Re: [talk-au] Well I bought an L1/L5 Mouse GPS
The device is quite amazing. Will use 30-40 satellites from a mix of GPS, GLONASS, BEIDOU, QZSS (only on Windows, not on Android) and GALILEO. Is getting signals from both L1 (1575MHz) and L5 (1176MHz) bands from most GALILEO and half of BEIDOU and GPS, so removes most of the ionosphere noise. And then the kicker is, if I capture the raw measurements I can then run it against corrections from Geoscience Australia and get 10-30cm accuracy, so they say. In a session this afternoon I walk around objects of interest and form a star on survey marks. I also walked around a sporting pitch circle to apply the circle test, that is travel in a circle and then the largest inner and smallest outer circle that encompasses all points indicates the accuracy. Looking about 17.5m inner and 19m outer for a soccer centre circle. So I’m convinced. From: Bob Cameron Date: Thursday, 23 June 2022 at 7:11 pm One of the cross checks I do is to use a bidirectional Mapillary track layer. I'd suggest fairly good for road centering in open places (ie no phase delay GPS reflections). No good for non ___ Talk-au mailing list Talk-au@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-au
Re: [talk-au] Well I bought an L1/L5 Mouse GPS
One of the cross checks I do is to use a bidirectional Mapillary track layer. I'd suggest fairly good for road centering in open places (ie no phase delay GPS reflections). No good for non covered cross street positioning of course. Bob On 23/6/22 11:45, Alex Sims wrote: Hi, I’ve now got a relatively (<$100 + postage) Mouse GPS. It is amazingly accurate. That’s the good news. Now I can see a whole bunch of streets, buildings etc out by 1-5 meters as **some** features were traced without correcting the image offset. Also found my cheap GPS and an OSX machine are not a great combination. GPSD gets confused and ends up with mojibake most times. Virtual serial port is fine in screen, QGIS etc. Still fun Alex ___ Talk-au mailing list Talk-au@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-au___ Talk-au mailing list Talk-au@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-au
Re: [talk-au] Well I bought an L1/L5 Mouse GPS
On 23/6/22 11:45, Alex Sims wrote: Hi, I’ve now got a relatively (<$100 + postage) Mouse GPS. It is amazingly accurate. That’s the good news. Now I can see a whole bunch of streets, buildings etc out by 1-5 meters as **some** features were traced without correcting the image offset. Also found my cheap GPS and an OSX machine are not a great combination. GPSD gets confused and ends up with mojibake most times. Virtual serial port is fine in screen, QGIS etc. Still fun Alex An error of 1-5 meters ... that would be 'acceptable' at least for most. I take it you have the GPS antenna in the centre of the street when you state the error, trust you don't get run over? If your doing this by car then you need to travel in both directions and take the middle of the two traces. Having gathered GPS tracks to and from work over some weeks they do vary quite considerably with some 'outliers' so you need to be very careful if you only have one trace. Statistically to reduce the uncertainty at least 6 measurements should be taken, that would be 6 in one direction and 6 in the other direction... The newer GPS stuff uses more than one constellation of satellites .. and that has improved the accuracy. ___ Talk-au mailing list Talk-au@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-au
Re: [talk-au] Well I bought an L1/L5 Mouse GPS
Again, a recommendation to deal with imagery offset "smears:" start with the "street network" (grid, whatever) first. That "lays down the meridians" as accurately as you know with minimal effort right down to the centerlines of multiple-lane tarmac. The small (er) stuff like buildings, those follow "later." Otherwise, you are pretty much chasing your tail. ___ Talk-au mailing list Talk-au@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-au
Re: [talk-au] Well I bought an L1/L5 Mouse GPS
On Jun 22, 2022, at 6:45 PM, Alex Sims wrote: > I’ve now got a relatively (<$100 + postage) Mouse GPS. It is amazingly > accurate. That’s the good news. > > Now I can see a whole bunch of streets, buildings etc out by 1-5 meters as > *some* features were traced without correcting the image offset. Also found > my cheap GPS and an OSX machine are not a great combination. GPSD gets > confused and ends up with mojibake most times. Virtual serial port is fine in > screen, QGIS etc. > > Still fun I don't know the specific product, I'll look it up (and I'm in the States, maybe I can't get one, or only with difficulty, not worth shipping / taxes / duty / customs, whatever). Image offset-derived "smears" in OSM's data can be a pain in the neck, especially as you get "multiple drifts" from a number of (imaging) sources. However, 1 to 5 meters, today (2022) isn't terrible. And over years (yeah, sorry for those in a hurry), I have noticed "this gets better." It's an ongoing effort. Think of it like a slow motion countdown to zero, but like Zeno's Paradox, never really quite gets there. Too, precision can be in the eye of the beholder. 1 to 5 meters? Hey, you're not lost, perhaps a bit "smeary" but not lost. JOSM does have a way to "imagery offset" differing layers, though I find it's only a temporary solution and try to keep these at 0,0. My recommendation is to not try to do too much correcting all at once. Chip away at it. The data do get better. Slowly, surely. ___ Talk-au mailing list Talk-au@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-au
[talk-au] Well I bought an L1/L5 Mouse GPS
Hi, I’ve now got a relatively (<$100 + postage) Mouse GPS. It is amazingly accurate. That’s the good news. Now I can see a whole bunch of streets, buildings etc out by 1-5 meters as *some* features were traced without correcting the image offset. Also found my cheap GPS and an OSX machine are not a great combination. GPSD gets confused and ends up with mojibake most times. Virtual serial port is fine in screen, QGIS etc. Still fun Alex ___ Talk-au mailing list Talk-au@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-au
