dominoc925

Resolving the no external monitor signal error after updating Ubuntu 24.04

2026-05-11T12:00:00.010+08:00

After installing system updates on my Ubuntu 24.04 Thinkpad P53 with a NVIDIA T1000 GPU, sometimes my external HDMI monitor will no longer get any display signal from my laptop after rebooting. This happened to me many times over the years; and every time I had to search for the solution to the problem. This could take a while and wasted my time. So for posterity's sake, I am writing this post so

Quakemon - Monitor Earthquakes Android App

2026-03-13T09:57:00.006+08:00

Monitor earthquakes, volcano eruptions across countries with Quakemon.Stay informed with up-to-date incidents and live camera views, all presented through an intuitive map and list interface designed for quick situational awareness.Key Features:1. Multi-Countries Earthquakes MonitoringView earthquake incidents across supported countries using an interactive map or a clear, scrollable

QGIS - Display the directions of digitized line features

2025-10-27T15:26:00.006+08:00

When working with line networks in QGIS, sometimes it is necessary to make sure of the digitized line directions for modeling linear network purposes. It is simple in QGIS to display the directions of the digitized line segments; and reverse the direction if required. Basically, to show the line directions in QGIS, simply add a directional arrow marker style to the line segments as described

Take Geospatial files on the go with the Shapefiler App

2025-03-19T09:51:00.001+08:00

Easily load and visualize multiple GeoJSON and Shapefiles with this powerful mapping tool. The app automatically assigns overlay colors, but you have full control over the styling—customize icons, colors, and opacity through the layer properties menu. Tap on polygons, lines, and markers to view detailed feature attributes. Quickly find specific locations with the built-in free text

Use Generative AI to expand an image in Krita

2024-12-16T12:00:00.001+08:00

I was playing around with the Generative AI Diffusion plugin for Krita (https://github.com/Acly/krita-ai-diffusion) but I could not figure out how to expand an image for a while. Eventually, I learnt how to get the job done by doing the following steps, illustrated below.Load in an image you want to expand, e.g. a Halloween pumpkin, in Krita.The image to be expanded loaded in KritaNext, select

Batch Convert Coordinates using the Koordinat2 app

2024-09-30T12:00:00.001+08:00

A batch coordinates conversion tool has been added to the Koordinat2 web app (https://dominoc925-pages.appspot.com/webapp/koordinat2/default.html) to perform bulk coordinates transformation between coordinate systems. This post shows how to use the Batch Coordinates Converter.Launch the Batch Coordinates ConverterUse a browser to open the Koordinat2 web app url (https://

Convert East North Up (ENU) to/from longitude,latitude and other various coordinate systems

2024-09-23T12:00:00.004+08:00

The Koordinat2 web app (https://dominoc925-pages.appspot.com/webapp/koordinat2/default.html) has been upgraded to perform coordinate transformation between local coordinate system East North Up (ENU) and many other coordinate systems including MGRS, North East Down, ECEF, geographic longitude/latitude, etc. This post shows the typical steps to perform the local ENU conversion to

Trainsity Metro App

2024-08-13T15:02:00.057+08:00

Navigate public train networks effortlessly with the Trainsity Metro app's high-resolution vector maps. Choose and download the maps you need, enjoying detailed zoom levels without sacrificing storage space. Access all features offline, without needing an internet connection.Key Features: High-Resolution Vector Maps: Crisp, clear maps with multiple zoom levels for detailed viewing.

QGIS - Finding location by coordinates

2024-05-27T12:00:00.020+08:00

If you need to find specific locations by entering coordinates directly on a map, QGIS offers a handy tool for this purpose. I stumbled upon this feature by chance, and it’s incredibly useful. On the status bar at the bottom of the QGIS interface, there is a field where you can input the desired map coordinates. Here’s how you can use it: Open QGIS: Start by launching the QGIS

Convert Earth Centered Earth Fixed to/from other coordinate systems with this web app Koordinat2

2024-03-25T12:00:00.001+08:00

According to Wikipedia https://en.wikipedia.org/wiki/Earth-centered%2C_Earth-fixed_coordinate_system: in today's modern age of navigation and spatial referencing, there's a key player that often goes unnoticed: the Earth-centered, Earth-fixed coordinate system, more commonly known as ECEF. This sophisticated system, akin to a cosmic GPS, allows us to pinpoint locations with incredible

Convert North East Down (NED) to/from longitude,latitude and other various coordinate systems

2024-03-18T12:00:00.002+08:00

The Koordinat2 web app (https://dominoc925-pages.appspot.com/webapp/koordinat2/default.html) has been upgraded to perform coordinate transformation between local coordinate system North East Down (NED) and many other coordinate systems including MGRS, geographic longitude/latitude, etc. This post shows the typical steps to perform the local NED conversion to other coordinate systems.Define

Deserialize a list of JSON objects using json_annotation and json_serializable in Flutter

2024-02-12T12:00:00.001+08:00

I could not find an example of how to read in a list of JSON objects from a file using the Flutter packages: json_annotation and json_serializable. After a while I figured the way to do it. This post shows an example of automating JSON de-serialization of a JSON file that looks like the following: [ { "code": "NED", "fullname": "North East

How I fixed the Android Studio current target and jvm target compatibility error

2023-11-27T12:00:00.001+08:00

I encountered the following compilation error in Android Studio of one of my Android project about current target JVM compatibility (or incompatibility), as shown in the screenshot message listing below: Execution failed for task ':app:compileDebugKotlin'. > 'compileDebugJavaWithJavac' task (current target is 1.8) and 'compileDebugKotlin' task (

