Niagara Falls, N.Y. — A troop of Japanese tourists descends the rocky path within ''spray'' range of the American Falls here, in search of the best picture-taking angle.
In Texas, West Germans hope for a glimpse of ''J.R.'' and other stars of the ''Dallas'' television show shooting on location at a wind-swept ranch. And in New York, foreign travelers visit places like the Brooklyn Botanical Gardens, the Edgar Allan Poe cottage in the Bronx, as well as that old favorite, the Statue of Liberty.
By most calculations, fewer overseas tourists will come to the United States this year, largely because of the low value of many foreign currencies compared to the strong American dollar.
All the same, travel industry experts and officials of the US Travel and Tourism Administration in Washington, D.C., say they expect that the amount spent by overseas visitors who do come this year could well set a new record. According to the 1700-member Travel Industry Association of America (TIAA) that amount will exceed the $12.2 billion they spent in 1981.
Moreover, industry authorities are pointing to two trends that have helped bolster travel by overseas visitors so far in 1982:
* Largely because of aggressive promotion, more foreign visitors are going to traditional tourist spots like Niagara Falls that are now bypassed by many American travelers.
* More overseas visitors are also looking at America's ''back roads,'' either because they saw the more established tourist attractions on earlier trips, or are being lured to places like Brooklyn or Dallas by creative advertising or by television shows that are popular abroad.
''Dallas has become a much bigger international tourist destination because of the TV show,'' says Marie Tibor of the TIAA, ''but elsewhere the US travel and tourism industry is actively pursuing the international market.''
''In the last few years, cities around the US have begun promoting foreign tourism as never before,'' notes David Heinl, president of the International Association of Convention and Visitor Bureaus, headquartered in Champaign, Illinois.
Such efforts partly explain why overseas visitors who came to this country last year outnumbered Americans who went abroad. According to the US Travel and Tourism Administration, 23.1 million foreign tourists came here in 1981, while 22.9 million Americans traveled abroad. However, as industry experts point out, the 1981 exchange rate favored the overseas visitor.
The Niagara Falls Convention and Visitors Bureau now advertises extensively in Japanese and West European tour publications.