Ordnance Survey High Definition maps

[Lyle Brotherton]

OS (Ordnance Survey) have just released their latest versions (updates) for their 1:25 000 Explorer and 1:50 000 Landranger map series in in HD (High Definition) format. When these maps first appeared I trialed them and although the detail was significantly improved on my PC’s screen, when I printed them the colours were much bolder than on the standard definition maps and masked some of the finer details on the maps.

I have just tested this latest update release and am pleased to say that OS have resolved the colour issue… The printed maps are far superior, being 660 DPI (dots per inch) in HD resolution and 254 DPI with the standard. (660x660 = 435600 and 254 x 254 = 64516 which means that HD has 6.75 more definition)


Personally for use on either my PC screen or Android device I would stick to the standard, however for printed maps they are a serious consideration, especially if you are instructing a group or navigating in an area of danger.

[captain paranoia]

That's quite an improvement.

I seem to recall that the 1:50k tiles were served at a lower resolution (even allowing for the different scale) than 1:25k, but I can't find my notes on the subject at the moment...  That might just have been the GetAMap interface, though.

> (660x660 = 435600 and 254 x 254 = 64516 which means that HD has 6.75 more definition)

But it still only has an linear resolution improvement of 660/254 = 2.6.  It's the linear resolution that is important in such imagery, and it is the linear resolution that will always be quoted for satellite (or other imaging).  For instance, I'm currently analysing some imagery that is originally 0.6m resolution (although it's been transformed into an angular projection for the end application).

[Lyle Brotherton]

Yes it was just the GetAMap interface CP. Yesterday I used the printed versions of the 1:25 000. Using a Kodak esp3.2s, which has proven to be an excellent printer both in terms of value (cartridge refills) plus most importantly the quality of print, I printed the area I was working in onto toughprint's outrageously expensive, but does what it says on the tin, 'Toughprint 100% Waterproof paper' and was really impressed with the results.

[Callum]

Lyle, did you get the new mapping direct from OS as I would like to use this at our centre?

[roddyp]

I had a quick look at the HD mapping a while back, and wrote a quick blog post. http://butnoidea.co.uk/2013/03/24/ordnance-survey-hd-mapping/

I've since tried them both on Anquet (PC) and OS Mapfinder (Nexus 7) 

Anquet  printed them well, but looked poor on-screen unless you were zoomed in unfeasibly far.

They looked good on-screen in OS Mapfinder, but in every other respect it's a very poor application. Slow, bloated, expensive maps (esp. the 1:50K) with a minimal feature set.

(First post here. Looks like a useful forum!)
 - Roddy

[captain paranoia]

> Anquet  printed them well, but looked poor on-screen unless you were zoomed in unfeasibly far.

That sounds like a poor digital zoom implementation; going from high definition to lower resolution should allow you to create a good image, provided you use an appropriate resolution conversion filter, and that's not really rocket science.

[roddyp]

Definitely not rocket science now. It was about 30 years ago when I tried to understand it, but that was for real-time digital video processing which at the time required lots of silicon, cooling and coffee...

Here's the offending screenshot inline. See how the vertical weights in "Boat House" are uneven, and - worse - how a grid line has totally vanished due to the pixel-picking.

[Pete McK]

Roddy, if you scale out does the problem resolve itself?