South Africa is currently building MeerKAT, a 64 dish radio telescope array, as a pre-cursor for the proposed Square Kilometre Array (SKA). Both telescopes will be located at a remote site in the Karoo with a low level of Radio Frequency Interference (RFI). It is important to maintain a low level of RFI to ensure that MeerKAT has an unobstructed view of the universe across its bandwidth. The only way to effectively manage the environment is with a record of RFI around the telescope. The RFI management team on the MeerKAT site has multiple tools for monitoring RFI. There is a 7 dish radio telescope array called KAT7 which is used for bi-weekly RFI scans on the horizon. The team has two RFI trailers which provide a mobile spectrum and transient measurement system. They also have commercial handheld spectrum analysers. Most of these tools are only used sporadically during RFI measurement campaigns. None of the tools provided a continuous record of the environment and none of them perform automatic RFI detection. Here we design and implement an automatic, continuous RFI monitoring solution for MeerKAT. The monitor consists of an auxiliary antenna on site which continuously captures and stores radio spectra. The statistics of the spectra describe the radio frequency environment and identify potential RFI sources. All of the stored RFI data is accessible over the web. Users can view the data using interactive visualisations or download the raw data. The monitor thus provides a continuous record of the RF environment, automatically detects RFI and makes this information easily accessible. This RFI monitor functioned successfully for over a year with minimal human intervention. The monitor assisted RFI management on site during RFI campaigns. The data has proved to be accurate, the RFI detection algorithm shown to be effective and the web visualisations have been tested by MeerKAT engineers and astronomers and proven to be useful. The monitor represents a clear improvement over previous monitoring solutions used by MeerKAT and is an effective site management tool.

The creation of 3D models for games and simulations is generally a time-consuming and labour intensive task. Forested landscapes are an important component of many large virtual environments in games and film. To create the many individual tree models required for forests requires a large numbers of artists and a great deal of time. In order to reduce modelling time procedural methods are often used. Such methods allow tree models to be created automatically and relatively quickly, albeit at potentially reduced quality. Although the process is faster than manual creation, it can still be slow and resource-intensive for large forests. The main contribution of this work is the development of an efficient procedural generation system for creating large forests. Our system uses L-Systems, a grammar based procedural technique, to generate each tree. We explore two approaches to accelerating the creation of large forests. First, we demonstrate performance improvements for the creation of individual trees in the forest, by reducing the computation required by the underlying L-Systems. Second, we reduce the memory overhead by sharing geometry between trees using a novel branch instancing approach. Test results show that our scheme significantly improves the speed of forest generation over naive methods: our system is able to generate over 100, 000 trees in approximately 2 seconds, while using a modest amount of memory. With respect to improving L-System processing, one of our methods achieves a 25% speed up over traditional methods at the cost of a small amount of additional memory, while our second method manages a 99% reduction in memory at the expense of a small amount of extra processing.

In vorhandener Literatur zum Thema „WebMapping“ wird zwar häufig die hohe Bedeutung von WebMapping-Anwendungen hervorgehoben, jedoch existieren kaum empirische Untersuchungen zur diesbezüglichen Relevanz. Mittels einer offenen Web-Befragung wurde anhand eines Fallbeispiels empirisch untersucht, welche Bedeutung eine WebMapping-Anwendung im Rahmen eines größeren Informationskontextes eines Webportals besitzt. Zudem wurde untersucht, welche Funktionalitäten innerhalb der WebMapping-Applikation als besonders wichtig angesehen werden und welche Wichtigkeit eine mobile WebMapping-Anwendung für die Nutzer besitzt.