Tuesday, 26 June 2018

Map production update

People who have been following this project for a while know that we did issue map collections for a considerable portion of New Zealand when we were using Flickr to store these collections. As a result of the reorganisation of NZ Rail Maps resources when the website was set up, the Flickr collections were taken down and replaced by Google Photos albums.

Since that was carried out, the previously generated map collections have, for the greater part, not been republished in Google Photos to date. We are now planning to re-issue the previous maps (diagrams as we now call them) for as many lines as they are currently completed for. These will be published to the latest template standard but the map data in them will be largely unchanged. However where addition of new data has been partly completed a decision will be made on whether to republish as is or complete the addition of new data before republishing.

The current project for updating the maps is largely focused in two areas:
  • Tracing over current Linz aerial photography, and using that as a map background
  • Adding additional content to the maps from historical aerial photos and using these photos as map background.
This work will be ongoing. The first step is relatively straightforward in mapping but does require significant preparation in downloading and selecting the aerial photos needed as a background for a particular volume of map production. The second step is more time consuming as georeferenced mosaics have to be created for a particular location of a route (such as a station, yard or depot) and then traced over with the additional detail added in a way that makes it possible to publish multi generational maps for the specific location. Hence the update aspect of the project is slower in terms of the publishing of content.

Map volumes will be published for each volume as the aerial photo based maps are completed for the entire volume. There are twelve volumes whose content is listed on the home page of our website. Some of these volumes have been published over the last four years, mostly as diagrams. The Nelson volume which has been published more recently uses aerial photo backgrounds as an experiment. 

There are two main types of published content for the maps. These are:
  • Rail Maps - these show the map data published over a background of current and historical aerial photography. They are most suitable for use with electronic devices where the full colour of the aerial photographs can be viewed without limitations.
  • Map Diagrams - these show the map data with a plain white background. Diagrams are ideal for use where there is a need to have a physical format such as by printing individual maps that are downloaded off the web or by printing out one of the map volumes that are produced for a particular group of routes.
As noted above we have experimented with using both formats in map volumes. However, the intention when producing map volumes has historically been geared towards a printed solution for those users that wish to have a physical variant of the maps. The aerial photo background used in the recent Nelson volume is really only of use when viewing it on an electronic device and the volume format in a PDF file is sub-optimal for field navigation because of the layout of individual pages that frequently contain multiple maps for efficient use of space. The use of colour content in the maps is also contrarian to easy and cheap printing as the colours will not always reproduce well in black and white printing or copying, and colour printing is often too expensive for many people. Hence, we expect that map volumes produced in future will all be based on diagrams.

Rail maps are currently published using Google Photos. We have discovered that it is possible to download a complete Google Photos album as a zip file to a device. For field use, this is the optimal solution and the photos in each album will be named in a numerical series that makes it easy for them to be browsed using a picture viewer that relies on alphanumeric sorting of the images. As previously described in the last post about field testing, the banner that has been added to the top of the more recently produced maps will have directional labels added to it to make it easier to navigate with a collection of maps on an electronic device, whether online or offline.