Tuesday, 10 January 2017

MSL Waitaki-Palmerston [1]

Well back onto another MSL series. Right now the MSL is not fully detailed between Christchurch and Dunedin. There is about a 60 km gap between Palmerston and Waitaki that is not fully detailed. I have decided to fully detail this section and probably after that, from Dunedin to Invercargill, while waiting for a response to my approach to Railfan Magazine over the Otago Central line project. Detailing this section of line will require adding the sidings and loops between those locations using the Linz aerial photography of the area. Once the photography has been downloaded and added to the map project adding the extra tracks is very straightforward.

So I have just picked out and downloaded the aerial photography for Oamaru to Palmerston, covering Pukeuri, Oamaru, Herbert, Hillgrove, Bushey and Palmerston. I expect it shouldn't take more than today to put in the loops and sidings in these places. Of note is that I have included in the Oamaru download enough coverage to take in the Ngapara and Tokarahi Branches. But I haven't bothered with the Kurow Branch or the Dunback / Makareao Branches.

Palmerston is an area I've already passed in detailing, but I have gone back to put in extra detail. Unfortunately the available coverage isn't detailed enough to see where the siding tracks are. Extra tracks were put in when Oceana Gold began mining at Reefton and railed their ore east and south to Palmerston for processing at the Macraes site inland. This traffic has ceased at the time of writing with the Globe Progress site at Reefton going into care and maintenance wind-down and Palmerston will go back to being sleepy hollow again. The loop at Bushey, the next station north, is where trains have been crossed and when the Taieri Gorge Railway were running locomotive hauled trains to Palmerston a few years ago it was necessary to run on to Bushey in order to run around the train for the return trip. With the extra sidings at Palmerston of late and using a railcar instead of locomotives and carriages it has not been as necessary to use Bushey for this operation. What will get put into Palmerston are the major buildings and the Bushey loop, and I will try to come up with a location for the former turntable (which went to Feilding about ten years ago) as it was still there in 1999 and I have photos of it from that time.

As I noted in my previous post, issues with the current master version of Qgis make for a complex set of steps to add new features to the map. All of the detail work has to be done on my PC, because VMs don't have enough resolution of the mouse clicks to be able to precisely place stuff like on the application running natively on the computer. But, creating new markers, lines or polys in 2.99 runs into problems when saving the new object because of a validation bug to do with certain fields that are present in almost every table of the database. So at that point I have had to install Qgis 2.14 onto my Windows PC and then use that, which is slower because of its low spec CPU and also because it loads the files over the network from the main PC.

This problem was fixed in a later build of the development master but we have a new problem, that there is a limit in the Linux edition on the number of layers which I discovered when I started adding lots of aerial photography images to trace over. So I can only load a certain number of images at a time in 2.99 running on Linux (there is no problem at all with Windows, where I can load 1000 layers easily, but performance is so much slower on that computer) and that has been my workaround to let me keep going with 2.99 on Xubuntu. A further problem has arisen due to issues with the Qt component library that Qgis is authored with and that is that in 2.99 there are rounding issues with the displayed distances on stations (which are stored in the shapefile's database table in kilometres to up to 4 decimal places) - the labelling is showing 42.70 as 42.69999999999999 km which is really annoying. To get around this therefore the actual production of map images has to be done in a VM running an older version of Qgis.