20 Things You Didn't Know About Star Trek IV: The Voyage Home
11. The Spinning Basketball Was Realised In-Camera But Had To Be Fixed In Post
The Whale Probe in the film is distinctive in its simplicity. A cylinder of immense size, the only identifying feature for which end is which is the sphere that descends from its belly, turning this way and that. Industrial Light & Magic were tasked with bringing this model to life.
First, the skin of the probe was painted so that it would resemble a whale's blubber, then it was lit with various halogen lights and tubes. The sphere that descended was attached with halogen bulbs as well, though there were issues with both parts of the model.
First, the cylinder itself did not come up well on film. This was repainted black, then pockmarked during the re-shoot. The sphere presented a bigger problem for the filmmakers who, despite their initial intention, weren't able to capture it the way they wanted, on-screen. The hue of the sphere came up slightly orange, which made it look, for all intents and purposes, like a spinning basketball.
Every shot of the Probe subsequently needed to be fixed in post, which was the exact thing that ILM had hoped to avoid.