Overlay Webmaps Development Preview – Greater Christchurch [2]

Last time we talked about the process of developing a preview for Greater Christchurch and it was hoped we could have it ready in a few days. Now we are a week into this process and although good progress has been made on this task, it’s been necessary to juggle whether to spend time getting the preview reasonably correct before publishing, or just push it out and fix the mistakes later. This meant inevitably the timetable being pushed out.

The conclusion so far has been to fix as many issues as can be reasonably achieved within a capped time frame, and although that time frame keeps getting pushed out, it is only a few days at a time. So far the deadline for completing the map data is now at the end of October, from which it is probably about another three days to a week to prepare all the layers for uploading, and create the custom home page Javascript code to display them.

As usual, the most time consuming aspect is to fix various aerial photo layers, and so far this has been performed in Heathcote, Hornby-Lincoln, Christchurch-Addington and Middleton-Sockburn. As this is written, we have the complete set of aerial coverage for Middleton that have been corrected and have just finished drawing the 1967 layout of Middleton. From there, checking the other generations available at usable resolution (1961, 1975 and 1984 in this case) for changes (which are mainly expected to be in private sidings) follows. Then after that, repeating that process for Sockburn, where the reference generation is 1980, with 1961, 1972-75 and 1984 also being available.

After that it is on to Hornby and Islington which may require more mosaic work. By the time we have finished to Islington, it might be time to decide whether to just create the preview at that point, with only the MSL from Lyttelton to Islington completed (around 20 km) completed, and then add other GC coverage later. It is reasonably certain that it could take weeks to add all of GC and that pushes too much into the planned timetable for other maps previously planned. So completing GC on just a part of the MSL that is within Christchurch City, is the most likely scenario for the preview for the purposes that we want to use it for at the moment.

Overlay Webmaps Development Preview – Greater Christchurch

Good afternoon. Here is this week’s update summary for the NZ Rail Maps Project. So far, in order to aid the development model for the new web site, we have created two different development previews: Volume 1 (North Auckland Line) and Volume 6 (Wairarapa Line). These have reflected several development levels proposed for the maps:

  • The Volume 1 preview demos a map style that has two layers, being selectable from Diagram layers and one era of aerial photography, both available at various zoom levels.
  • The Volume 6 preview demos a map style that has around 16 layers, being selectable from Diagram layers and 15 eras of aerial photography, all available at zoom levels 12-19. It is an advance on the Volume 1 preview by providing for a much greater range of aerial photography in web maps. This has subsequently been modified by adding a transparent overlay for part of the Wellington railway yards.

Last week we started work on a new preview originally proposed to be of Wellington station. With further consideration, we have now changed this to be a preview of Greater Christchurch. The intention is to add four transparent overlays and thus make it possible for users to overlay various levels of symbology on top of their chosen era of aerial base maps. Using the Greater Christchurch area instead enables more evaluation of it by people we work with in Christchurch and with considerably more information included in all of the maps, it will be quite detailed and comprehensive and thus showcase very well what is possible to be achieved in this web maps system. In other words, it will be good advertising 🙂

As we are currently reviewing the completeness of information included in the Greater Christchurch maps and there is a fair amount of editing/updating needed, it will take several days to complete all of the source layers to the preferred standard. Mostly, there are several yards and sidings which have only been partially completed to date, and these will have to be added. Once this work is complete, the generation of the web maps will be relatively straightforward.

As we detailed in previous posts, once the new preview has been completed and any issues corrected, we will be in a much better position to determine what is the best development model going forward. The next stage after that being the development of automated scripts to speed up much of the maps generation from the various volumes. At that point the focus will go back onto actual production versions of Volume 1 (still requiring some digitising work), and Volumes 5 and 6 (mostly completed in a previous format).

So look forward to the Greater Christchurch preview, we expect it to be very good.

Wairarapa Line (Volume 6) Webmaps Preview

Good afternoon. In our last blog post we proposed that web maps for Volume 6 (Wairarapa Line), based on the previously published static images for Volume 6, would become available this week. We are pleased to announce that a preview for part of Volume 6, from Wellington to Waterloo in the Hutt Valley, is now available for use.

Click here to view the preview interactive webmaps for Volume 6

These maps incorporate 15 historical aerial or base layers covering from 1900 to 2009 and these can be selected using a layers control that is displayed in the browser at top right. When the page first loads, Diagrams are loaded and displayed by default, but selecting a different layer in the list available from the layers control will display maps using that particular base layer.

