Great Britain Discoverer National Parks 1:25k Lake District-Brecon Beacons-Peak District

**Mordorf** · 2nd February 2011, 12:20 PM

The re upload is now complete and I have edited the original post with the new download link.

**tbzr** · 2nd February 2011, 01:46 PM

Lake District now seems to work for me on oregon. (Thanks)

**Brilliant Trees** · 3rd February 2011, 01:51 AM

Hi Again

Have tried the new version and this still seems to be 1:50K scale on my edge 800.

Am I doing something wrong?

Also zooming below 500ft is very blurry. My Memory Map software on my PDA is able to render maps perfectly down to a much smaller range than this. Is this a problem with the Edge 800 or is the Discoverer map just not great when fully zoomed in?

**fluorescent** · 3rd February 2011, 08:37 AM

The map is blurry because it is a rastermap. To explain the difference between a vectormap and a rastermap:

If you want to draw a line in a vectormap the you "draw" a geometric point from which the line starts and a geometric point where the line ends. And if you enlarge the map the points and the line still remain geometric points and lines which have no width and are always clean points and lines. The size of the mapfile in bits is very small and it does not matter if the map covers 5 meter by 5 meter or 50 kilometer by 50 kilometer. A second line: mapfile is double in bits. A map with say 37 lines is 37 times as big as a map with one line.

If you draw a point in a rastermap you have a raster and you must fill one field of the raster with black colour and all the other fields with white colour. From some distance you see a black point in a white field. To draw a line you must fill many many fields of the raster which give - looked at from some distance - a line. If you get closer you see the "fields" and therefore a rastermap looks blurry if you enlarge it too much. The size of the mapfile in bits increases dramatically if the map covers a bigger area as you need more fields of the raster or if you use a more fine raster. A map with say 37 lines instead of one line is only a little big bigger than a map with one line for only the information "white" is exchanged against the information "black" for the fields of the raster where the lines are.

**Brilliant Trees** · 3rd February 2011, 10:39 PM

Thanks for this explanation fluorescent, I assume from this that Memory Map OS Maps are Vector Maps and the Discoverer is a Raster. I may be being picky but compared with my MM OS maps on the PDA the Edge is poor at rendering the map detail. That said its still better in detail terms than the old Garmin Topo Map.

Does anyone else have a comment on the 1:50K v.s. 1:25K issue I raised, while I'm grateful to the original poster for making this available is appears to be a 1:50K and in that regard no different from the full GB Discoverer.

**Mordorf** · 4th February 2011, 11:41 AM

Originally Posted by Brilliant Trees

Does anyone else have a comment on the 1:50K v.s. 1:25K issue I raised, while I'm grateful to the original poster for making this available is appears to be a 1:50K and in that regard no different from the full GB Discoverer.

On my Oregon 450 I need to zoom into 150yds before I see the 1:25K map level. This seems to be the standard for Garmin GB Discoverer Maps.

Thread: Great Britain Discoverer National Parks 1:25k Lake District-Brecon Beacons-Peak District

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