CRYSTAL VISION’S SAFIRE DIGITAL CHROMA KEYER CHOSEN FOR TV WEATHER BROADCASTS (August 2005)

BBC Weather is using three Crystal Vision Safire digital chroma keyers to produce its national weather broadcasts.

In May 2005 following feedback from viewers, the presentation format of the weather broadcasts was dramatically updated to include exciting 3D animated graphics and virtual reality technology. Central to the theme is a 3D globe and a unique view of the entire UK. A tour of the nation and individual regions offers viewers more details about the weather in their particular area.

Crystal Vision’s Safire was selected to perform the chroma keying for the weather broadcasts. Unusually instead of the presenter standing in front of a solid blue or green screen, they are positioned in front of a translucent screen, the back of which is flooded with blue light. The chroma keyer then detects this blue light and replaces it with the graphical weather charts used by the presenter during the broadcast. The presenter also has the advantage of visualising a very faint copy of the chart projected onto the translucent screen, which they can use when orientating their presentation. The final image seen by the viewer will be that of the presenter standing in front of the graphical charts.

The UK national broadcaster produces around 100 weather broadcasts a week viewed over six terrestrial channels (BBC ONE, TWO, THREE, FOUR, News 24, and BBC World). There are three weather studios each of which required a Safire chroma keyer, with all three Safires being controlled by a dedicated 2U Safire Controller.

Alongside the changes made to the visual effects, improvements were made to the studio’s interface and signal processing equipment. Eleven Indigo 2 frames are used to house the 57 Crystal Vision interface boards purchased on this occasion. Included on the order were ENC116 and MON210 encoders, ShARC-XP aspect ratio converters, ADCA412 and DACA214 audio converters, AADA416FM quad analogue audio distribution amplifiers and DEC101S and DEC104S decoders. Unlike other chroma keyers, Safire is designed to form part of a modular system, which means it could be housed in the same frames as these interface products, consequently reducing the amount of space required.

Safire as a hardware digital chroma keyer is ideal for use in live TV. In addition to chroma keying, Safire offers linear keying, mixing and wipes either as stand-alone functions or within the chroma keying to create virtual outputs. Safire offers both multiplicative and additive keying and sophisticated shadow processing, enabling the intensity of shadows to be precisely adjusted to produce a realistic final effect.

Based at Whittlesford near Cambridge in the UK, Crystal Vision provides digital keyers and a full range of digital and analogue interface equipment including converters, decoders, encoders, distribution amplifiers and audio embedders to the professional broadcasting industry worldwide.