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A beautiful code | 14/02/2017
CCFE physicist Scott Silburn is developing a code to calibrate camera views of fusion experiments. But a nice side-effect is that it produces some very nice images, as you can see here.
For the past two years, Scott has been leading the development of Calcam, a program for calibrating camera viewing geometry on fusion devices. The program allows the user to match up features seen in the camera images with those on a computer-aided design model from the drawing office at Culham. From this, the position, orientation, and lens properties of a camera system can be determined. This information can then be used to calculate exactly where the camera's lines-of-sight pass through the plasma, and also which locations on in-vessel components correspond to which positions in the image.
An example application of the code is improved positional calibration for JET's high-resolution divertor infrared cameras, which measure the heat loads at the strike points where the plasma interacts with the divertor tiles. The improved information has been used to improve the accuracy of some of the signals from the cameras, and makes it easier to compare the camera data against other diagnostic signals.
Scott commented: “Accurate camera viewing geometry calibration, including real-world effects such as lens distortion, is an important prerequisite for doing various advanced analysis of camera diagnostic data.
"The idea behind Calcam was to develop a modern, flexible, user-friendly code which can enable this analysis and save time by providing a standard way to do the geometry calibration. But it's also great for making nice desktop wallpapers for my office PC!”
Wireframe parts of JET (above) and MAST (below) fusion vessels rendered using Calcam.
Bottom image: comparison of a real photo of the JET vessel (right) with a synthetic camera (left) used to study the impact of metallic reflections.