Rendering is hard, partly because the real world doesn't look as good as we think it does. I find real phenomena that resemble computer graphics artifacts amusing. Here are some real photographs that look like rendered images, sometimes because the photographer was trying to make it look synthetic, and sometimes because life can imitate the "errors" of computer graphics. Click on the image to see the source, if available; right-click and "Open image in new tab" to see the local copy of the image, in case of link rot. (Begun by Morgan McGuire; his original gallery starts at the break as marked. Newer material curated by Eric Haines.)
The 'Still File' project made this scene to look like a classic Whitted ray trace. The geometric forms and the table's reflection looks too perfect to be real.
That was not the color of caustic that I expected. The studio-level lighting, exotic costume, short hair, and plasticy skin (from makeup) conspire to make this cosplayer read as a high-quality CG render. Source These clouds just look wrong! A thin layer of water on a salt lake creates a mirrored surface that looks like an overly glossy desert sand BRDF. Source This car's mirror surface looks like the material artist got too carried away with chrome. Source Color bleeding? Wireframe? Ambient occlusion? This looks like a beautiful radiosity test. Source These interleaved post-it notes create an effect that resembles z-fighting (thanks, Tomasz). Original at http://i.imgur.com/fhLbgu4.jpg The focused crepuscular rays through the atmosphere created by reflection from that building look fake This carpet's pattern resembles incorrectly assigned texture coordinates or a bug in a projection matrix computation A real, 3D shoulder bag designed in a style that looks like hand-drawn animation A colored glossy reflection creates an unexpected red wall paper pattern (thanks, Pete) Peter Shirley took this photograph in which the glossy highlight on the metal building appears to be too bright and in the wrong place because it is brushed metal (better check your surface normals, Pete!) Adam Sawicki sends this real life shadow that looks like the aliasing artifacts from low-resolution PCF shadow maps. Padraic Hennessey sends these peeled potatoes, which look like they have been ray marched with too few iterations. The reflections in the lake look like undersampled stochastic reflections. From Aras Pranckevičius' blog. Tomás saraceno's net installations look like Photoshop disasters when photographed. This kind of boosted-saturation color bleeding usually only happens in CG. Here's that path tracer reflection test that you rendered (Thanks, Eric). A snowy scene looks a lot like an ambient occlusion-only rendering (Thanks, Mauricio). Eric Haines needs better shadow-map biasing, since he's getting single-texel light leaks. Or maybe there are tiny holes in his window blinds. The camera is exactly at the height of a former flood line, making the picture look like there was a bit error leading to incorrect decoding of the lower scan lines. From The Line by Palindromo Meszaros. (Thanks, Eric) The water is so clear that it looks like the shadow-map bias was cranked up too high (Thanks, Tomasz "Dab" Dąbrowski) Camel thorn trees against an orange dune at sunrise look like a painting (Thanks, Aaron Size) Aliased shadows look like bad shadow map filtering; taken in the stands of a baseball stadium. (Thanks, Padraic Hennessy) Pretty much everything about this image and associated video looks like a modeling or rendering artifact. (Thanks, Tomasz Dabrowski) Basalt pillars appear as hexagonal voxels. Real-world interpenetration (Thanks, Adam) Strobing lights create the appearance of temporal undersampling artifacts on the blurred snow. Federico Diaz's sculpture at MoCA. This image is a visualization; the real sculpture is also made of voxels but has a different shape. (Thanks, Adam) Justin Harder's voxel motorbike (Thanks, Adam) Horizontally scrambled sculpture: forgot your end of row padding again? (Thanks, Eric) Giant 30-story sinkhole in Guatemala is so perfectly cylindrical that it looks artificial Real animated 3D sculpture that looks like a rendered wireframe teapot. (Thanks, Spike) The tree in the midground looks like the Stanford Bunny, a common rendering test object. (Thanks, Adam Sawicki) Looks like radiosity---a fact that was not lost on Cindy Goral. Click through to the comparable image from her seminal thesis. Voxel/oct-tree car--check out the shadow (thanks Eric Haines) Floating man optical illusion / bad shadow map bias (thanks Eric Haines and Pete Shirley) NPR female model (thanks Eric Haines) Synthetic-looking real house (thanks David Luebke) Hard stenciled shadows in the desert again (thanks Eric) "Undersampled" shadows in Pete Shirley's living room due to his window blinds. "L-System Plant" by Adam Sawicki "Percentage Closer Filtering" by Adam Sawicki Eric Testroete's "Low Poly Head" "Voronoi Diagram Model" by Adam Sawicki (although my colleague Frank Morgan would tell you that bubbles are not voronoi!) Benedict Radcliffe's wireframe car. Sara Watson's "invisible car" (from DailyMail). "Undersampled" shadows in the Seattle Public Library's Faye G. Allen Children's Center (picture from the library webpage)