The Volume 6 preview is intended to show how a variety of different eras of aerial photography can be incorporated within the maps. The diagrams and base maps are all available at zoom levels 12-19 and we expect that this will become the standard for NZ Rail Maps webmaps on this site.

As with our Volume 1 preview we are expecting that further content will be added to both volumes over time as part of the development process. We are expecting to develop a scripting system to automate the generation of tiles for the various eras represented in the maps and use this to produce the rest of the tiles needed to complete all volumes. The Volume 6 preview in particular also need adjustments and corrections made in some of the historical aerial layers and captions need to be provided for all of the aerial photos (in the same way as they are presently displayed in Volume 1).

North Auckland Line [0Y]: Weekly Progress Report – Week 42, 2020

Good morning. Last week’s blog referred to samples of Southdown and suggested a method of providing access to specific levels of aerial photography for each station. This week, instead of other map work, time was taken to reflect on further options for displaying aerial photography, and even although another week has gone by with seemingly limited progress, having arrived at what we believe to be a much better solution for displaying aerial content, we don’t regret having waited, for the implementation of this solution will be far simpler to create as it does not require a specific solution for each individual station and is practically seamless for the end user.

Leaflet (the Javascript library that runs in the web browser to provide the user interface) has within it the capability to switch the display to different layers. This includes allowing the selection of different base layers, as well as allowing overlays to be displayed on top of a base layer. By leveraging this capability, we have created sample Diagrams for Westfield-Auckland at zoom levels 12-19, and sample Aerials for the same area and zoom levels from 1972 only. (Although previous demos have gone up to zoom level 20 in aerial photos, we’ve settled on level 19 for now, because of the volume of output that will be produced, so there is enough room on the server to store all of it. Also, we will still have to have some non map galleries for stations that we don’t have aerial maps for, like we were doing for some stations on the Smugmug site.)

The demo web page for demonstrating this multi layer capability is here:


When you go to that site you’ll see this:

This is similar to what our other demo pages have shown, with the zoom buttons top left, but now you have a layers button top right (the thing that looks like a stack of paper). Click on that and a little menu pops up, giving you the ability to choose between Aerials and Diagrams (diagrams is the default). The effect is easier to see when you are zoomed in a bit (maybe to level 17 or so). So now you can go between one and the other seamlessly for a particular location and compare them easily.

In a lot of areas, of course, there is more than one generation of aerial photography available. So the next demo, which will be Volume 6 Wairarapa Line, one of the existing completed volumes, will include multiple levels of aerial photography, and therefore have these multiple layers able to be switched between. We’ll put a post up when that is ready for testing, as it will take a while to format a different project with the webmaps specific styles in the GIS, and export all the tiles needed, especially for multiple aerial eras. For now, enjoy what you can see in the latest Volume 1 demo.

North Auckland Line [0X]: Weekly Progress Report – Week 41, 2020

Good morning. In the last couple of weeks, work has focused both on adding more detail to the maps as is the usual effort, and developing the website. The latter proceeds slowly by steps as it is in effect a completely from the ground up effort which has started from the bare bones of a fully functional LAMPs server with everything except the actual web pages and data files needed to display the maps on screen. Having just been handed a PHP script with no documentation, having to figure out how to deploy it is quite a challenge and the deployment is necessarily being simplified somewhat at this early stage with, for example, static index files that have to have a new line added each time a maps file is created and uploaded, rather than being able to dynamically read the directory and automatically generate an index of it.

After completing the maps for Southdown Station with all the sidings in place, the next determination has been to create sample aerial maps at zoom levels 17-19 as referred to in list posts last week, and testing has suggested these levels, which generate maps taking up 4 MB of disk space, are of a sufficient resolution for useful display without needing to go into zoom level 20 which increases the storage requirement to the point that disk space use is multiplied four times. At this time if a lot of aerial photography is to be uploaded then it is uncertain exactly how much space will be available on the server for this and the rest of the maps so keeping to a lower zoom level is the more conservative option that lets the most aerial photography be added for now.

So having decided on a starting web site design with static hand created html files and duplicates of files like the php script that serves the maps, this standard will be implemented more rapidly going forward, so that more maps will start to be uploaded from here and web pages listing them will start to appear to make the site look like a usual web site with text and hyperlinks to various places.

The aerial map for Southdown in 1972 can be viewed here: