Georeferencing in QMapShack with QMapTool (video tutorial)
Georeferencing means that the internal coordinate system of a raster image, like a digital map or aerial photo, can be related to a ground system of geographic coordinates. Thus, we can make it appear... Read More
Cartesian Coordinates with matplotlib
In this post we’ll create an orthonormal cartesian plane with x axis, y axis and origin, using matplotlib. If you’re using jupyter first include this line to get inline charts: %matplotlib... Read More
Send a Parcelable to another App on Android
To send a parcelable to another application for it to be deserialized it is essential that: the class definitions of the class to be serialized are identical in both apps, the packages of the classes ... Read More
OpenTopoMap Viewer for Android
OpenTopoMap renders topographic maps from OSM and SRTM data. The style is based on German government maps, with a focus on landmarks and contrasting map colors. This new FOSS Android viewer uses osmdr... Read More
Consuming REST on Android with Retrofit, ViewModel and LiveData
Introduction The first functionality we want to implement in the Ersa Android client is some basic dashboarding. We’ll display the latest temperature and humidity readings by origin (sensor node... Read More
Dew Point Calculation in Java
Introduction The core functionality of the Ersa library is all about calculating the dew point from temperature and humidity data. The dew point is used to assess environmental risks, like mold and co... Read More
A REST API with Spring Boot
Introduction The database structure needed for collecting data in our Ersa software is very uncomplicated. At this point we don’t need any authentication mechanism — we simply need to subm... Read More
A Vertical Slider in HTML/JS/CSS
A while ago my colleagues and I needed a slider control on a web dashboard. A team of students was assigned to build the entire UI, but they did not quite succeed. A third party front-end developer ev... Read More
Android Gauge View
With all these Raspberry Pi and Arduino projects in mind I am developing this gauge view for IoT apps on Android. There are some alternatives around, but I’m not quite satisfied with them as the... Read More
Classic Frogger with libGDX
Roger Engelbert’s excellent tutorial on building a classic Frogger clone with libGDX appears to have gone offline. A couple of months ago I based my own clone on this. It definitely needed some ... Read More