The High Museum; Atlanta

Without: a gleaming white porcelain-tiled building, adorned by slinky ramp entries and neatly manicured grassy plots. Within: four tiers of semi-enclosures woven together by simple walkways and bathed in natural illumination from a variety of windows and skylight. White walls and ceilings focus on a central atrium.

One critic has called Atlanta's new High Museum of Art a ''factory gone to heaven.'' An autumn visitor said it looked like something out of Buck Rogers.

But basically, the building's reviews since High's late-autumn opening fall in the rave category. Museum officials hope this will translate into more people , more backing - and nationally distinguished exhibits.

Regardless, High is on the rise. And Atlantans seem to appreciate it. Mayor Andrew Young calls the museum the jewel in his city's artistic crown. A prominent architectural critic terms it Atlanta's ''most important piece of recent architecture.''

The building is set in a residential area just north of downtown along the prominent Peachtree Street artery. Its designer is New York architect Richard Meier.

Meier's trademarks are open space and light. In this case, he sees them as an expression of Atlanta's cultural life. He has scrupulously avoided artificial barriers between exhibits. A visitor viewing a photographic collection is easily tempted to sneak a look at an adjoining sculpture area.

The High's permanent collection includes early Italian and Renaissance, rococo, 19th-century French, American, non-Western, and 20th-century art, as well as prints and photographs and an extensive collection of decorative arts.

Ample space is available for traveling shows. Next year, an overview of 7,000 years of Chinese art will be exhibited. This collection has only been shown so far in Toronto and Chicago. Other exhibits planned for 1984 include: 18th- to 20 th-century French drawings from David through Picasso; contemporary works of black photographers; folk art collections from Ukrainian families; and Richard Devore contemporary ceramics.

A $7.5 million challenge grant from Coca-Cola magnate Robert W. Woodruff launched the rebuilding project for the 60-year-old museum. Matching monies came in from public and private sources to meet a $20 million goal.

High directors visited 50 other museums across the US before deciding on the shape of their new facility. Vikki Baird, development director, says that a prime goal was to create a structure which ''recognized architecture as an art form.''

Another aim was to reach out culturally to the entire region. ''We want to be the major center for the visual arts in the Southeast,'' Miss Baird adds. With its new home and expanded art offerings, the High hopes to swell its number of annual visitors from 300,000 to 500,000.