"The Nomad" <no...@the.desert.invalid> wrote in message
news:_xnjK.2955810$391.2...@usenetxs.com...
The true north / magnetic north / grid north difference can be a real
hassle.
We use an Android app on our phones/tablets which displays the GPS position
and track on various scales of OS maps (you have to pay for the OS map
data). The old package (Viewranger) has been bought out and replaced by the
new owner's Outdoor Active app. We noticed that all the grid lines on new
maps were a few degrees off vertical, which looked really naff. When we
reported it to Outdoor Active, we got a garbled explanation which
effectively said that they aligned the maps to true north rather than grid
north (though they didn't use anything as technical as that). I can see that
maps that use latitude and longitude lines should be oriented to true north,
but maps which have grid lines drawn on them, as part of the map, need to be
oriented so those lines are perfectly vertical and horizontal, even if this
is mathematically wrong to a lat/long purist.
Despite the explanation of "that's how we do it" (with the implication
"we're not going to fix it"), I see that a few months later an updated
version of the app now orientates OS maps properly.