At the beginning of this year we defined a vision for 2019 and we also talked about three levels of map development. Although the 2019 vision was not followed for the most part, it is being picked up and pursued much more firmly for 2020. Inherent in that is that the maps will be developed in three levels. This post expands on the initial description given then of what is the Basic level and the intentions to be achieved from it.
The Basic level of the maps is intended to be fully developed for all of New Zealand and it ensures that we have at the very least a full set of maps at this level. It is designed not just to depict the routes of the railway lines in this country, but in fact to supplant and complement existing topographical maps by incorporating most of the key information in these maps that will aid in the use of the maps to locate railway infrastructure easily and quickly. So, Basic level maps include roads, rivers, streams, lakes, contour lines, elevations, place names, property boundaries, bridges, tunnels, and of course, railways. The background of the maps is a set of terrain reliefs. Most of this data comes from freely downloadable layers licensed under Creative Commons by Land Information New Zealand. The real difference off a regular topo map is that we are guaranteeing that the information about the railway system is comprehensive and accurate. It is compiled to a much more detailed level than any topographical map that is available from a mainstream publisher because the maps are specialised to railways.
The Basic maps are published only online and include two separate formats: the basic monochromatic format with terrain relief backgrounds (known as "diagrams") and the identical format with the Linz aerial photography background (known as "maps"). The content at a Basic level is produced by a multi stage process:
- The first stage is to obtain the Linz aerial photography for a volume and then align the railway routes within that volume to the actual rail lines displayed on that aerial photography. For Volumes 1 to 11, these volumes are each based upon one existing main line rail corridor, so the alignment is being done for that main line. For closed branch lines and other rail routes in a volume, we are drawing upon all existing knowledge we have obtained elsewhere about the routes, which may be aided by visible features remaining on the ground that are visible in aerial photography.
- The second stage is to traverse the same routes in the opposite direction and mark in all useful features such as bridges, tunnels, stations and yards. These are all traced off the aerial photography. Our original plan for Basic level has been expanded to make use of Retrolens historical aerial photography for a station site as a reference source to mark in some features that may not be readily visible on current aerial photography. So in this stage the historical aerial photos will help to pinpoint the exact location of individual stations, many of which are closed today.
Right now we are completing Volume 5 to a Basic level and have been working continuously on it for the past few days (of which more in another post shortly). So it looks like a week or two is what it would take to complete each volume to a Basic level. This will vary a lot as some volumes have already been completed at a Basic level, and others have been only partly completed. A lot of volumes were put together before we were able to get the use of the current Linz aerials and of course well before Retrolens came along, other volumes have Intermediate and Comprehensive level content that have been put into them as well. But for now, Basic level is what is happening first.
The maps in general (across all levels) are designed to be highly usable across a range of different formats. The key assumption we have designed them to at the very lowest level is that they will be adaptable both to modern electronic devices and to hardcopy printed formats. For a handheld device such as a tablet or phone, maps will be published online in a photo album with navigational indications that enable intuitive scrolling between tiles. We don't have the means to publish the maps in a digital globe format that can be hosted by a tile server, so the tiles are put into a photo album and statically scrolled and displayed one at a time. They appear at a variety of scales depending on how much detail needs to be shown, so you will see a small scale where there isn't much information, zooming in to a large scale where there is a lot of information such as a yard or siding layout that needs to be displayed.
