Question: What member of Porcupine Tree collaborated with Dirk Series to create Continuum?

full_context: Document 1: Indicates Void: Indicates Void is the name of the fifth studio album released by British musician, songwriter and producer Steven Wilson under the pseudonym Bass Communion, and was limited to 300 12-inch LP copies in handmade sleeves, 100 copies in a silver sleeve, 100 copies in a gold sleeve, and 100 copies as part of a box set of the first 3 "C" releases.
Document 2: The Golden Communion: The Golden Communion is the sixth album by Thighpaulsandra, released on September 4, 2015. It marks Thighpaulsandra's return to solo work after nearly a decade of touring with Spiritualized, Elizabeth Fraser and Wire. The album pulls from over ten years of recording sessions; as such, "The Golden Communion" boasts collaborations not only with Thighpaulsandra regulars Martin Schellard and Siôn Orgon, but also with John Balance and Peter Christopherson, the late founders of industrial band Coil. Overall, the music presented contains threads of psychedelic and progressive rock, featuring orchestrations and extended pop music song structures not heard before on a Thighpaulsandra album.
Document 3: Radiohead: Radiohead are an English rock band from Abingdon, Oxfordshire, formed in 1985. The band consists of Thom Yorke (lead vocals, guitar, piano, keyboards), Jonny Greenwood (lead guitar, keyboards, other instruments), Ed O'Brien (guitar, backing vocals), Colin Greenwood (bass), and Phil Selway (drums, percussion, backing vocals). They have worked with producer Nigel Godrich and cover artist Stanley Donwood since 1994.
Document 4: A Perfect Circle discography: The discography of American alternative rock supergroup A Perfect Circle consists of three studio albums, two compilation albums, one extended play, one video album, nine singles, one promotional single and ten music videos. A Perfect Circle is the brainchild of Billy Howerdel. After hearing demos of Howerdel's music, Maynard James Keenan, the lead singer of Tool, offered his services as vocalist. Howerdel agreed, and the band formed in 1999. They were then joined by bassist/violinist Paz Lenchantin, guitarist Troy Van Leeuwen, formerly of Failure, and drummer Tim Alexander, formerly of Primus. Soon after entering the studio to record their first album, Alexander was replaced by Josh Freese of The Vandals. "Mer de Noms" was released in May 2000, selling 188,000 copies its debut week. The band embarked on a number of headlining tours all over the world to promote the album which was certified gold by the Recording Industry Association of America (RIAA) one month after its release, and platinum just four months later.
Document 5: Coldplay: Coldplay are a British rock band formed in 1996 by lead vocalist and keyboardist Chris Martin and lead guitarist Jonny Buckland at University College London (UCL). After they formed under the name Pectoralz, Guy Berryman joined the group as bassist and they changed their name to Starfish. Will Champion joined as drummer and backing vocalist, completing the lineup. Creative director Phil Harvey is often referred to as the fifth member by the band. The band renamed themselves "Coldplay" in 1998, before recording and releasing three EPs: "Safety" in 1998 and "Brothers & Sisters" and "The Blue Room" in 1999. "The Blue Room" was their first release on a major label, after signing to Parlophone.
Document 6: Storm Corrosion: Storm Corrosion was a musical collaboration between Mikael Åkerfeldt of Swedish progressive metal band Opeth and Steven Wilson, an English solo artist and frontman of the progressive rock band Porcupine Tree. Åkerfeldt and Wilson began a longstanding musical partnership in 2001 when Wilson produced Opeth's fifth studio album "Blackwater Park". The two began writing together for a new project in 2010, releasing their self-titled first studio album on May 8, 2012 through Roadrunner Records.
Document 7: Porcupine Tree: Porcupine Tree were an English rock band formed by musician Steven Wilson in 1987. The band began essentially as a solo project for Wilson, who created all of the band's music. However, by 1993, Wilson desired to work in a band environment, and so brought on frequent collaborators Richard Barbieri on keyboards, Colin Edwin on bass and Chris Maitland on drums as permanent band members. With Wilson still in charge of guitar and lead vocals, this would remain the lineup until 2001, when the band recruited Gavin Harrison to replace Maitland on drums.
