Palmerston North Gisborne Line [0J]: Volume 5 Progress Update 10

We have now completed the generation of maps of the Palmerston North Gisborne Line mainline corridor. Compared with the progress reported yesterday in progress update 8, Day 5 progress is now a total distance from 228 to 390 km in 5.5 hours, which in comparison to Day 4 is a marathon rate of output. 

However the maps are not yet ready to be released to Google Photos and the website yet. There are a few tasks to complete - we may yet update some of the earlier maps to the new styles (this most affects maps prior to 135 km, and those of Napier Station), and we have to add the mosaic tiles for Gisborne City to Qgis again, so that the aerial maps for this area can be generated in the multiple generations of historical imagery that we created previously - 1948, 1968, 1977 and 1986.

Because the work has gone so well, mosaic tiles are also going to be created for the Waipaoa River Bridge (B290) to show how much it has been changed in its lifetime. Since we have enough aerial photos for all the change period, including some showing the first lengthening work in progress in the mid 1950s, and one taken just after it was lengthened again in 1988, it will be an interesting illustration of the multiplication of this bridge over a 50 year period.

If there is a bit of time, historical imagery of Waipukurau, Woodville and Napier Port are possibilities but since these are not part of Basic level imagery and therefore not a priority, we will have to evaluate our targets to see if we are keeping onto a reasonable timeframe or risk falling too far behind. The Ngatapa Branch maps still have to be created as well, but this is such a short line that it will take no more than a day of work to complete.

The overall task of creating the Basic maps for Volume 5 started on 26 December and therefore it has occupied about two weeks to date. In theory there is a month allocated for each corridor, but some will take longer and others less. We therefore think allowing for one more week to complete this one is reasonable, and therefore that will guide whether we can complete any more historical mosaics given there are also other time demands to be fulfilled.

Palmerston North Gisborne Line [0I]: Volume 5 Progress Update 9

In addition to the production of the maps themselves, a lot of changes have been made to the amount of detail displayed particularly on the aerial maps and in terms of generations of aerial maps.

For certain areas we have chosen to produce multiple generations of historical map tiles. This means that some of the features we trace will be only present in some generations and not others. We did implement and design a system to enable the features to be filtered according to the generation they appeared in. Whilst this is not difficult to operate, it adds complexity when outputting the different map generations.

We decided therefore that in order to make it simpler to output multiple generations of maps without having to filter features according to each generation, apart from having to identify the generation features belong to, we would simply digitise and display all the features across multiple generations in one diagram.

We also decided that we would remove buildings, structures, sites and voids from aerial maps and this information would only be displayed in diagram maps. This would reduce visual clutter on aerial maps and also simplify the production of them.

All aerial maps will therefore be limited to displaying the following layers:

• Locations (Stations, milepegs etc)
• Bridges and Tunnels
• Features
• Main lines (current or former)
• Roads will only be indicated by captions, not actual lines showing their route, on aerial map
• Aerial photography background

Diagram maps will display the following layers:

• Locations (as above)
• Bridges and Tunnels
• Features
• Main lines (current or former)
• Road routes and names
• Footpaths, vehicle tracks etc
• Ropeways, tramways,  pipelines, miniature railways
• Yard tracks
• Buildings
• Structures
• Sites
• Voids
• Property boundaries
• Contour lines
•  Spot elevations
• Place names
• Rivers
• Lakes
• Streams
• Terrain relief background images

 As you can see there is a lot more information in a diagram but it is much less likely to clash with the background. The terrain relief images are a very light grey in colour for the most part and do not visually interfere with the other information displayed as tends to happen with aerial photos. There are also not the issues of features that have been digitised on a map covering up parts of an aerial photo.

 

The new styling will take effect with the production of the Wairoa and later sections of the PNGL main line corridor but at some point will be retroactively applied to earlier parts of the corridor that have been produced to date, once we have had time to bed in these changes.

 

As noted previously a lot of this change is because of the now widespread use of aerial photography in the maps, whereby it has become desirable to determine what is the best way of combining aerial photo backgrounds with the existing information in a map, most of which works well on a diagram format but creates various challenges with an aerial photo background.

 

Below are maps of Wairoa created under the new changes. In our last post we produced 16 maps of Napier out of a total of 24. Given that the maps of Napier covered a total of four actual areas, under the new styling rules, for each area we would have produced the 1973, current and diagram maps, which would have resulted in 12 maps instead of 24.

 

The historical of Wairoa below are aerials for 1942, 1962, 1970, 1979 and current, followed by the diagram. Hopefully this makes the effect of these changes clear enough.

 

 

Palmerston North Gisborne Line [0H]: Volume 5 Progress Update 8

On January 4th we commenced production of maps for the main line corridor of Volume 5, which is the Palmerston North Gisborne Line (PNGL) being 390 km from Palmerston North. Progress rates so far has been as follows:

• Day 1: 0 - 26 km in 1 hour
• Day 2: 27 - 50 km in 1 hour
• Day 3: 51 - 136 km in 5 hous
• Day 4: 137 - 227 km in 5.5 hours
• Day 5: 228 - 294 km in 1.5 hours

 As you can see, productivity has varied a lot but has particularly shown an increase in the last day or two. This is the first large corridor where we have used the Linz aerial photography backgrounds for maps and we struck some issues with alignment of some of the layers that didn't match up the aerial photos, most notably the road layer (which is supplied by Linz as well). These layers were obviously drawn for small scale maps. The net result being with our large scale maps the alignments of roads needing to be extensively adjusted and this slowed down the earlier days of production.

Because nearly every map in urban areas was needing to be corrected we made a decision that on aerial maps the roads would only be displayed with their names and not with the actual physical paths being displayed as lines. On the diagram maps the lines would be displayed. This proved to be relatively easy to implement in Qgis. The result has been no need to fix the alignments except on a small number of maps where it has been a feature displayed on the aerial maps such as a bridge that has not been in alignment. 

On Day 4 although productivity does not appear to be as high as Day 5, we output a set of 16 aerial maps and 8 diagram maps for the Napier railway yard. For the diagrams, there are 2 for each physical area, which is the new and old rail tracks. The Aerial maps have 4 for each physical area, being the old and new tracks and the 1973 and 2015 aerial photo backgrounds, the 1973 ones of course being mosaic tiles from our Gimp project that covered the Napier and Wairoa railway yards. The time needed to compose each view and then change the various parameters to produce the 24 maps total is what slowed the production down on Day 4.

Day 5 has taken us all the way to Wairoa which is only 100 km from Gisborne. We now will have to take a pause to complete some other work, mainly importing the mosaic tiles for Wairoa that were previously created and then outputting the required number of maps for Wairoa, which has in total four different historical generations plus the contemporary generation. We also need to do some other work so things will slow down for the rest of the week but the overall PNGL map generation should be finished by the end of the week.

Below is the complete map sequence for Napier.