Saturday, 5 August 2017

Qgis map development

So as announced on my maps blog I am working to wind the maps project up by the end of this year and I am writing a series of articles that will be published in this timeframe. They will cover the Otago Central Railway but I am working concurrently on updating several different sections of the maps.

As far as general map editing goes with aerial photos I have to use a Windows based edition of Qgis because of there being problems with the Linux edition not being able to load all the aerial photos at once. The Qgis team claims this is a Linux limitation, which I doubt. It may be a limitation of whatever cross platform development system they are using.

I have been using my Windows 10 PC to do this but it has been very slow work and unfortunately I have come to the conclusion this is because the computer's screens are off to one side and I have to work sideways and this slows me down. I can't afford to have this time loss when drawing maps so I am updating a Windows 7 VirtualBox on my main computer so that I can do the maps on this one, it can be given the same 8 GB of memory that the physical computer has. 

The version of Qgis installed on this computer will be 2.99.0-9 (the Windows version number for an earlier development master that doesn't have the major issues that some of the more recent development masters have). There are quite a few advantages to using a VM on my mainpc as all of the other resources needed to do the maps are local to it and they can all be loaded on the mainpc while the Win7 VM is running in just another application window. This is how I do some work already with other VMs running older or different versions of Qgis on different Xubuntu releases.

One issue of both VMs and a physical Windows 10 computer is accessing the map data over the network from MainPC. I helped speed things up on the Win10 computer by putting all the aerial photos into a local drive instead of having them loaded over the network as well. I will set up the Win7 VM with a separate virtual disk for this specific purpose. Of course MainPC's disk space is all being used up with the demands of this project. It has 2 TB of disk space and scary as it would seem that is three quarters used up as of now. Once this project is completed I expect I can recover space by deleting some of the resources like aerial photos as it will be a major expense to add bigger disks as not only would the two disks in the computer have to be replaced but also the two removable backup disks as well. The other option is to move all the music and videos to the mediapc as they are essentially being duplicated on this computer.

The Win7 vbox took a bit of work to set up and make work with two virtual screens and copying the aerial photos across and loading them. It took quite a lot longer to load them than I expected but once it was up and running it has been very easy to do the maps on this computer so it is working well.