As usual, the movies nominated for the visual effects Oscar include such fantastical topics as dreamscapes, superheroes and magic, as well as a simulated natural disaster.

Yet four of the five share a common approach: Photorealistic, with finely detailed imagery.

Realistic vfx are essential for these movies, but even realism is not the whole battle.

For example, Michael Owens, vfx supervisor for “Hereafter,” believed it was key to have the opening tsunami sequence support the story but not overwhelm the emotional content.

“The tsunami scene is really the death scene of one of the main characters so you could never have a moment where you were thinking about what a great visual effect the water was,” Owens says. “You still had to be immersed in what was happening to the character in the story.”

He put those scenes with an eye toward creating an “unpolished” look.

“Once we found a way to render the CG water, we wanted the sequence to feel like it had been shot with someone’s cell phone camera,” he says. “We wanted you to feel like it was happening to you.”

For vfx supervisor John Richardson, making an unreal world look believable in “Harry Potter and the Deathly Hallows: Part 1” meant a seamless transition between the special effects, photographed on set, and digital visual effects added in post.

“During the motorbike chase, for example, there are a large number of physical and mechanical effects and we matched the lighting of the visual effects to the lighting on those real, in-camera effects to make it look more realistic,” says Richardson.

Tim Burke, also a vfx supervisor on “Harry Potter,” made a point of taking a lot of reference photographs of what was being shot to create an HDRI (high dynamic range imagery) reference that would allow the visual effects department to obtain a lot of information about the light in any particular scene.

“The light falling on the effects the same way it falls on the things that are not effects is what makes the difference,” says Burke.

HDRI was also fundamental to creating the look of “Inception,” according to vfx supe Paul Franklin. On set, the visual effects team would take panoramic images of whatever was being shot for lighting reference.

The scanning and capturing didn’t end there. Franklin also used LIDAR (light detection and ranging) technology to get the job done.

“It’s a laser-based version of radar that you can use to scan large art to the resolution of a centimeter,” says Franklin. “We scanned four city blocks of Paris using this technique and this allowed us an incredible amount of detail which we needed because most of the story takes place in broad daylight and you can’t hide things under that condition.”

On “Iron Man 2,” Industrial Light & Magic vfx supervisor Ben Snow also insisted on careful lighting that would create realistic reflections on the superhero armor. The visual effects team would carry the Iron Man suit through a frame in order to get the lighting information from the suit so they could use it later on in their process.

Then they upped the ante even further by using only camera moves that a physical camera could actually make, even if the entire scene is CG and the camera is virtual.

“You used to see a lot of crazy camera moves when you had a lot of CG,” says Snow. “And these would be moves that a camera could never make. So it took people out of the movie because you’d sense something wasn’t quite right.”

More from Eye on the Oscars: Vfx, Sound & Editing:
Editors watch for basics | High notes from sound contenders | ‘Salt’s’ Russell racks up noms | Vfx realism serves story | Wonderland of hybrid thesps