqua]

What a brilliant idea!

 

I've tried it on the Oregon and it works, but with a minor glitch.

 

I saved the cartridge on exiting the first time, if I now try and run it again I get asked if I want to Resume the Saved Game.

 

Answering 'No' results in no GPS being available in the inventory - just a blank entry. You can work-around this by starting to exit the cartridge and then canceling the exit (using the 'curvy' arrow button) - the GPS then re-appears in the inventory!

 

Answering 'Yes' seems to work correctly.

 

Fantastic concept and a really neat way to add in the functions Garmin forgot...

[+Geofellas]

Answering 'No' results in no GPS being available in the inventory - just a blank entry. You can work-around this by starting to exit the cartridge and then canceling the exit (using the 'curvy' arrow button) - the GPS then re-appears in the inventory!

 

Hmm - can't replicate it on my CO - no idea how to solve that one at the moment.

[+Lignumaqua]

Hmm - can't replicate it on my CO - no idea how to solve that one at the moment.

I seem to have fixed it by saving out another blank game.

 

BTW - can you only have one waypoint at the moment? I've tried saving a number of waypoints with different names and only the last one appears in the list.

 

EDIT: All of them appear in the 'Go to List' but just one appears in the 'Locations' list.

Edited September 15, 2008 by Lignumaqua

[+Geofellas]

I seem to have fixed it by saving out another blank game.

 

 

BTW - can you only have one waypoint at the moment? I've tried saving a number of waypoints with different names and only the last one appears in the list.

 

EDIT: All of them appear in the 'Go to List' but just one appears in the 'Locations' list.

 

Yes - that is intentional as good Wherigo programming practice. The more locations you have active and visible the more work the processor has to do continually checking on them and that could ultimately cause a crash or reduced performance. So I have set it up so that only one can be active and visible at any one time.

 

When you "Go To" one that is not in the "Locations" list it then appears in the Locations list instead of any one that was there previously.

Edited September 15, 2008 by Geofellas

[yogazoo]

Hello,

 

I am wondering about what all is involved in the equation. I know that averaging is the average of coordinates over time but will it give you the estimated error value of the waypoints? Is the GPS "Accuracy" involved in the equation to add a "weight" to the coordinates? Thanks for your reply.

[+Geofellas]

Hello,

 

I am wondering about what all is involved in the equation. I know that averaging is the average of coordinates over time but will it give you the estimated error value of the waypoints? Is the GPS "Accuracy" involved in the equation to add a "weight" to the coordinates? Thanks for your reply.

 

No, as it says on the screen when you run the thing, there is no weighting included in this first implementation. It calculates a simple average of the points collected at 2 second intervals over the time you choose to average for - which I have set to a maximum of 10 minutes (randomly!)

 

The displayed accuracy statistics are intended to give you a subjective sense of how effective the averaging has been.

 

Another measure would be to calculate the standard deviation of the sample set - but most people are not likely to really understand what that number would be telling them anyway.

 

I seriously wonder how beneficial including weighting into the algorithm would be. If there is any prior art available on the subject I would be interested to know - my gut feel is that weighting is not going to significantly affect the final result to any practically useful extent.

 

For placing caches I have to think that a simple average is going to be "good enough"

[+Timpat]

Geofellas, what an absolutely ellegant and brilliant idea! I downloaded your cartridge to my Colorado 300 and it works perfectly! Where Garmin has failed us (so far) you have given us a solution. Awesome work on this!! Thank you!

[+flarbear]

Downloaded it onto my OR 400t and ran it for 5 minutes in my hotel room. With between 5 and 10 meter accuracy it generated a coordinate that Google Maps plots exactly onto the building right on top of my desk, so it looks like it works great!

[yogazoo]

One issue and One suggestion and One comment.

 

Issue: When I go to delete a waypoint the cartridge kicks me out. Repeatable.

 

 

 

Suggestion: Would there be any way to take the "saved" waypoint and bring it up again for another round of averaging? I know Delorme is including this feature in the new PN-40. Say you had a point you want to dial in real good and you want to revisit the sight a few days later to gather even more data under different satellite conditions. Could this be a possibility with the cartridge? I don't know how Wherigo cartridges work but this would be a great asset to have if you really wanted to dial in the coordinates under varying array conditions.

 

Comment: Meters is fine. UTM's are in meters anyway. There is no coordinate system that uses feet. Make us lazy Americans do some math if we really want feet.

 

Thanks again,

 

Yogazoo

Edited September 16, 2008 by yogazoo

[+Geofellas]

Issue: When I go to delete a waypoint the cartridge crashed.

 

Can you send me your log file so I can see if I can replicate the problem. I assume this was on the Colorado?

