Greater Christchurch Webmaps [1]

NZ Rail Maps

Good afternoon. As detailed in the last blog post, the current activity being focused on is preparing a webmap preview of the Greater Christchurch area. A set of maps for this area in conjunction with the development of Christchurch Transport Blog and campaigning for the Christchurch commuter train proposals were put together last year but still need work to make them complete. For the webmap preview the focus is on completing them as quickly as possible, perhaps with some streamlining to speed things up a bit, so the additional research done up to the end of last year to identify the names of premises, for example, can be skipped for now.

So far, work has been done on Heathcote, Woolston, Linwood Loco and Waltham. This means that as of now, the yards from Lyttelton through to Addington are ready for the preview. The following remain to be completed:

  • On the Main North Line: Styx, Belfast, Chaneys, Kainga, Kaiapoi, Southbrook, Rangiora. Most of these are partly completed and just require checking.
  • On the Main South Line: Middleton, Hornby, Islington, Templeton, Weedons AFB Siding, Weedons, Rolleston. Middleton and Hornby are the largest of these and will take the most time to complete.
  • On the Hornby Industrial Line: all sidings, Prebbleton, Ladbrooks and Lincoln.

As far as is known, aerial mosaics for all of these areas have been completed, so all that is needed is digitising (tracing the various features into the GIS) off the aerials.

A reasonable estimate of the completion to the level required for the webmaps proposal is therefore about another two to three days. This assumes no significant aerial mosaic correction is needed. To date only some of the mosaics for Heathcote have been corrected, although other errors are apparent here and there.

So it's possible the webmaps preview could be on the site by the end of this week. There are a number of manual steps required to create the map tiles, but at least for Christchurch the existence of some long straight sections of the main line corridor at exactly 90-270 degrees (due west/due east) will speed up the manual part of the generation tasks significantly. The other steps mainly consist of compiling individual tiles into mbtiles files, uploading, and coding the Javascript for the user interface (using the Leaflet.js library).

This preview will include all available aerial photography, which in addition to historic mosaics, will also have Linz colour aerial photography from 2011 to 2018, which has not been made available in any of the other previews so far. The Project is not guaranteeing this will be the level of aerial photography available in the full site when developed; but this level will be included in this preview.

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