A documentary to be screened tomorrow night reveals that Marzaroli's family has some 50,000 of his photographic negatives.
Mr Marzaroli, who had arrived in this country from his native Italy at a very young age, died in 1988, aged just 55.
The half-hour-long documentary, which is narrated by Bill Paterson, describes him as the 'last great Scottish photographer of the pre-digital age."
He was famous for his many photographs of Glasgow and its people, though he also made regular sorties to the Highlands and islands.
He also recorded Glasgow when the city, and areas such as the Gorbals, were in the process of being transformed.
His daughter, Marie Claire, tells Oscar Marzaroli: Man with a Camera: "After he died I wanted to keep his name alive.
"Even now, 25 years later I still think, my goodness, there's no-one else got a body of photography like this in Scotland, with the kind of passion that he had, but also that sense that all sorts of different kinds of people understand his work, not just people from the art world.
"We have about 50,000 negatives. We've only seen maybe probably about 3000 at the very most."
Tribute is paid to Marzaroli's quiet and self-effacing manner, which, however, did not stop him getting the photographs he was after.
Author William McIlvanney says in the documentary: "He didn't set people up, he just caught them on the move.
"That unobtrusiveness, that quietness of manner, that discretion was, I think, the key to his photography."
Oscar Marzaroli: Man with a Camera, BBC 2 Scotland, 10pm