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!