Imagine if Oscar voters in 1939 saw "The Wizard of Oz" only in black and white. Would they have nominated the film for best picture and best visual effects if the yellow brick road were just another shade of gray?

The filmmakers behind this year's 3-D movies face just such a dilemma.

Films in 3-D require academy members to drive to a theater, rather than just pop a DVD into their home players, to see the full depth of the work that went into them.

But with a bumper crop of 3-D films up for award consideration, it's not clear how many Oscar voters will make that effort.

"We came out of last year's award season having 'Avatar' overshadow everything," says Jim Chabin, president of the International 3D Society, a nonprofit organization that gives its own awards to 3-D movies. "This year has been scrappy."

Visually ambitious 3-D movies in release in 2010 include "Toy Story 3," "Alice in Wonderland," "How to Train Your Dragon," "Tangled" and "Tron."

Whether in animation or live action, 3-D adds a level of difficulty for filmmakers, particularly in the category of special effects.

Most critics agreed that the 3-D was deployed with particular dexterity in "How to Train Your Dragon," an animated film about a teenage viking who develops a special bond with a monster.

The movie's swooping, kinetic flying scenes earned praise from Los Angeles Times film critic Betsy Sharkey, who called them "a study in how nuance can actually complement the spectacle we've come to demand of 3-D animation."

DreamWorks Animation released "How to Train Your Dragon" in theaters in March and began holding 3-D screenings for members of the academy and various guilds in mid-August.

But its directors, Dean DeBlois and Chris Sanders, must walk a fine line between exhorting their peers to see their movie in 3-D and just hoping they watch it at all.

"If they have the chance to, we hope people will see it in 3-D," DeBlois says. "There was a lot of effort put into the 3-D experience and making it part of the storytelling and not just gimmickry."

3-D is still controversial among the industry's artistic elite, most of whom have yet to make a 3-D movie.

"For the academy, there's some interest, but it's somewhat divided because there are too many projects that come out where 3-D is just used as a diversion," DeBlois says.

Shoddy 3-D has tainted the perception of the format.

Many academy members are old enough to remember movies such as "Jaws 3-D" (1983) or "The House of Wax" (1953), which relied on a more rudimentary technology to create the impression of objects jumping off the screen.

"This digital 3-D today is a completely different technical standard, and the storytelling can be done far more subtly," says Chabin.

"But people have those memories, and it's difficult to change those perceptions."

More recently, the trend of conversions from 2-D to 3-D has raised hackles in the industry, with "Clash of the Titans" drawing criticism for its rushed, second-rate work.

That kind of bad buzz can taint other conversions, like "Alice in Wonderland," which underwent a much longer, more painstaking process.

The year "The Wizard of Oz" was released marked a major change at the Oscars - the creation of separate categories for color and black-and-white cinematography, a distinction that endured until 1967. It's unlikely, says Chabin, that the academy will introduce a 3-D-specific category any time soon.

There is one development due in the next few years that could level the playing field for 3-D filmmakers.

"Someday soon, academy screeners will come in 3-D versions, and you'll be watching them on your 3-D flat-screens at home," Chabin says.

"Of course, the best way to see and experience 3-D, as with most motion pictures, is in a theater with people."