Garmin Oregon 300

captain_paranoia · Posted: Thu Jan 22, 2009 7:09 pm Post subject:

"I bet it's aligned to WGS84 grid north !"

Possible, but their demo screen shots appear to show the mapping aligned to OSGB grid. Which I'd suggest is kinda sensible...

I'm afraid I have no experience of using the device (and very little in using other handheld GSP devices). But I currently work in the field of satellite navigation (just not with handhelds), and have also worked on JPEG video transmission systems. So my experience is hopefully useful...

captain_paranoia · Posted: Thu Jan 22, 2009 7:22 pm Post subject:

"The whole discoverer image on the SD card containg five different map scales comes to 416,144Mb!"

Does the comma indicate a decimal point, is a thousands separator? i.e. is it 417MB or 416GB?

Because I can't see 416GB fitting on any currently available SD card...

So, I'm going to assume that it's 417MB. Which really isn't very much if it's covering the whole UK at 1:25k (see my figures above). And I'd expect that to be very, very expensive, around £10k. Maybe that's why it's crunched so much, so that it's next to useless for any other purpose...

Sorry to bang on, but does it provide full UK 1:25k coverage?

As for the North Reference selection; try selecting Grid North.

Multimap presents non-OSGB Grid alinged maps, too. I wonder...

Streetmap is OSGB aligned:

captain_paranoia · Posted: Thu Jan 22, 2009 7:23 pm Post subject:

"As for the North Reference selection; try selecting Grid North. "

You need to make sure your unit it set up to use OSGB Grid. But you've probably done that; does it present OSGB grid refs, or Lat/long for position?

Darren · Posted: Thu Jan 22, 2009 7:25 pm Post subject:

eyeQue · Lifetime Member Joined: Aug 27, 2008 Posts: 235

Sorry, typo error - 416,144kb for all that I bought - Pembrokeshire and Brecon National Parks @ 1:25 & 1:50 and the whole of the UK at the three other levels. Cost £120 approx.

As Darren has pointed out the UK is split up into National Parks not the whole UK.
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eyeQue · Lifetime Member Joined: Aug 27, 2008 Posts: 235

philpugh · Posted: Fri Jan 23, 2009 11:09 am Post subject:

Botton · Occasional Visitor Joined: Jan 22, 2009 Posts: 1

Here are some figures.

Garnin GB Discoverer Yorkshire Dales takes 415Mbytes of 1G SD card includes about 683sq miles. CNE 2008 for main central European countries (France & around) when copied to Mapsource to SD card takes 550Mb..

They should not be pushed for memory storage CNE 2008 is on a 4G card.

I have a Colorado I hope that is updated soon.

On Colorado through Setup - Heading - you can chose True, Magnetic, Grid, User. I could not detect any movement of the map ( I was in doors)?

The screen is blurred above 1.2mi & below 120ft with Dales Discoverer maps. Above 2mi it might as well show roads.

I think the most pressing problem is not being able to see the Discoverer map in Mapsource to be able to plan routes & way points to download to Colorado or Oregon.

eyeQue · Lifetime Member Joined: Aug 27, 2008 Posts: 235

captain_paranoia · Posted: Fri Jan 23, 2009 2:41 pm Post subject:

Well, the 'track up' view is interesting; it shows that the unit is re-projecting (well, rotating at least) on the fly.

I was discussing this topic with my colleagues at lunchtime, and we decided that Garmin have, like Multimap, re-projected the data from OSGB to WGS84 grid, so that it aligns with their other global mapping solutions (e.g. road network).

This is a compromise decision, and must mean that Garmin have chosen to project all mapping to WGS84 grid, wherever in the world it is. At first I thought this an unreasonable approach, as it would have been fairly straightforward to re-project any WGS84-based vector mapping data (e.g. road network) to the selected local grid (e.g. OSGB). There's a lot less data to re-project than if you have to re-project the raster mapping images (i.e. it's a feasible task on a little handheld GPS).

Then I realised that you'd have to tie the machine to the local grid used for the mapping. Which you might not want to do.

The raster mapping images can be re-projected off the machine (by Garmin, before distribution); doing this on-the-fly on a handheld GPS would have been pretty taxing of the CPU...

Since the example screenshots on the Garmin website show gridlines apparently aligned perfectly, I suspect that they're synthetic; i.e. they're not real screenshots. It would be interesting to get Garmin to comment on this...

Thanks for the clarifications on data set sizes and 1:25k coverage. 420MB isn't unreasonable for 1:50k UK mapping. Judging by the improvements with the new software, it looks like the problem was with poor re-scaling filters, rather than poor raster images. The updated software images look like they've made considerable improvements. Maybe they'll continue to improve as they learn how to write re-scaling algorithms properly...

captain_paranoia · Posted: Fri Jan 23, 2009 2:46 pm Post subject:

"420MB isn't unreasonable for 1:50k UK mapping"

Oops; need to read posts more carefully... 420MB is for the two NPs at 1:25k and 1:50k. I'd have to think about how much data I'd expect for that. But it doesn't sound unreasonable.

captain_paranoia · Posted: Fri Jan 23, 2009 6:01 pm Post subject:

Had another look at the screenshots on Garmin's websites, and I now notice that the one I looked at in detail just happens to be somewhere where OSGB and WGS84 grid Norths align nicely.

The other images show the re-projection to WGS84.

So I conclude that the images are genuine screen shots.

ps. thanks to the kind person who re-worked my long URLs to nice clicky links; must play with the formatting buttons to get the hang of this forum.

empee · Posted: Sat Jan 31, 2009 8:30 am Post subject:

Hi
Have an Oregon 400 since Christmas and looking to get UK Memory map type coverage onto it. When I chose it I was under the impression that OS were about to release OS maps suitable for it. Been following this thread for some time - much of it too technical for me but from what I can gather there is as yet no reliable UK wide 250,000 scale maps available.
Will this change with the mentioned February update?

eyeQue · Lifetime Member Joined: Aug 27, 2008 Posts: 235

I think you have missed the fact that 'UK wide 250,000 scale maps' are in each card already available.

http://www.maps-warehouse.co.uk/garmin-discoverer-1-25.html

Each card contains :

In your Oregon you have already the TOPO for Europe and more!

In my Oregon I turned off all Maps except Discoverer to produce the screenshots below. I moved out of the Pembrokeshire and Brecon National Parks as I have posted plenty of 25k and 50k screenshots. So outside those two areas get:-

.

Notice from Zoom levels up to .5miles you get normal CityNavigator autorouting maps but at .8miles the Discoverer now 'overlays' the CityNavigator maps until the 1: 1,100,000 GB basemap appears at 5miles.

The Firmware upgrade in February may improve what I already have, v2.85Beta did, but I did not know any new OS maps were due!
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My Zoned Speed Camera Icons, available here.

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