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Dual freq GPS and map alignment

Posted by kucai on 29 July 2018 in English.

With the introduction of dual freq chip from Broadcom, and the maturing firmware on Mi 8, the possibility of 30cm accuracy becomes much closer to mappers (hopefully standalone receivers are in development too). How are you guys planning to deal with this? Do you think there will there be a map alignment wars? Will iD incorporate that imagery offset db plugin like in JOSM? Do we go nuts with different imagery having different lens zoom ratio on the same zoom layer and having align both to a unified offset?

The OCD in me wants to align everything precisely, but I sure appreciate the Soviet’s approach of “good enough”.

Discussion

Comment from Warin61 on 29 July 2018 at 06:07

Think you’ll find 30 cm accuracy is after averaging .. say 24 hours?

Even if you can get 30 cm, there will have to be 2 traces with the same vehicle going in different directions to get an average for the road center.

Then .. who needs that accuracy? Someone plotting their property boundaries maybe. But for normal people who can look up and see what is there, meters either way is good enough.

Comment from philippec on 29 July 2018 at 07:29

OK, they are not normal people, but the blind might be interested. Google Developer Documentation thinks that great things are going to happen the next years. Also by using the raw GNSS data and the new WIFI.

We should not miss the boat.

So all my drinking water fountains will have to be revisited. The discussion will be what to map. The faucet or the button ? The UNO will have to intervene.

I am practicing on geodetic points. Does anyone know how to enter the Belgian Lambert Coordinates in JOSM ?

https://play.google.com/store/apps/details?id=com.stgrdev.gpssatellitesviewer does not have the Lambert 2008 CRS.

Comment from Warin61 on 29 July 2018 at 07:45

The blind have been navigating without GPS for many years.

Some bubblers don’t have buttons. Ideally you map both actuator (and its method of use) and outlet together with there heights.. will also need data for steps..

The datum used by OSM may have to change… things re going over to a different system. So times will change.

Comment from Tomas Straupis on 29 July 2018 at 10:02

The problem is that osmers got used to low quality imagery like the one from mikrosoft. Imagery should be fixed, not workarounds found. In some countries official precise imagery is available for vectorisation, so gps traces are only required for forest (invisible) routes, where gps would not get 30cm accuracy because of forest obstruction to gps signal. Also on the side of steep hills and mountains you would get consistant incorrect position of gps.

Comment from kucai on 30 July 2018 at 04:56

Warin, I believe that the latest version of the firmware gets that 30cm in much less time than that, although high accuracy is not reliably available every single time. I prefer processed stationary gps points (from nmea logger) on a visible landmark instead of gps tracks since that seems to be a better measure of accuracy. Looking forward to what this new development in gps positioning can do to make OSM/mapping better.

Comment from Piskvor on 30 July 2018 at 09:24

Even if you do manage to capture a trace with 0.3m precision, and align it with a similarly precise map (!), what next? Other map users will still come by casually, with a zoom level where a precision <5m is indistinguishable, even if in 5 years the majority of their chipsets would give them a <2m precision.

In other words, going from ~5m to <1m accuracy might be useful eventually, but requires cooperation all across the stack, not just at the surveying end - and the returns are diminishing rapidly at this scale. In my opinion, getting a collision (“edit war”) between two micromappers will still take some years.

Comment from aharvey on 31 July 2018 at 14:19

Eventually you’ll run into the issues at https://blog.openstreetmap.org/2017/03/31/osm-plate-tectonics/

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