Wednesday 18 January 2017

Project Update: Otago Central Railway [1]

Well over the break work first began on updating the MSL from Palmerston to Dunedin and after getting as far as Oamaru work on that has stopped for the time being to focus on the Otago Central Railway. This has been intensified over the last week looking at all areas of the line but naturally the actual map work has been undertaken starting from Wingatui.

At the same time I have been floating some ideas around for publication and it has fallen on me to look at ways of reducing the size of the published volumes down to something more realistic. To do this I have tested two formats that split an A4 page into something long and narrow. The two formats that have been experimented with have been to split the page horizontally into two pieces approximately 285 mm high and 100 mm wide; and to split the page vertically into three pieces of about 90 mm high and 200 mm wide. 

The latter format is the more appealing of the two as it fits more naturally with the shape of regular desktop computer screens, meaning the same format can be used for both. When the images are put into a Flickr album they can be swiped across very naturally and intuitively on a handheld device such as a phone. I tried the swiping thing before but there were issues where the map layout inconveniently had the track exiting the top or bottom of the image instead of the left or right side. To counter this and also make best use of the available space the second innovation is to rotate the maps. This required a rotating north arrow which is a capability that has recently been added in Qgis, so the map will have an arrow in the lower left corner that always shows where north is.

The third improvement is that again Qgis has been updated so that we can have a scale bar that is marked in metres even though the project coordinate reference system (EPSG:3857) uses degrees, minutes and seconds as its units. Seeing an actual distance marked on a map is better for two reasons: it is easier to work out distances with a scale bar marked in metres than it is by trying to do impossible calculations when you don't have anything that inherently tells you how to convert a ratio like 1:8000 into something meaningful, and if the original map is scaled to a different size for some reason, the scale bar distances will also scale proportionately to the new size.

So things have got a lot better than when I first experimented with producing printed volumes that used two A5 size maps that was not an efficient use of space and resulted in up to 150 pages for a volume. The maps that cover the Taieri Gorge Railway for example can be done in about 12-13 A4 pages if that was the format chosen and this is a lot better than what it first looked like. The entire OCR could be done in about 50 pages. Anyway we will have to see where that goes, at the moment I am just pushing ahead with the maps.

Here is a sample of a map with full footer (as will be put on Flickr). For a publication only the scale bar and north arrow would be included. The footer references the new Flickr site I have set up for the maps where the first full set of maps for the TGR can be seen. The example is Middlemarch station (more in the next post).