Mr Palmer's friends have also helped by supplying searchers with photographs from previous trips he made to the area and a boot print has been recovered from his car to help in identifying his tracks.
A University of Otago health science library assistant, Mr Palmer (53) has been missing since Saturday when he set out on what was expected to be a three- or four-hour tramp.
Last night, police confirmed searchers had found "items of interest", which had yet to be officially linked to Mr Palmer.
About 35 people are expected to continue searching the Ahuriri Valley Conservation Park today in specific areas including Mt Gladwish, an 1861m peak, as well as steep gorges with waterways, search and rescue incident controller Senior Sergeant Brian Benn said last night.
Search and Rescue Institute New Zealand development manager Ross Gordon, a key consultant on Lost, was one of three independent experts brought in yesterday to review search proceedings.
Mr Palmer's family members were also shown what was being done at the Birchfield operation base.
Snr Sgt Benn said the involvement of independent reviewers was best practice.
"Largely it is just to get a fresh perspective and a fresh set of eyes. Most searches are solved through initial searches and reflex tasking, but because we have a very large area and difficult terrain we have asked for an outside perspective," he said.
The independent reviewers had international search and rescue experience.
Snr Sgt Benn said searchers had a good idea of Mr Palmer's possible plans after friends and family sent photographs he took on previous trips.
The photographs prompted searchers to consider areas north and south of the Dingle Burn Saddle.
"We know he is a landscape photographer and likes to go to high points of the valley to get pictures. That helps us decide a lot about his behaviour," Snr Sgt Benn said.
"All those little pieces of information go into the mix when creating a person profile, which might help ..."
Despite recent snow falling up to 10cm deep, Snr Sgt Benn said the situation was "very survivable".