Using Koordinat2 webapp to convert between SVY21 and geographical coordinates

2023-11-13T12:00:00.014+08:00

This is a follow up to the original post https://dominoc925.blogspot.com/2021/02/koordinat2-webapp-for-geo-coordinates.html, which describes a generic coordinate conversion steps. This post shows how to specifically use the Koordinat2 webapp https://dominoc925-pages.appspot.com/webapp/koordinat2/default.html to convert from WGS 84 latitude, longitude coordinates to SVY21 projected easting and

React JS Material UI icons for Mastodon and Blogger

2023-10-23T12:00:00.014+08:00

Other than the Linkedin icon, I couldn't find the Mastodon and Blogger React Material UI (MUI) icons in the React @mui/icons-material library so I had to make my own with Inkscape and a good old text editor. The results are shown in the screenshot below. Here is the MastodonIcon.js code for the Mastodon icon: import * as React from 'react'; import

How to sync the time between 2 Ubuntu systems on an isolated network

2023-06-05T12:00:00.001+08:00

I wanted to match the times between two systems on an isolated network running Ubuntu 22. This can be done using chrony (https://chrony.tuxfamily.org) on the two systems - one system serves as the local time server to the other client system. Setting up the ServerOptional. If chrony is not installed, run the following command in the Terminal to install it.$ sudo apt install chronyUsing a

How to create a Arm64 Ubuntu virtual machine using Virt-Manager

2023-04-03T12:00:00.002+08:00

I wanted to run Ubuntu on an Arm64/Aarch64 virtual machine on a host Intel Linux computer for the longest time for compiling binaries for Raspberry Pis and other SBC boards. I finally figured out how to do it with virt-manager, and it is quite simple as clicking and selecting options on the virt-manager graphical user interface. The instructions below show how it is done.Download and install

Convert a sequence of JPG images into a MP4 video using FFMPEG

2023-03-27T12:00:00.001+08:00

If you have a sequence of images like the screen shot below, it is quite straightforward to use ffmpeg to concatenate them into a single video file. Obviously, you need to specify the image file name and sequence pattern, the frame rate to show each image as shown in the example ffmpeg command below. $ ffmpeg -hide_banner \ -f image2 \ -framerate 1 \

Fixing a kernel panic error when installing Ubuntu 20.04 in VirtualBox

2023-01-30T12:00:00.001+08:00

I was trying to create an Ubuntu 20.04 virtual machine using Oracle VirtualBox but I kept encountering this error with the message "...end kernel panic - not syncing: Attempted to kill the idle task!..." The screenshot below shows the error in VirtualBox.Eventually, I found out the error was caused by inadequate alllocated CPU resources in VirtualBox. By default, the number of CPU allocated for

How to read an array from a ROS1 launch file into a C++ vector variable

2022-12-12T12:00:00.001+08:00

I was having problems reading an array of doubles in a ROS launch file into a vector variable in a C++ ROS1 program node. After some digging around, I found I was doing it the wrong way; instead of using the <param> tag in the ROS launch file, I should be using the <rosparam> tag. The example ROS launch file listing shows the correct way to enter an array, e.g. [0.01, 0.1, 0.2]

Using GIMP to copy an image layer into a channel

2022-12-05T12:00:00.001+08:00

In GIMP, it is possible to copy a colored image layer into a single grayscale channel. Here's how to do the job.Create an empty channelIn GIMP, open up the image file.Click the Channels tab on the bottom right.Then click the Create a new channel icon.The New Channel dialog box appears.Optional. In the Channel name field, type in a name, e.g. flats. In the Fill opacity field, slide to 50.0.

Using GIMP's color channels to remove blue guide lines from inked line art

2022-11-28T12:00:00.001+08:00

Penciled comic book art typically have blue guide lines (and text) as shown in the screen shot below. The sketch can be downloaded from this site https://www.deviantart.com/edtadeo/art/Elektra-2-Pencil-174307445 if you want to practice with it. There are a number of ways to remove the blue lines from the image. I will be using the Color channels panel to remove the guide lines.The

Shell script to batch bulk convert .flac files to .mp3

2022-11-07T12:00:00.003+08:00

I have many music files in flac format and I wanted to convert them to a more compressed mp3 format with ffmpeg on Ubuntu so I can upload them to a storage limited portable music player. To ease the conversion task, I decided to write this simple shell script to do the job. In brief, the script will do the following:find all the files with the extension .flac in the current directoryreplace the

Simple C++ example to send serial AT commands to and receive data from a modem

2022-10-31T12:00:00.004+08:00

I tried using many C/C++ libraries trying to coax a 5G modem to respond to my input AT commands for a long time but I was not successful. The command I was trying to send was the Quectel modem command to query for PDN channels: AT+CGDCONT?After a while, I figured out I had to simulate a keyboard Enter press in code to actually tell the modem the command is complete. So all I had to do was append

QGIS unable to edit SpatiaLite database layer workaround

2022-10-24T12:00:00.027+08:00

Recently I upgraded to QGIS 3.26 on Ubuntu 22.04 and found that I was unable to edit my existing SpatiaLite database layers, i.e. the Toggle Editing tool bar icon could not be enabled. The screenshot below illustrates the problem.While I have not found the cause of the problem, I found a simple workaround to the issue: just create a new SpatiaLite database and import the layers from the old