Particle synthesis
From Memory Alpha, the free Star Trek reference.
Particle synthesis is a technology that creates illusory objects, much like holographic technology, but more advanced.
In 2374, Arturis employed particle synthesis aboard his ship, the Dauntless, to simulate a Starfleet appearance. On the bridge of his craft, Arturis could activate a computer command and reconfigure the room to any design he wished. (VOY: "Hope and Fear")
In 2375, Species 8472 used particle synthesis along with holographic technology to create a simulation of Starfleet Headquarters in their terraspheres. (VOY: "In the Flesh")