 

 

Suggestion: Would there be any way to take the "saved" waypoint and bring it up again for another round of averaging? I know Delorme is including this feature in the new PN-40. Say you had a point you want to dial in real good and you want to revisit the sight a few days later under different satellite conditions. Could this be a possibility with the cartridge? I don't know how Wherigo cartridges work but this would be a great asset to have if you really wanted to dial in the coordinates under varying array conditions.

 

Hmm - thanks for the suggestion.

 

Raises a few issues:

 

1) Need to check you are at or close to the saved coordinates or it makes no sense to do it - what should be the allowable margin of error? Current accuracy perhaps?

2) It would require saving some statistics along with the saved waypoint (specifically number of samples taken, and, for the benefit of the user's understanding the likely accuracy of the result, the previous values of min/max accuracy) and neither of these are standard waypoint properties - could probably be done though. Gets even more complicated if a weighted average is used - needs more thought.

 

I'll ponder this one

[+Timpat]

Geofellas, I played some more with your cartridge outdoors today and I can average a waypoint, name it, and it shows up in the Locations. I then exit and say Yes to "would you like to save your game", and it says saving cartridge and exits. All good. Upon resuming the saved game my single waypoint is there.

 

Now, if I go and average a second waypoint (in a new geographic location) and name it I get an error message saying "Unexpected Error Closing Cartridge". I'm fairly new to Wherigo playing so wondered if I am causing the errors? It seems as if I can only average a single waypoint on the saved game. If I choose 'No' vs. 'Resume the saved game' upon starting the cartridge I can average a new waypoint, but have lost the first one. Thanks for building this!

[+twolpert]

1) Need to check you are at or close to the saved coordinates or it makes no sense to do it - what should be the allowable margin of error? Current accuracy perhaps?

I think this would be a bell and whistle, not a necessity. At least for geocaching (placing a cache), the user is standing at a recognizable reference point (the cache). If there is no recognizable reference point (on a lake, for example), coming back to re-check coordinates is kind of useless.

 

If you do decide to impose a limit, I would make it at least twice the current accuracy -- and perhaps more (at least if you are using the EPE reported by the unit as "accuracy"). After all, one of the popular measures of EPE is that "there is a 50% probability that the reported location is within EPE meters of the true location." I don't remember the exact numbers, but if that's the definition of EPE the unit is using, you have to approximately double the EPE to get to the probability up into the 90% range...

 

Edited to add: Looked it up 'cause I just can't leave well enough alone. CEP (circular error probable) is the EPE formula which has a 50% probability rating. If you double the EPE calculated via CEP, you will have something with approximately a 95% probability rating. Of course, we have no idea what EPE formula any given unit uses. But the typical certainty factors are between 50% and 65%.

Edited September 16, 2008 by twolpert

[yogazoo]

 

Raises a few issues:

 

1) Need to check you are at or close to the saved coordinates or it makes no sense to do it - what should be the allowable margin of error? Current accuracy perhaps?

2) It would require saving some statistics along with the saved waypoint (specifically number of samples taken, and, for the benefit of the user's understanding the likely accuracy of the result, the previous values of min/max accuracy) and neither of these are standard waypoint properties - could probably be done though. Gets even more complicated if a weighted average is used - needs more thought.

 

I'll ponder this one

 

I'm not sure about your question # (1) but if I hide a cache or mark an important landmark I would simply return to the site of the cache or landmark to add more data to the coordinates (more averaging). The accuracy in returning to the point would be mute since there is something on the ground telling me where I am. Just think of the accuracy one could achieve if you checked PDOP and returned over several days for some more averaging.

 

(2) Would a "resume" type function work? You could simply return to the site and addmore data continuing where you left off sort of speak. I don't know, just speculation.

 

 

PS: I'll get you that log file ASAP (UPDATE-SENT). I experienced aanother crash right after naming my waypoint twice now (seperate condition. I pretty sure it's what Timpat is experiencing).

Edited September 16, 2008 by yogazoo

[+Geofellas]

 

Raises a few issues:

 

1) Need to check you are at or close to the saved coordinates or it makes no sense to do it - what should be the allowable margin of error? Current accuracy perhaps?

2) It would require saving some statistics along with the saved waypoint (specifically number of samples taken, and, for the benefit of the user's understanding the likely accuracy of the result, the previous values of min/max accuracy) and neither of these are standard waypoint properties - could probably be done though. Gets even more complicated if a weighted average is used - needs more thought.

 

I'll ponder this one

 

I'm not sure about your question # (1) but if I hide a cache or mark an important landmark I would simply return to the site of the cache or landmark to add more data to the coordinates (more averaging). The accuracy in returning to the point would be mute since there is something on the ground telling me where I am. Just think of the accuracy one could achieve if you checked PDOP and returned over several days for some more averaging.

 

(2) Would a "resume" type function work? You could simply return to the site and addmore data continuing where you left off sort of speak. I don't know, just speculation.

