BSkyB has changed its regulations to allow more 2D-to-3D converted content within programmes broadcast on its Sky 3D channel.

It is a tacit acknowledgement of the high cost and technical difficulties associated with trying to film stereo 3D content entirely natively with 3D rigs.

Its new guidelines allow up to 25% of non-3D content to be used in any 3D programme, up from the strict 10% of converted material written in its original specifications, published last February.

The new rules came quietly into force last year, but Sky has yet to update the specification on the technical section of its 3D website,

Sky said the change brought its 3D guidelines into line with its HD guidelines, which dictate that 75% of content should be in true HD.

It said the change was also about taking a “pragmatic approach to supporting the growth of 3D production in the UK”.

The 2D-originated footage must be HD and in segments that do not exceed five minutes during any 15-minute period.

This only applies to post-converted 2D-to-3D material, and Sky is still adamant that automated conversion of 2D HD programmes to 3D is not acceptable as “original 3D content”.

However, it makes an exception for the use of live conversion tools for certain scenes or camera shots during live events.