UK Coal (IMAGE) Vienna University of Technology Caption Thermal radiation: Usually it depens only on the temperature (coal on the left), But with topological tricks, it is possible to make a surface emit thermal radiation only at certain points, so that a picture can be created, for example a map of the British isles. Credit TU Wien Usage Restrictions none License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.