Month: February 2019

  • Python Scripting [3D]: Layer Fractional Segments for NZ Rail Maps 4

    Continuing from our last post, we now want to find tile segments that need world files written for them and generate those files.  The code to do this (from the steps outlined previously is: Strip the extension off the base file (92XJ7-92MKF.jgw) so that we get 92XJ7-92MKF: baseNameBase = os.path.splitext(baseName)[0] Split the filename at the…

  • Python Scripting [3C]: Layer Fractional Segments for NZ Rail Maps 3

    Last time we had a look at how to read data from our files and store it in a list. This time we are going to get that data and perform the calculations we need on it. First thing is to convert the numbers read out as strings to floats. The numbers we need are…

  • Python Scripting [3B]: Layer Fractional Segments for NZ Rail Maps 2

    Yesterday we looked at how to collect command line parameters easily in a Python script. Today we need to turn the parameters into filenames and then read their contents to memory. First thing is to get the arguments into variables we can refer to and manipulate. This is pretty simple as the arguments are stored…

  • Python Scripting [3A]: Layer Fractional Segments for NZ Rail Maps 1

    This is a technical description of the scripting project which is for dividing a large layer into segments for NZ Rail Maps. As discussed in some previous posts I am taking for example a 0.4 metre resolution tile and scaling it to 0.1 metre resolution making it 16 times the area of the original. Then…

  • Python Scripting: Planned Scripting Projects

    I’ve written a few posts about different scripts I am planning to look at. At the moment the ones that are most important are: A script to do segmented layer fractions for NZ Rail Maps. I am doing this very slowly and laboriously with a spreadsheet and keep making mistakes and having to paste things…

  • Firefox Developer exhausts system resources

    One week after reinstalling mainpc I had a repeat of the situation that caused the reinstallation. Firefox Developer, which is the main browser I use, somehow got into a situation where it was using full CPU, RAM and swap for a period. I use the KDE system load monitor widget on the panel to monitor…

  • NZ Rail Maps: Optimising Gimp and using 4x4x4 grid for mosaics [1]

    As recent posts have outlined I am using a new grid system for the NZ Rail Maps mosaics to standardise on the use of 4800×7200 tiles for historical aerial images, because Qgis limitations means it tends to run out of memory exponentially more rapidly and be much slower to update the screen if larger sizes…

  • How to optimise Gimp resource usage

    Since I have one computer for the NZ Rail Maps project that is mostly used just for Gimp for mosaic creation and as it has got 32 GB of RAM and 100 GB of Linux swap on a partition of the SSD I need to make sure it uses the available system resources efficiently. One…

  • The end of NZ Rail Maps

    This post isn’t in the NZ Rail Maps blog, nor is it tagged as NZ Rail Maps because it is not an official announcement for the project. I do however expect NZ Rail Maps will last a few more years and then be mothballed. Exactly how many years I can’t say. But after a break…

  • General update 2019-02-15

    Last week I had some issues with mainpc resulting in it running out of /tmp space which of course is caused or impacted by running out of space on the install volume and caused a number of user files in /home I was working on to become corrupted. I haven’t looked at the bigger question…