A10 Warthog models feature in the movie but are only seen in the fiery destruction shots as the rest of the aircraft shots are all CG.
1/6 scale models were built by Kerner Optical. They were about 9 feet (2.3m) long with 10 foot (2.5m) wingspans. Masters were built and then molded to produce fibreglass parts. The aircraft models were mounted on rigs to travel forward along with a tracking camera. Three or four cameras were used on each destruction shot with some cameras stationary and panning with the motion.
The opening sequence in the film uses a series of miniature radio telescope dishes that collapse and break apart due to a nuclear blast. These miniatures were used as elements in the composited shots.
Like the rest of the miniatures used in the film they too were handled by Kerner Optical which was a company set up in the old ILM building by some ex ILM modelmakers.
The breakaway dishes were built at 1/12 scale from soft aluminium and polyester resin gel coat. They were collapsed using pyrotechnics and mechanical rigs that pulled them down to the ground.
The mostly destroyed Very Large Array dishes were also built at 1/32 scale for a miniature nuclear blast shot.
The next miniature sequence in the film depicts the collapse of a ruined building as a Skynet Hunter Killer flys past. The 1/18 scale miniature was shot against blue to be composited into the rest of the CG/ matte painted background. The model stood 24 feet (7.3m) tall and was around 10 ft (3m) wide. It was made from pyrocel ( a type of foamed plaster) with aluminium in it. It was weakened in key areas and rigged to be pulled down. It was so weakened by the end of the preparation they were afraid it would collapse before the camera was ready to shoot. The final shot in the movie has so much extra CG dust plastered all over it that it rather spoils the effect.
At the end of the movie is a very impressive miniature destruction sequence. The breathtaking pyro effects orchestrated by Geoff Heron centre around a Skynet tower complex that is situated in a ruined San Francisco environment.
The Tower was built at 1/24 scale and was around 20 feet (6m) high. It had a steel structure and was glazed with microscope slide glass which is very thin.
A series of increasingly larger explosions were timed to ripple up the tower from the ground and shot with multiple high speed cameras from a variety of angles.
After the tower had been blasted there was a subsequent set of radiating blasts that expand outwards destroying the surrounding buildings.
A wider view of the expanding shock wave was achieved with a 1/48 scale model about 50 feet (15m) square that had a blank space where the tower miniature would be composited into and featured a further series of ruined city blocks. The brick and concrete buildings on the miniature set were made from Homasote ceiling tile boards, laser cut into random crumbling shapes and lightly hot glued together. Homasote is a non flammable compressed recycled paper product and it shattered very nicely through all the explosive pyro effects.
There is a very impressive behind the scenes video from Kerner Optical on YouTube that shows the raw miniature footage shot for the film. I find this raw footage more satisfying than the actual shots in the movie as they are clearer, longer and not covered in all the computer graphics elements.
2009 is getting late in the day for wholesale miniature effects in blockbuster movies. While there is a wealth of excellent miniatures beautifully made and lovingly shot in Terminator Salvation many are lost in the quick cutting, or are only smaller elements in a mostly CG image or are hidden by the addition of too much extra CG pasted over the top.
Sources: Cinefex #118 July 2009, Google images, Kerner Optical on Youtube, Sean House -Miniatures in Movies group on Facebook