TREKCORE > VOY > DEMON > Behind the Scenes

	The evolution of this installment took place after the conception of an undeveloped episode of Star Trek: Voyager, involving the "Silver Blood" duplicates of Voyager's crew being welcomed back to the Alpha Quadrant as if they were the starship's crew.
	One of the primary points of inspiration for the episode was that it allowed Star Trek: Voyager's writing staff to feature a planet that was very different from the Class M worlds commonly shown in Star Trek. "We thought it was time to run into a planet that was actually hostile to human life," co-executive producer Brannon Braga recalled, "but holds some mysteries and alien secrets."
	Writer/producer Kenneth Biller described the concept of crew members being physically altered to adjust to a drastically different environment – what The Doctor calls here "bioforming" – as "a spin on terraforming." Biller also said of the episode, "It definitely has an underlying theme about the interdependence between people and their environment." He additionally implied that he enjoyed writing the episode's friendly interactions between Paris and Kim.
	According to visual effects supervisor Ronald B. Moore, the teleplay of this episode described the Silver Blood "as mercury."
	Ken Biller believed that one of the highlights of this episode was its depiction of the Human Kim and Paris socializing with each other, a facet of the episode that Biller enthusiastically referred to as "some good Paris-Kim buddy banter stuff."
	Ken Biller was positive about what little he saw, during the making of this episode, of director Anson Williams' work on the installment. Biller remarked, "From the dailies anyway, [Williams] did a very nice job."
	The set of the Demon class planet's surface included a cloudy sky backdrop.
	For the filming of close-up shots showing Paris' arm reaching into one of the pools of Silver Blood and pulling Kim out of it, Kim's spacesuit was not allowed to be covered in the fluid, as the suits were enormously expensive, so a more elaborate method of creating the sequence was instead used. Ron Moore remembered, "We shot that during second unit [....] We built a big table, and in the table we had an area where we could put the little pool. We had a stand-in for Robbie [McNeill] on the top in a space suit. We had another extra in the arm of a space suit underneath the table reaching up through the hole. So you have [McNeill's stand-in] reaching into the hole, running his hand around, and pulling the other guy up. The hole in the table was covered up, and filled with the goo, and we shot the plate. Once we had the fluid in there, we were dropping rocks to get some surface reaction." These shots would later be augmented with visual effects.
	According to an uncertain account in the unauthorized reference book Delta Quadrant, the physical goo that was used to resemble the Silver Blood was "commercial silver model paint."
	The filming of the scene in which Torres' thumb is recreated by a sample of Silver Blood included a prop thumb on the slide that she and Janeway are using at the time. Ron Moore recalled that this was meant to serve "both as a reference [for visual effects] and to use if we needed to."
	The Demon class planet's cloudy atmosphere was entirely visualized by Digital Muse, a visual effects provider that was also assigned the task of digitally inserting Voyager into shots newly created for this episode. The company received the CG version of the ship from Foundation Imaging, which had been upgrading the digital model while the other organization had made a transition between being Amblin Imaging and Digital Muse.
	An individual who was instrumental in creating the planet's terrain was visual effects producer Dan Curry. While working on the episode, he noted, "I'm doing Macintosh matte paintings of the terrain." Visualizing this environment made use of numerous photographs that Curry and Ron Moore had taken in Lone Pine, during the production of "Basics, Part I" and "II". Moore later reflected, "We would look through those and select the ones which had a good, basic perspective and a place to put a Voyager." Once this was done, Curry significantly reworked the images. "He would drop out the skies, change the ground," Moore commented. "We didn't figure a Demon planet should have tumble weeds and sage brush, so we took all of that out and made the rocks a little more angular." Sky backgrounds that enhance the matte paintings were temporarily planned to be done by Digital Muse. Ultimately, however, the backgrounds were formed from manipulated examples of footage of the sky backdrop used during production – specifically, photographs that Ron Moore had taken while on the set and frames from first unit photography. "We [...] were able to do split screens to keep them moving a little bit," Moore remarked.
	The visual effects elements for the scene in which Paris drags Kim out of a puddle of the Silver Blood were first sent to Greg Rainoff at Digital Magic, before the shots were turned over to Digital Muse. Ron Moore recollected, "Greg made a precomp where you see the hand go into the fluid. He lined up some of the ripples that we had shot. Digital Muse started with that, and animated the fluid around the arm." The artists involved in creating the sequence were attempting to illustrate the Silver Blood as being akin to mercury, matching its description in the episode's teleplay. Ron Moore himself made the fluid slightly more viscous, giving it a slimy finish.
	As well as adding Voyager to some of the episode's shots, Digital Muse also recreated the ship's landing struts with CGI. Ron Moore recalled, "We were going to use the shot from 'The 37's' of the strut coming out on the bottom of Voyager. And Muse thought they could do a much better job. It [gave] us a new angle [....] Muse [...] [added] things like the foot, and the little doors."
	Following the creation of the planetary matte paintings, the process of inserting Voyager into them began. However, Ron Moore initially had some reservations about showing the landed Voyager, having had a regretful experience with the creation of such shots in the episode "The 37's", as the scale of Voyager had been incorrectly estimated. He remarked, "In 'Demon' we spent a lot of time to be correct." Firstly, Dan Curry drew small renditions of Voyager, sketches that showed the visual effects artists which perspectives of the ship were most desired. This artwork was then sent to Digital Muse supervisor Bruce Branit. "Then he could take the [digital] models and put them on," Moore remembered, "and send them back to us. By going back and forth a couple of times we got what we wanted. They'd put the ship in and send it back to us with a matte for the ship."
	It was Ron Moore, rather than either of the visual effects houses, who composited the shots involving the grounded Voyager. This was a rarity for a CGI sequence, though it was far from uncommon for motion control shots to be composited in-house.
	For the scene wherein Torres' thumb is duplicated by a sample of the Silver Blood, both the fluidic sample in its natural state and the recreation of the Klingon thumb were ultimately done wholly via CGI contributed by Bruce Branit and his co-workers, rather than with the prop thumb that had been in the scene when it had been shot. "Bruce and the Digital Muse people did a marvelous job with that," Ron Moore opined.
	The final shot of this episode was also visualized by Digital Muse. "Look closely and you'll see characters down there," Ron Moore observed. "We wanted it to be the whole crew, and I felt like that's what [Muse] gave us. I guess they had some characters they had already created for Deep Space Nine. In fact if you look, you'll see some characters that really shouldn't be there. Seven of Nine you just recognize off the bat, but there are a couple more [....] It's the case where computer people worked better."