Effect of Sensor: Magnetic Azimuth Using GPS for direction

[Bob Denny]

While moving in the car and recording a track, I selected "rotate map" (course up not north up) with the azimuth to Magnetic (Sensor settings, Use True North off/unchecked). Traveling true north on a road that runs true north. The whole map and track, along with the course line, rotated to point in the direction of Magnetic north. So I made some tests. With the map set for "rotate map" and Sensor set for Magnetic North, the display looks OK as long as you are going slow enough (slowly walking) to be using the compass for heading. However, when you speed up and Locus shifts over to using the GPS for course ("heading" but not really, right?) the entire display (map, track, guiding line, course projection) rotates away from "course up" by an angle equal to the magnetic deviation (-14 deg here in Arizona USA, so it rotates clockwise 14 deg). I think this is a bug.

[Bob Denny]

This is actually a big issue for me... is there something I need to do with the settings or is it a bug?

[Menion]

Bob, I'll check it tomorrow (I wanted today but due to work on some other stuff, I completely forget)

[Bob Denny]

No rush, I apologize for bugging you.

[Menion]

no apology needed. It's sometimes only way to achieve fix of some problems, so refresh topics where you need answers, no problem

anyway I'm checking it and trying to understand where exactly is problem...

1. may you please install this test version so we have same base? (you may also check new system for settings of right panel ) - https://dl.dropbox.com/u/8015949/Locus% ... .7.4.2.apk

2.in settings > sensor, Use hardware compass - true, Use true bearing - true, Auto change - false

 - in this case, locus will take magnetic bearing from internal compass (and reduce to true bearing if needed, by bearing + declination) and use it

this settings you may simply test at home, so check please if there is any problem in rotation of map etc. You can also change Use true bearing to false and test it also.

3. change Use hardware compass to false.

 - in this case, locus will take true bearing from GPS (and reduce to magnetic bearing if needed, by bearing - declination) and use it

here is needed some movement, so once you'll ride somewhere, please check it. Here you may also check "Use true bearing" - true/false

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I'm testing it at home and simulating and for me, all possible combinations seems to be OK. So unfortunately I need from you more precise description and testing to solve this. Thanks!

[Bob Denny]

Thanks for this. I am totally busy for a couple of days more. I will try this Sunday or Monday.

[Bob Denny]

The APK seems missing, 404 not found. I have Locus Pro 2.7.4. Is that ok for your tests?

[Menion]

ah sorry. I'm usually older test versions removing

here is current one https://dl.dropbox.com/u/8015949/Locus% ... .7.4.5.apk

[Bob Denny]

OK I have done  the test. Click the images for full size screen shots.

The Compass/GPS also showing the magnetic variation here.


The display on North up


Track up - Hardware compass Use true bearing = true


Track up - Hardware compass Use true bearing = false


Track up - GPS heading (hardware compass off to make sure) Use true bearing = true


Track up - GPS heading (hardware compass off to make sure) Use true bearing = false


To me, the "use true bearing" should only affect the displayed bearing values (true or magnetic) and not the orientation of the map itself. When moving, "track up" should be "track up" in all cases. With Use True Bearing = false, as you can see with both the hardware compass and the GPS as the heading source, the track is not up, it is rotated away from "up" by the magnetic variation.

[Menion]

ah damn, this is what I needed to hear whole years "When moving, "track up" should be "track up" in all cases" ... it's clear and simple and I was still overlooking it

fine, so all fixed and tested and should work. In application was little bit mess between values. When you obtain bearing from GPS, it's in "TRUE", from internal hardware compass, it's "MAGNETIC". Computed values are always "TRUE" ... anyway, all seems correct. I would like to release new version in friday if google will communicate with us and fix some market problems, so check it and let me know

[Bob Denny]

Excellent. I write astronomy software for a living (see http://acp.dc3.com/), so I know how it is that something obvious can sit out there for years!! Thank you!!