Document 8: Continuum (music project): Continuum is a collaborative ambient and drone music project between Bass Communion (Steven Wilson of Porcupine Tree) and Dirk Serries (of Vidna Obmana and Fear Falls Burning). The project looks to expand on the artists' "collective ambition and vision, motivated by their immense passion for a wide-range of musical styles, ranging from spacious ambience to pounding doom metal."
Document 9: The Alan Parsons Project: The Alan Parsons Project was the collective reference to several lineups of a British progressive rock team, active between 1975 and 1990, whose rosters consisted of Alan Parsons and Eric Woolfson surrounded by a varying number of session musicians and some relatively consistent band members such as guitarist Ian Bairnson, arranger Andrew Powell, bassist and vocalist David Paton, drummer Stuart Elliott, and vocalist Lenny Zakatek.
Document 10: Emerson, Lake &amp; Palmer: Emerson, Lake & Palmer (ELP) were an English progressive rock supergroup formed in London in 1970. The band consisted of keyboardist Keith Emerson, singer, bassist and producer Greg Lake and drummer and percussionist Carl Palmer. With nine RIAA-certified gold record albums in the US, and an estimated 48 million records sold worldwide, they were one of the most popular and commercially successful progressive rock bands in the 1970s, with a musical sound including adaptations of classical music with jazz and symphonic rock elements, dominated by Emerson's flamboyant use of the Hammond organ, Moog synthesizer, and piano (although Lake wrote several acoustic songs for the group).
Document 11: Up the Downstair: Up the Downstair is the second studio album by British progressive rock band Porcupine Tree, first released in May 1993. It was originally intended to be a double album set including the song "", which was instead released as a single in 1992, and other material that ended up on the "Staircase Infinities" EP (1994). In 2005, it was partially re-recorded, fully re-mixed, remastered and re-released along with the "Staircase Infinities" EP as a double album. The re-release contains a new mix by Steven Wilson, along with recorded drums by Gavin Harrison that replace the electronic drums of the original version. Steven Wilson has stated that the title of the album came from a line in the song "Voyage 34." There is still a title track, however. Another re-release on double vinyl was pressed on 14 August 2008 on Kscope records. This is identical to the 2005 release, except it is printed on coloured vinyl and the "Staircase Infinities" disc contains the song "Phantoms".
Document 12: Slave Ambient: Slave Ambient is the second studio album by American indie rock band The War on Drugs, released on August 16, 2011, on Secretly Canadian. Recorded over three years, "Slave Ambient" is the final release to feature contributions from founding guitarist Kurt Vile and drummer Mike Zanghi, and the first to feature drummer Steven Urgo.
Document 13: Untitled (Bass Communion Box): Untitled (or box set) is a box set compilation of songs released by British musician, songwriter, and producer Steven Wilson under the pseudonym Bass Communion. It contains many rarities from the last 15 years of Steven's ambient and drone work, especially from vinyl only editions of Bass Communion albums. It also features the previously unreleased track "Temporal", recorded in 2012 as a homage to composer Harrison Birtwistle and his 1971 composition "Chronometer" – both pieces are created entirely from the sounds of clocks and other timekeeping devices.
Document 14: Steven Stapleton: Steven Peter Stapleton (born 3 February 1957 in Finchley, London, England) is a British musician and the only constant member of experimental improv outfit Nurse with Wound. He is often seen as one of the pioneers of the British industrial music scene, alongside bands such as Throbbing Gristle, Coil and Psychic TV, although in his music he has explored a wide range of styles, including free-form improvisation, folk, and even Latin American dance rhythms.
Document 15: Ben Chasny: Ben Chasny is an indie rock and psychedelic folk guitarist. His primary projects are Six Organs of Admittance (his solo psych folk project) and Comets on Fire (a psychedelic rock band). He made his recording debut in 1996 with his heavy, free rock project Plague Lounge on "The Wicker Image", an LP released conjointly between the New World of Sound and Holy Mountain labels. Holy Mountain went on to become the "home" of many of his releases under the Six Organs Of Admittance moniker. He has also released an album with Hiroyuki Usui under the name August Born. Chasny has lent his talents to other projects such as Badgerlore, Double Leopards, Current 93 and Magik Markers both in live performance and studio albums. More recent musical projects of his include the avant-folk trio Rangda (along with guitarist Richard Bishop and drummer Chris Corsano) and the more melodic and conventional 200 Years with Magik Markers' Elisa Ambrogio.
ground_truth: Steven Wilson