 

 

PS: I'll get you that log file ASAP (UPDATE-SENT). I experienced aanother crash right after naming my waypoint twice now (seperate condition. I pretty sure it's what Timpat is experiencing).

 

On 1 the program still should check or you could restart a million miles away and get meaningless results.

 

On 2 - yes - that is what we are talking about - but you still need to keep the old data around.

[+Geofellas]

Geofellas, I played some more with your cartridge outdoors today and I can average a waypoint, name it, and it shows up in the Locations. I then exit and say Yes to "would you like to save your game", and it says saving cartridge and exits. All good. Upon resuming the saved game my single waypoint is there.

 

Now, if I go and average a second waypoint (in a new geographic location) and name it I get an error message saying "Unexpected Error Closing Cartridge". I'm fairly new to Wherigo playing so wondered if I am causing the errors? It seems as if I can only average a single waypoint on the saved game. If I choose 'No' vs. 'Resume the saved game' upon starting the cartridge I can average a new waypoint, but have lost the first one. Thanks for building this!

 

OK - I'll try and see if I can replicate that.

 

If you could send your log file to geofellas@gmail.com that would help

 

Thanks

[+Timpat]

OK - I'll try and see if I can replicate that.

 

If you could send your log file to geofellas@gmail.com that would help

 

Thanks

Just saw your reply, email with log file sent. Thanks.

[+Geofellas]

Looked it up 'cause I just can't leave well enough alone. CEP (circular error probable) is the EPE formula which has a 50% probability rating. If you double the EPE calculated via CEP, you will have something with approximately a 95% probability rating. Of course, we have no idea what EPE formula any given unit uses. But the typical certainty factors are between 50% and 65%.

 

OK - thanks - that helps

 

Might be a while before I do anything though

[+Geofellas]

 

Just saw your reply, email with log file sent. Thanks.

 

Thanks - it looks like your last attempt at averaging was when you didn't have a GPS signal since the accuracy was being reported as 9.9999995620235e+24 m - I'm obviously not handling that situation well

 

Clearly I am going to have to do item number 1 on the "still to do" list (which IS in the description of the cartridge ) - that is to deal with when the accuracy is not acceptable.

 

For now folks, please don't try this when you have no GPS signal

 

It's great to have a group of testers like this - it really helps to eke out the bugs and get a handle on how people use the tool so thanks to all

[yogazoo]

Thank YOU Geofellas! This is a really great thing you've done for us Colorado/Oregon users. We wait in great anticipation of your next release!

[+Ratsneve]

Hello,

 

I am wondering about what all is involved in the equation. I know that averaging is the average of coordinates over time but will it give you the estimated error value of the waypoints? Is the GPS "Accuracy" involved in the equation to add a "weight" to the coordinates? Thanks for your reply.

What if the marker wanders or drifts? If you are averaging it you wouldn't be able to discount the error would you? If you manually made WPs you would see the unusual drift and simply ignore it until it self-corrected or cycle the power and the drift would go away. Of course, if you were using an Oregon and WAAS was noticeably important you might have to wait a half-hour before you got it back if you cycled the power? As you may tell I'm still trying to figure out how important WP Averaging really is with such sensitive receivers.

Edited September 17, 2008 by Ratsneve

[+Geofellas]

 

For now folks, please don't try this when you have no GPS signal

 

Also, thanks to Timpat's testing, I have determined that saving and restoring will likely cause a crash as it doesn't save all needed info about the created waypoints. I seem to have fixed that now and have tested successfully in the Emulator and, at the same time, added code to handle poor accuracy issues. I hope to get this sanity checked in the CO and have version 1.7 released by tomorrow (Wednesday, Eastern North America time)

 

UPDATE; This is now available as mentioned here

Edited September 17, 2008 by Geofellas

[+bluelip]

Since it doesn't look like Garmin are providing Waypoint Averaging on the Colorado any time soon (if ever) I have, at the suggestion of Ranger Fox, written a play anywhere Wherigo cartridge that will allow you to do it.

 

Please feel free to test it and provide any comments, bug reports, issues etc.

 

It is available at the Wherigo website

[+bluelip]

Since it doesn't look like Garmin are providing Waypoint Averaging on the Colorado any time soon (if ever) I have, at the suggestion of Ranger Fox, written a play anywhere Wherigo cartridge that will allow you to do it.

 

Thanks, Geofellas. I've already updated to 2.7 so I'll wait for the next release before trying out your script. I'm glad to see this scripting functionality built in. I think this may be a great compromise between 'dumb' handhelds and having to carry around a laptop along w/ your GPSr if you want added functionality.

 

I've had the CO for less than a week, but the support for LUA has me pumped.

 

I'm looking forward to your next release.

 

Best wishes,

Mike Coles

 

Work

Play

Me

Edited September 28, 2008 by bluelip