On the eve of IDFA, international sales rights to Enjoy Poverty were picked up by Vienna-based outfit, Autlook Film Sales.
The provocative, Congo-set film explores the emotional and economic value of what Martens argues is one of Africa's most lucrative exports: poverty.
An eclectic mix of guests is expected in Amsterdam over the next ten days.
Former world chess champ Garry Kasparov will be in town on Friday for the screening of Masha Novikova's In The Holy Fire Of Revolution, a new feature doc exploring how Kasparov's political career was sabotaged by the Kremlin.
African musician Youssou Ndour is coming to Amsterdam for the screening of Youssou Ndour: I Bring What I Love.
Farah, the wife of the last Shah of Iran, has also been invited to IDFA for Nahid Persson's The Queen and I.
Austrian auteur Nikolaus Geyrhalter (Our Daily Bread) has programmed a sidebar of his Top 10 documentaries. Geyrhalter's new feature documentary 7915 KM will be premiering in IDFA's Joris Ivens competition.
There is also a special focus on Indian filmmaking, East Side Stories, which will showcase 17 contemporary Indian documentaries
Meanwhile, commissioning editors, distributors and sales agents will all be in town in big numbers for IDFA's industry events, its coproduction market The Forum and Docs For Sale.
In recent years, IDFA has faced increasing competition from rival documentary events, among them Sheffield Doc/Fest and Dok Leipzig.
Nonetheless, on the eve of this year's IDFA, festival director Ally Derks re-emphasised Amsterdam's credentials.
'I do think it is very important to have one big festival of documentaries - the Cannes of documentaries,' Derks commented of IDFA's current profile. 'This is the biggest gathering of documentary professionals in the year. Also, it is the largest audience that you can imagine.'
The Festival runs from 20 to 30 November.