craporola

For 1:25,000 scale maps the only source for free downloads is the Ordnance Survey's Get-a-Map service at http://www.getamap.co.uk. Search for your location then zoom to the maximum scale and use the "Print/Save/Copy" link on the top right of the viewer window to open a new browser window that allows you to right-click and save the image. It looks small and nasty in the browser, but is actually scaled down for viewing. Open the saved file in an image viewer program and it's a healthy 1250x1250 pixels, usually around 700KB in JPEG format. I've found using an image program to convert this to GIF or PNG usually makes the file smaller. The quality isn't as good as scanning a real paper map, but what can you expect for free?

Several other sites used to provide access to 1:50,000 scale OS maps. These have since altered to use flash and javascript applets that overlay lots of junk on the map making them harder to directly download. The only site I know of now that still has large unadulterated 1:50k UK mapping is http://www.streetmap.co.uk. It's visible at the second to maximum zoom level.

However, this site forms the map it shows you in the browser from multiple adjacent image tiles, so if you try to right-click save you only get one km square. So instead you'll need to do a screen capture, crop, and resave as a single image.

A useful tip/hack I have discovered for the streetmap site is that you can hand edit the URL of a presented map to show a wider area than standard, for example the default 1:50k display of this link (trailing stuff from URL snipped for clarity) http://www.streetmap.co.uk/newmap.srf?x=353725&y=146541&z=3
gives a 3x3km view. But change the "z=3" bit to "z=4" and voila.. a 5x5km view - http://www.streetmap.co.uk/newmap.srf?x=353725&y=146541&z=4

I fear for how long streetmap will continue to offer this service as they have a worrying "try our new site" link on their front page which takes you to a version rather resembling multimap...

dr. matt.

If anyone out there wants to volunteer to create a program (in whatever language) that automatically downloads maps from one of the online sources and creates the GPSMap .mcd calibration file automatically (which should be fairly easy for smart folks like you) then please step forward!

This has been a long time project at the back of my mind buy I've never had the time to do something about it. Get in touch if you want more info. Come on, you know you want to!

dr. matt.

The above is the method I use with a very neat Freeware screen/image capture program called MWSnap available here http://www.mirekw.com/

Cheers,

Simon.

hi all

you can alternatively use ZapGrab for screen capture if this is the subject being discussed!! Kindly notify me if the topic i posted is deviating!

Posted for benefit of users to capture maps on-line!

I have experimented with the OS Get-a-Map site with some success and I find the result is better than scanning the original.

My preferred method is laborious but effective. It does need an imaging program with a panorama feature.

I use the method described earlier to save individual 2km by 2km squares of the area of interest - use the Print/Save/Copy option and right click to save to a temporary folder. I then move 1km sideways at a time for five steps - giving 5 images that overlap by 1km. I then use the panorama option in Adobe Photoshop to stich the five into a 6km strip. I then remove the bluse strip and rotate through 90 degrees, saving the new image.
Then I repeat this for another strip 1km south, and then again for another 1km south. The three vertical strips can then be stiched together using the panorama option, rotated back through 90 degrees and saved.
I then use the Microsoft Office Picture Manager to reduce the size of the final image to 65% - this seems to be the size that my HP HW 6915 can cope with.
The final image is 6km by 4km - about equivalent to an A4 section of the original map. With a bit of practice I can save and stitch a sheet in about 6 or 7 minutes.
I still buy the paper map, because the small screen is too small to plan a route with and it eases my conscience.

If you use the Opera browser, you can copy the tiles from the OS Get-a-Map website directly to clipboard, using the right click menu, saving several clicks and delays. Then paste into a blank doc in the image software of your choice [I use paint shop pro and paste each tile as a new layer]. Then line up the pieces properly and merge into one layer and compress to your desired size and format.

I thought it was worth installing Opera just for this alone.

Doog.

http://www.opera.com/

shanks wrote:If anyone out there wants to volunteer to create a program (in whatever language) that automatically downloads maps from one of the online sources and creates the GPSMap .mcd calibration file automatically (which should be fairly easy for smart folks like you) then please step forward!

This has been a long time project at the back of my mind buy I've never had the time to do something about it. Get in touch if you want more info. Come on, you know you want to!

dr. matt.

I have been looking at this as a project to help me get my mind round programming in VB and .net.

I think the key here is to use the URL which provides the save/copy/print page from the get-a-map service. Here is a typical one:

http://getamap.ordnancesurvey.co.uk/get ... bs&isGeo=y

The point is that you can supply a 12 fig GR and get a 1250 x 1250 image at the scale of your choice (defined by the zoom level 1-7) centred on said GR. There are two more parameters one of which I think has to do with the Northern Ireland grid system (isNI) and another one which I don't know about (isGeo).

