Viewing 16 posts - 1 through 16 (of 16 total)
  • Creating raster maps from scanned paper map – links to good tutorials? and ting
  • nedrapier
    Full Member

    Morning map fans!

    I’ve created small custom maps before, with screen grabs jpegs and geo-referencing with google earth, but now I need to do it with a much larger map, (double sided hiking map, 70km by 35ish, 1:50,000) and probably try a couple of different image resolutions to see what works best on the garmin.

    I’ve scanned it in already, 18 jpegs at 200 dpi. (I’ve read 150 might work better, being the same resolution as the Oregon’s screen, but we’ll see, easy to change in photoshop) They stitch together nicely in MS ICE, but then the image is too big for google earth.

    If anyone can any links to programmes, and/or nice step-by-step guides to creating raster maps so I can merge, reference and split this up (guessing that’s the right order?) so it will play nicely with my GPS, that would be greatly appreciated.

    Thanks!

    Edit – I ‘ve spent a good while on google, there’s a lot out there, but nothing I’ve seen so far does quite what I need.

    And Vectorisation? Seems like a nice thing to do? Any thoughts on that? Is it worth the bother? Is it much extra effort?

    ScotlandTheScared
    Full Member

    Try downloading QGIS. Its a free GIS package which may well allow you to do this (can’t guarantee that though). It has a lot of features though, so worth a try…

    nedrapier
    Full Member

    Thanks Scotland, I’ll give it a go tonight.

    Any other ideas?

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    geoffj
    Full Member

    1. Copyright

    And Vectorisation? Seems like a nice thing to do? Any thoughts on that? Is it worth the bother? Is it much extra effort?

    Depends what the use is, but vectorising a raster is rarely a good idea unless the spatial resolution is sensible.

    Why not just use the free maps from Talky Toaster etc.?

    IA
    Full Member

    Could probably do it with MOBAC, might require some fiddling mind.

    Unless the map is particularly niche you could also use MOBAC to get the map data via another source too…

    nedrapier
    Full Member

    Northern Norway. I’ll check MOBAC, thanks IA.

    plyphon
    Free Member

    We do this all the time all over the building with various vector and raster mapping.

    I work for the OS.

    No i can’t tell you how we do it 😆

    nedrapier
    Full Member

    boo!

    Have you got any advice for the best way someone who didn’t work at the OS could go about it?

    mattsccm
    Free Member

    I haven’t a clue about your terminology so I may be way out here. What do you want to do with the maps?
    I am taking a wild guess and have something that you can plot a route on.
    If so I use TTQV. Its something this is or at least was used for planning motorsport routes and can also produce a road book with either screen shots of the map or you can draw you own road book. Like the Dakar stuff.
    I scan or download the maps I want, 1:50,000 or 1:25,000, calibrate them by telling the software where each corner is after dialing in the correct map format and there you are. Tells me where I am pointing to, to a 12 figure grid ref. I can draw on the maps if I need. What it doesn’t have is anything that allows you to go from a to b by following a road for example. You plot the route precisely. .

    DavidB
    Free Member

    No i can’t tell you how we do it

    Which is utterly crap from a tax payer funded body using a shed load of open source software.

    geoffj
    Full Member

    You can use quantum for the georeferencing – https://www.youtube.com/watch?v=ffPL5h4mJf4

    Not sure whether it is best to slice once referenced or reference individual image files.

    nedrapier
    Full Member

    cheers matt, that’s half of it, I’ve got the map scanned in and stitched together.

    I need to calibrate/georeference it, which I’ve done in G Earth before, but this one’s too big. I’ll try TTQV for this, ta.

    I then need to get it into a format which my GPS unit will be able to use. This is the raster conversion bit.

    Mine, like many, can only handle individual map “tiles” of a certain size eg 1024×1024 pixels – reduces load on graphics memory and processing power/battery life pixels. So you have to split the map up into tiles if you want to load it into a GPS unit.

    A raster map is one that’s made up of many tiles, (can also be layered as well as tiled so you could e.g. have historical aerial photos, contours, roads, hand drawn pirate treasure maps of the same area, overlaid)

    I don’t necessarily need the map on a computer to plan the route on, I can use an online mapping thing just as easily, or even just plan it on paper and remember it – this is ski touring, so distances aren’t long and routes aren’t that complex – initial navigation is broad, exact route finding always needs to be done en route according to conditions.

    All I really want is my position shown on the map on the device while I’m out. The decision to buy the GPS was made in a complete whiteout, near a frozen-ish lake. We needed to circle round the lake and leave it at a certain point to aim for a particular gully out of a number of gullies. We made it OK, but I did feel that more clues would have made the experience a bit more comfortable!

    nedrapier
    Full Member

    David – Hmmmm!

    geoff – ta, I’ll watch that.

    nedrapier
    Full Member

    geoffj, just been getting stuck into QGIS, looks like it’s going to do the business very nicely. The South and the North stitches look too big to import, so I’ll have to reference the individual images. I’m a bit more comfortable with that anyway, just in case the stitching has pulled the edges around a bit. Doesn’t make any difference in use, as they should all be seamlessly overlaid on the device anyway.

    That’s my Saturday morning taken care of!

    Thanks again.

    This is a useful vid if anyone else is interested:
    [video]https://www.youtube.com/watch?v=Cb_qrNh_6_Q[/video]

    plyphon
    Free Member

    Which is utterly crap from a tax payer funded body using a shed load of open source software.

    errr, no, because I’m not in that department. I’m sure you could phone up customer services and arrange a discussion with the various dept. responsible for vector and raster

    however if you want a discussion on mobile UI design and interactive experiences, then talk to me.

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