TITLE: Yet Another Reflective Sphere on a Checkered Plane NAME: Tekno Frannansa COUNTRY: UK EMAIL: tek@evilsuperbrain.com WEBPAGE: http://evilsuperbrain.com TOPIC: Before & After COPYRIGHT: I SUBMIT TO THE STANDARD RAYTRACING COMPETITION COPYRIGHT. JPGFILE: yarsocp.jpg ZIPFILE: yarsocp.zip RENDERER USED: MegaPOV 1.2.1 TOOLS USED: HDR probe from http://unparent.com MegaPOV editor Photoshop (to stitch together the 2 images & add border & copyright) Notepad++ (for this text) RENDER TIME: 16 hours approx HARDWARE USED: Athlon XP 3200+ 2.22GHz 2GB RAM IMAGE DESCRIPTION: Before + After I got my awesome povray skills! DESCRIPTION OF HOW THIS IMAGE WAS CREATED: Ok I had to take a liberty with the "before" picture, since I first used pov (and rendered an RSOCP) nearly 15 years ago, pov version 2 running on an Acorn Archimedes, and then didn't use it again until I bough my first PC some 7 years later! In addition to that I've had a couple of catastrophic hard-drive crashes over the years, the end result of which is that the oldest pov scenes I have on my PC are from relatively recently, by which time I was already quite good! I really wish I could have approached this as an attempt to recreate a 15-year old image with my much improved skills, but unfortunately I had to fake the "before" picture. So the "before" shown here is my attempt to recreate the ugly look of the images I rendered back when I was a newbie, though to be honest I've taken a lot of liberties to make it look wrong in all the right ways! Anyway, on to the "after" picture, which is what you're probably interested in. The scene breaks down into a few seperate things: 1/ objects + textures 2/ HDR background 3/ lighting 4/ photographic effects. 1/ objects + textures There's nothing complicated here, all the textures are simple povray procedural stuff. All the objects are very very very simple CSG, apart from the dead leaves & spider plants which are bicubic_patch objects. The textures look real because they obey a lot of physical laws: Reflections on the table & board use conserve_energy to get a realistic gloss. The board has a slightly lumpy normal to make it look less than perfect. There's no specular highlights on anything, since the HDR does a much more realistic effect. The sphere isn't perfectly reflective, and has a normal map to create small imperfections in the surface, and the imperfections are also made less reflective. And obviously the radiosity makes a huge difference to the realism of the scene, so much so that the background objects have just a pigment with no fancy finish effects at all! The underlying pigments of the objects are deceptively simple. Marble is just a granite pattern with a gamma curve (poly_wave) applied to make the veins thinner. The table top is just based on the crackle pattern. The colours of the background objects are chosen to correspond well to similar objects in the HDR probe (by viewing the scene from a wider camera angle so my modelled paving slabs could be compared to the photographed ones in the HDR). Though there's no spider plants in the original photo, they were my own invention because dense foliage is much harder to create & render and would have just shown up as a greenish blur anyway! 2/ HDR background The HDR probe was generated by a friend of mine from photos he took in Japan. It's available free from his website: unparent.com For those unfamiliar with HDR I should explain that all the objects you see in the scene are povray objects I built myself, but most of the other objects visible in the reflections are just the HDR probe, i.e. the scene contains no trees, sky, or buildings, they are just a photo mapped on a dome surrounding the scene. HDR makes this look realistic by having an image with a true linear range of brightness, a conventional (non-HDR) photo would look totally fake if used like this. Megapov supports the use of HDR images and handles mapping them onto the dome. Povray's radiosity responds fairly well to HDR probes but isn't really precise enough on it's own since I wanted distinct shadows, so my final scene has dominant lighting from a single light source in addition to radiosity from the HDR. The main reason I used HDR was for realistic reflections on the sphere and shiny surfaces, the High Dynamic range makes fresnel reflections (like those on the table & board) look very realistic. It also proved very useful for balancing the lighting and colours of the scene, since I had a photograph to compare things to. 3/ lighting As mentioned above, HDR + radiosity did not give good lighting, so I added my own light source corresponding to the brightest part of the sky on the HDR dome. This gives nice clean shadows, with a tiny bit of blur, then the shadows show just the radiosity coming from the HDR dome and light bouncing off objects in the scene. Tree shadows were faked using textures mapped on flat surfaces with no_image no_reflection and no_radiosity, so they just cast a shadow from my light source. This greatly improves the realism of the scene. The shadow on the foreground objects (table, chessboard & sphere) uses a modified image of part of the HDR dome, adjusted to just have the sillouhette of the tree seen when looking at the dome in the direction of the light. The background just uses one of povray's procedural textures to drop most of the BG into shadow, helping to make the foreground stand out. 4/ photographic effects I developed some tricks for my IRTC entry for the Fire + Ice round (my volcano image). I decided to use them again, but this time fixed a lot of bugs (my volcano image is very lumpy & pixelly, whereas this image is very smooth & clean). The main photographic effects are as follows: Focal blur - just pov's standard blur. My final render was at 1600x1200 with 40 blur samples, then resized to 800x600 which gives near perfect blur. The camera's aperture is set to 20mm. Vignetting - simple trick but really effective. Using megapov's post processing I make the image darker around the edge, in a circular pattern (independent of the aspect ratio for the image). This happens in real cameras; I think it's because of the angle of the light hitting the film, at the edges it's a shallower angle so the film gets less light (by n.l, like any lighting calculation). Dispersion - cameras have a lens, and even expensive lenses seperate out the spectrum of colours a little. I fake this using megapov's post processing, by expanding the green image slightly and the red image a little more. The effect is subtle but if you look at the white checks on the left of the image you see their left edges appear red/orange and their right edges are slightly blue. The effect is not an accurate simulation of the distortion from a lens, like vignetting it just follows the rule that the edges will show the effect more than the middle! Tone Mapping - This is the last effect applied, and simulates the non-linear response that film has to light. After a lot of experimentation I came up with a curve that resembles real film fairly well. It's basically an S-bend with a very sharp bottom curve (so colours near black compress slightly, but not enough to darken the whole image) and a fairly smooth top curve (so we have a lot of mid-range contrast without saturating very bright colours to white). In combination with the vignetting & focal blur this really helps pull the foreground objects out from the slightly darker background objects. Incidentally HDR images actually remove the tone mapping from the photos they're based on, to get back to a linear colour-space. These effects (apart from the focal blur) are all acheived & combined using my lens-fx.inc file included with this submission. Right I think that covers everything! I've provided full source, apart from the HDR probe (which is rather big) which can be downloaded here: http://unparent.com/gallery_probeJapanBlossoms.htm Enjoy!