Given a bottom left and top right Grid reference it would be quite straightforward to loop around retrieving the map images and store them for subsequent tiling ( or use VB or a library (IMagick?) to do the tiling and overlay of the strips (to get rid of the copyright strip - except for the last one)) on the fly and save the resulting image.

If you look at the source of the served page the actual image is a .jpg with a generated id like this:

http://getamap.ordnancesurvey.co.uk/out ... 511126.jpg

The file is obviously produced on the fly and expires after some time. But if you retrieved the file at the time the page was served you shouldn't have a problem.

My thought is to read the page in as a stream and extract the url to the map image and get it directly.

You could produce the accompanying calibration file at the same time. (I assume that you store the co-ordinates in WSGO format and not in OSGB). I have had a look at the source for GPSMap-OS but my C++ is not good enough for me to see the wood for the trees and work out the format of the stored file. There is also the Magnetic Variation value to be entered.

Just my current state of thinking.

btw I use Irfanview and Paint .NET to manually stitch and overlay the tiles together.

I have been trying out another piece of Pocket PC software (GPS-Tuner) http://www.gpstuner.com/ that can display OSGB references from a GPS unit. It is a very good piece of software although I have had problems with it hanging my ipaq 5550.

Anyway supplied with the software (but available seperately as a free download) is a Win32 program which downloads maps from Google and other sources and creates a calibration file for use by GPS-Tuner. Runs fine on XP, vista not so good.

On inspection the file that it produces is a plain text file which includes a list of calibration points (pixel co-ordinates against Lat/Lon). GPS-Tuner seems to require a number of calib points rather than the 2 needed by GPSMap.

However, I have used the information in the file to manually calibrate a map for use in GPSMap and it works fine.

While the Map Calibrator program does not download OS maps, the Google Maps/satellite images are fine for road and urban use. [1]

Would it be possible to explore an option to use the calibration file produced by this program to generate the two calibration points required? Looking for a max X pixel co-ord and then a max Y pixel co-ord would do the business I would think.

This would give an automatic calibration route without re-inventing the wheel.

Kennedy

[1] Work on an OS map downloader continues. I have a perl script which downloads the tiles OK, getting ImageMagick or GD to do the stitching together is not yet complete.

I'm currently testing a program I've written to grab a block of images from the OS website, stitch them into a single Jpg image and create the MCD file. I've tested this for all "zoom" values and 1*1 to 7*7 blocks with my local map on an HTC TyTn II, and it seems to be working fine (except for the files getting too big to load). I need to improve the user interface and add the ability to rescale the image to reduce the file size a bit for larger images (should be able to import this from some other map software I've written, so shouldn't take long).

I delay 10s between file grabs from the website to be "kind".

If anyone would like to test this out, let me know.

What size maps have others been able to load on various devices?

Ken

I'd be up for giving the software a test.

You can get me at kennedy dot fraser at gmail dot com.

Kennedy

Kennedy,
I've emailed you a copy.
Let me know if you don't get it soon - I seem to be having trouble sending e-mail from Pipex to some other systems for some reason.
Ken

I've devleped my program further to have a "proper" view of the map image (pan, scroll, zoom) with the image correctly proportioned, and provided a range of resampling algorithms for reducing the image size so that the best quality result can be used.

I've started adding the ability to overlay multiple trail files in trl, kml and gpx format and to save these back out again in any of these formats.
so far it treats each file a single trail( i.e. doesn't handle gaps), but that'll get sorted next week.

I'm puzzled by the TRL file format though - each Grid ref pair is preceeded by the value 141260 ($227CC). any suggestions what this is?
I can't work it out form the source code.
Ken

Hi Ken,

I suspect the bytes you're seeing are a side-effect of me using the built-in MFC serialization routines to write the trail container, which is declared as

Code: Select all

CList<CPrecisePoint, CPrecisePoint&>

where CPrecisePoint is just a class with two double attributes. The format of the resulting binary file is not officially specified by microsoft and isn't meant for external programs to use; it probably has some kind of class ID before each entry in the list??

The eventual plan of course is to move to some kind of XML format for the trails and map points...

Keep up the development work and please send me a copy of the resulting application - it sounds superb! If you need any more help with this don't hesitate to ask.

dr. matt.

Earlier this year, I wrote a simple Windows program to stitch together a user-specified size of OS map, at a specified resolution, and create the JPG and MCD files ready for download to a Win-CE device. It seemed to work.
Unfortunately, burglars stole my laptop and target device, which suspended development.
I was running a slightly-modified target application on a Navigo SatNav, which you can currently get from Ebuyer for £49.99.

Can anyone tell me where to find the format of the MCD file, please?