In horror movies, we all know that hidden rooms are dangerous. When a family moves into a new house, and somebody finds a bricked-up doorway in the basement, or a boarded-up closet, it means serious trouble. They won’t find buried treasure -- unless there’s also a curse. Instead, they’ll find a rotting corpse or a doorway to Hell. But in a 3D model on your computer? Who’d expect that? It was supposed to be creepy. It was October, and I wanted to do some scary art for Halloween. I found “Haunted Basement†on sale, and I thought it would be a wonderful setting for some unsettling images. The vendor packed some amazing details into the model. Raise a section of floor in the middle, and you’ll see a hole containing something covered by a gray tarp. Hide the tarp, and you’ll see it’s a skeleton. Hide the cobwebs on the candelabrum sitting on the workbench, and you’ll see that it’s actually a Hand of Glory. There are two red points of light like a pair of eyes in the far left corner of the room, but you can move them anywhere. Happy with my purchase, I picked my favorite character, Malgorzata, to be the “scream queen†in my virtual horror movie. I had her rummaging through the shelves, just about to discover the Hand of Glory. I didn’t like the light, though. It came from the center of the room, which made sense, but it cast her shadow across the Hand. Realistic or not, I wanted her shadow to creep toward the center of the room. I rotated the light four times, making a test render each time. On the third render, I saw an unexpected reflection coming from the opposite end of the room. That was when I noticed the boarded-up window on the far side of the room. With all of the other detailed objects lining the far wall, I had not noticed it before. In size and shape, it was like the upper half of a doorway, but below it was a solid wall. The boards covered just about everything, with only a few shadowy cracks hinting at the possibility of anything on the other side of the window, but in the third render, something reflected back the light I was adjusting in the room. This detail had not been announced on the product page. I had no idea of what might be on the other side of the wall, but I was convinced that the vendor had put something there. I was determined to find it. It did not prove easy, however. The boards were not a prop that could be moved or hidden; they were part of the geometry of the wall. I saw no sign that they were meant to be adjusted by the artist. In the end, I decided to check the material settings. Here was my opportunity: the boards had their own UV mapping. I selected them, and then adjusted the opacity down to zero. Having rendered the boards effectively invisible, I created a new light and directed it into the dark room beyond the window. I selected that light as my camera, and moved it around as a virtual flashlight. The room was strange. The walls were painted black, the floor and ceiling dark red, but the room was otherwise empty. There was no object in the room to create the reflection I had seen. I was disappointed. I had been sure that the vendor had placed yet another grim discovery in the room. Perhaps he had; certainly, it was an unsettling room in which a witch might perform some dark rites, or a ghost might walk, if that were the picture I had meant to create. It wasn’t a bad idea, and I decided to think about doing something just like it. For the moment, though, I had Malgorzata’s discovery to document. I restored the boards’ opacity to 100%, and got on with my rendering. Mags found the Hand of Glory, of course, much to her horror. I created about 30 very fine images, and then I saw that it was getting late. I posed her holding the thing up to the light, gingerly of course, and I saved the file there, intending to continue in the morning. I went to bed, feeling pleased with my work. When I returned to work the following evening, I opened the file, but Mags wasn’t there. I checked the scene hierarchy, and there was no sign of her there: no figure, no hair, none of her clothes. It was as if all of these things had been deleted, and then re-saved. Upon further investigation, this proved incorrect. The Hand of Glory did not hang suspended in the air, as it would have done if Mags and all of her clothes had been deleted; it stood realistically on the basement floor, with a yTran value of 13.23 -- the perfect value to do so. Furthermore, the boards were invisible again. I checked my apartment. This had to be deliberate. There was no sign of forced entry, however, so I considered the possibility of a bug or virus. I tried to import Mags from one of the many saved files I had, but none of them would open. She seemed to have been erased from my hard drive. I opened up a new, basic figure, and applied the Malgorzata files again. Now I had something, but the files had been changed, down to the MAT file images themselves. Her skin was now waxy pale, and her face was contorted in a grimace of terror. My favorite character had been reduced to a rigid corpse. Reviewing the previous day’s renders, I saw the shadows playing at the corners of the frame. Spooked, I deleted the file entirely. It didn’t help. I can see them around me, now, when I look into mirrors. Maybe you can see them at the corners of this video. [End video.] 997 words The choice of the hidden room as my horror-movie trope was very easy; I've seen a number of films recently that used the concept, from classics like The Amityville Horror to recent movies like The Conjuring and Insidious 2. What made this story for me, however, was a flash of inspiration while taking a walk. Instead of writing about a real hidden room, implying an invasion of our living space, it would be a virtual hidden room. Nearly every artist here should be able to relate to it!