Magellan OS maps

Adrian Godwin said:

The Magellan topo maps discussed here a month or so ago
have finally been released : I got my copy this morning.
I'm too much of a newbie (both to the software and to
hillwalking) to give an honest review, but I can at least
try to answer questions.

A few points :

<snip>

Quoted message said:

Contours seem to be at 50' intervals on the PC and vary
with the zoom level on the GPS screen. At maximum zoom,
I've found them at 16' intervals but that might vary with
the slope.

Gargggggh! They are showing contours in feet when they were
surveyed in metres. Remember the mess we had when the OS
interpolated metric contours from imperial ones?
--
Phil Cook looking north over the park to the
"Westminster Gasworks"
95/284 5/219 c.100/300 (>900m with drop>100m )

Adrian Godwin said:

The Magellan topo maps discussed here a month or so ago
have finally been released :

Thanks for the update.

Quoted message said:

Contours seem to be at 50' intervals on the PC and vary
with the zoom level on the GPS screen. At maximum zoom,
I've found them at 16' intervals but that might vary with
the slope.

Aren't you just getting confused by setting the wrong
measurement system?

OS maps are measured in metric, imperial is an antiquated
thing. If you set your GPS to metric I suspect you'll find
that the 50' intervals are really 15m (pretty stupid huh?)
and the 16' intervals are 5m. Confirmation would be nice.
Pretty please... :-)

Quoted message said:

The PC software only seems to show a latitude/longitude
grid. I can't find a way to display an OS grid or use OS
references when setting waypoints etc.

That seems pretty stupid too. Are you sure about that?

Paul
--
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Phil Cook said:

Quoted message said:

Contours seem to be at 50' intervals on the PC and vary
with the zoom level on the GPS screen. At maximum zoom,
I've found them at 16' intervals but that might vary with
the slope.

Gargggggh! They are showing contours in feet when they
were surveyed in metres. Remember the mess we had when the
OS interpolated metric contours from imperial ones?

If I set the display units to metric, I get 10m contours on
the PC and 4m on the receiver, in the same area (Ivinghoe
Beacon) at maximum zoom.

-adrian

Paul Saunders said:

Quoted message said:

Contours seem to be at 50' intervals on the PC and vary
with the zoom level on the GPS screen. At maximum zoom,
I've found them at 16' intervals but that might vary with
the slope.

Aren't you just getting confused by setting the wrong
measurement system?

OS maps are measured in metric, imperial is an antiquated
thing. If you set your GPS to metric I suspect you'll find
that the 50' intervals are really 15m (pretty stupid huh?)
and the 16' intervals are 5m. Confirmation would be nice.
Pretty please... :-)

I'm easily confused. However, note that the magellan format
doesn't use vectors for elevation data : it uses a
compressed bitmap. This gives the ability to generate
elevation profiles and a choice of contour intervals (zoom
related, imperial or metric) at the expense of fixed
horizontal resolution. The vectors that Garmin use can give
a result closer to the OS maps, but only if they're willing
to use the space required to plot the lines with a
sufficiently large number of points - the straight line
segments used to plot streets would be very poor.

The Magellan software seems to show 100' or 50m major
intervals with 20' or 10m minor intervals (i.e. unlabelled
contours) on the PC.

The GPS shows similar labelling at the last-but-one zoom
level (about 250ft per cm on the display) but at the 100ft
level it goes a bit odd - a region that had thick lines
marked at 600' and 700' changes to 660' and 720', still
with 5 spaces between them. Placing the cursor on the
lines (difficult to get exact readings) gives 660, 671,
681, 689, 698, 708 foot readings. Yes, it appears that the
720' label doesn't apply to the adjacent thick line but to
the next thin line. Very odd .. I think this is where I
incorrectly got 16' from, as I was misled by the contours
and divided 80' by 5.

When set to metric units, the same region works like the PC
at the 80m/cm zoom level, but at 35m/cm (max zoom) it has
20m major contours and the unlabelled contours are 5 times
denser, working correctly at 4m. So maybe the database works
in metres and there are some rounding errors at the limit of
resolution.

Quoted message said:

Quoted message said:

The PC software only seems to show a latitude/longitude
grid. I can't find a way to display an OS grid or use OS
references when setting waypoints etc.

That seems pretty stupid too. Are you sure about that?

No, but I haven't found any setting to change it. I'm
disappointed - the rep on the stand claimed it would print
an OS grid on the map. However, you wouldn't want to use
this software as a replacement for Anquet - the maps contain
a lot less detail than an OS raster. They're similar to GPS
street maps with the addition of contours, fairly detailed
waterways (right down to drainage ditches) and footpaths.
There are also feature names for major hills, though these
don't always seem to coincide with the summit. Suggest a
region and I'll do a sample screendump.

I think it's really the standard PC mapping software
designed primarily for selecting map regions and displaying
tracks - it's nowhere near as flexible as something like
Oziexplorer. Even the features added for topo maps, like
elevation profiles, seem only partially supported : they
work well on the display screen but there appears to be no
way to print them out as part of a map.

Of course, the GPS still works in OSGB units as normal but
it would be much better if you could enter waypoints and
jump to map locations with a grid reference.

-adrian