The overnight sleep-out almost didn't happen, after the Sydney storm washed out the original venue of Centennial Park.

But organisers were delighted on Thursday when the Entertainment Quarter put their hand up to host the event, giving a suitable back-up plan to serve the 6500 ticket holders for the sleep-out.

Retired army officer Lieutenant Colonel Paul Le Large said it was a special moment to share with his daughter.

"I thought it would be good for Tara and I to commemorate the moment, spend a night under the stars. We were grateful it didn't rain," he said.

"Anzac Day is a day where I remember all my colleagues and their families who went off to fight in various theatres of war, so it's an important day for me to just reflect. And importantly for children, so they understand some of the sacrifices."

Tara, 11, said she had enjoyed the sleep-out, in spite of her dad's snoring.

"It was really good [falling] asleep under the stars, which was really nice, it was quite cosy," adding that it was important to remember soldiers, past and present, "and what they did for our country."

The event began on Friday evening with entertainment from artists including Jon Stevens, Mahalia Barnes and Christine Anu, and was one of six overnight sleep-outs held across Australia.

Tickets with a camping plot started at $50 for adults or $121 including food, with more than 7000 meals catered for the event, including bacon and eggs, vegetable fritters and eggplant moussaka.

Organisers were still determining a head count on Saturday morning but expected most of the original 6500 ticket holders to still attend.

Craig Goodman travelled to the event with his family from Maitland, one of the worst hit areas by the Sydney storm this week.

"Mum brought me along, she suggested it. I like camping, so when I heard camping, and to bring your swag along, I thought sweet. Done deal."

He said waking up to the Dawn Service and the call of the Last Post had been a very moving experience.

"I've only been to one dawn service before in my life. So it was pretty cool seeing it on the big screen, it was touching," he said.

"It's the reflection of troops going to Anzac Cove and fighting for Australia, and after one hundred years, it's pretty big."

The last-minute venue change was applauded by many ticket holders on the Camp Gallipoli Facebook page, however others said they were disappointed to learn the event would go ahead after all, as they cancelled travel plans to Sydney on the understanding the event would be held at a late date.

Long before the difficulties brought on by the bad weather, the organisation faced backlash over controversial Anzac-branded merchandise linked to the event.

Three Anzac branded items developed by Camp Gallipoli were recently pulled from shelves at Target after Minister for Veterans Affairs Michael Ronaldson deemed they had breached conditions of a permit the organisation has to sell the merchandise.