it. In reference to the cave scene, Delbonnel said, "I wanted to have some kind of 'dynamism' with the light. I thought it could be interesting and more dramatic if the light was floating, circling above the characters faces: sometimes lighting them, sometimes hiding them in a very random and unpredictable way." Visual effects The opening scenes of the Death Eaters' attack on Diagon Alley and London was created by Double Negative, led by VFX supervisor Paul Franklin. Double Negative spent six months surveying and documenting the environment around the River Thames and Trafalgar Square to create the swooping views of the city. Double Negative also contributed to the Pensieve sequences, developing complex directed fluid simulations to realise the swirling world of memory and the past. Tim Burke and Tim Alexander were the visual effects supervisors for the rest of the film. Tim Alexander said that completing the Inferi-attack scene took several months. He said that the scene was much bolder and scarier compared to previous films, and director Yates wanted to avoid making them look like zombies. On differentiating them, he commented, "A lot of it came down to their movement – they don't move fast, but they don't move really slow or groan and moan. We ended up going with a very realistic style." He also noted that Inferi are skinnier than zombies, waterlogged and grey. On Dumbledore's ring of fire to combat the Inferi, he added that research was done on molten volcanoes, among other references. He said, "The visual effects team emulated these six fire parameters: heat ripples, smoke, buoyancy, viscosity, opacity, and brightness." Since the scene was very time-consuming, computer-graphics artist Chris Horvath spent eight months finding a faster way to conjure the flames. Eventually, the final effect would look as though someone sprayed propane and then lit it. Music The film's score was composed by Nicholas Hooper, who also composed the music for Harry Potter and the Order of the Phoenix. The soundtrack was released on an Audio CD format on 14 July 2009, a day before the film was released in cinemas. The album debuted at number twenty-nine on the Billboard 200 chart, thus making it the highest-charting soundtrack among all the six movie soundtracks released. It was nominated for the 2010 Grammy Award for Best Score Soundtrack Album For Motion Picture, Television or Other Visual Media. Differences from the bookHalf-Blood Prince added