SAN FRANCISCO — Apple is poised to reveal its next big thing Tuesday in a crucial attempt to prove its technological tastemakers still have the power to mesmerize the masses.

The trend-setting company is expected to rouse the still-slumbering market for wearable computers with a smartwatch or bracelet equipped to monitor health, help manage homes and even buy merchandise.

Apple is a late arrival to this relatively new niche: several other companies already sell smartwatches that are being greeted with widespread indifference.

If any company can transform the landscape, it’s likely to be Apple Inc. after the company shifted the direction of digital technology with the iPod, iPhone and iPad.