[HN Gopher] The art of the shadow: How painters have gotten it w... ___________________________________________________________________ The art of the shadow: How painters have gotten it wrong for centuries Author : webmaven Score : 111 points Date : 2023-02-14 17:38 UTC (5 hours ago) (HTM) web link (thereader.mitpress.mit.edu) (TXT) w3m dump (thereader.mitpress.mit.edu) | nyanpasu64 wrote: | Interestingly, many shadow inaccuracies appear in 3D video games, | due to a combination of rasterization hacks to approximate light | transmission and rendering (player shadows appearing withing | stage shadows, shadows appearing _above_ players standing below a | platform), and deliberate artistic liberties to make games easier | to play (Mario Sunshine 's level shadows are cast from the sun, | but tree and player/enemy shadows appear directly below | characters to make it easier to judge jumps). | mfost wrote: | That's pretty old 3D rendering tricks causing those overall | though. Like I fail to see recent games doing those at all. | | Overall, shadows aren't the hard part nowadays, it's light that | is. Global illumination and light bouncing back around that is. | Though shadows ARE very expensive still. | viraptor wrote: | It's getting better, but correct shadows cast on dynamic | objects are still a relatively recent thing. Can't test now, | but i would bet some modern titles still only do shadows on | static geometry on lower settings. | baabaloo wrote: | [dead] | adwf wrote: | Would've been worth comparing to Vermeer for some examples of | excellent shadows. | psygn89 wrote: | I was told by my art teacher in high school that they | intentionally didn't go for total realism as that was imitating | God's work or some religious reasoning (they cared more about the | story/theme than the execution). I never really bought into that | reasoning 100% as they seem to get really detailed with the | furniture and clothing for instance, but then fall flat with the | perspective/shadows. | dkarl wrote: | > I was told by my art teacher in high school that they | intentionally didn't go for total realism as that was imitating | God's work | | I heard this story as well and always suspected that it was an | urban legend. I heard the same story about a Buddhist painter | who intentionally added a poor brushstroke to every painting, | to reflect that everything is imperfect and changing. Neither | story makes sense in the context of Christian belief or | Buddhist conviction. A Christian would have to be incredibly | arrogant to think they had to take special measures to avoid | rivaling the work of God -- it would be hard to call such a | person Christian. Similarly for the Buddhist. If they believed | that everything that can be experienced has a certain | characteristic, then it wouldn't be necessary to impose that | characteristic on their artwork. | themodelplumber wrote: | This reminded me of my own journey of interest in, and work with | representing shadows... | | After one month of CGI learning, interest levels were like this: | | https://www.creativeshrimp.com/wp-content/uploads/2014/12/cg... | | 15 years later, this is just about what comes to mind when I read | the article: | | https://photodoto.com/wp-content/uploads/2013/01/24-shadow-a... | | Shadows as a concept are, let's say, much more flexible in my | mind now... | | It might have something to do with alternately being told that | some of my real photos were obvs fake, and that some of my | realistically-rendered (per spec) shadows for product marketing | needed to change in the fake direction, in order to fit the | needed composition better. | | After that I decided that all shadows would go in the cow | direction whenever I felt like it, no matter how the scene was | actually modeled. | taneq wrote: | The cow direction is clearly superior. | | Where's the tail come from, though? That's the only bit I can't | figure out. | korroziya wrote: | Slightly misleading title, seeing as how a lot of them were | getting it wrong on purpose. | 6gvONxR4sf7o wrote: | Hopefully the title doesn't turn people off of it, because the | subtitle makes it clearer and article is great. | RC_ITR wrote: | "They did it on purpose" is actually a great answer to "How did | they get it wrong for Centuries?" | shahar2k wrote: | nothing helped me paint light and shadow more than doing 3d | renders and seeing how light bounces and bends in an isolated | environment. | bee_rider wrote: | Lots of comments about how they are probably doing it for | artistic reasons, or as reasonably and ignorable approximations, | which are almost certainly correct. But it is much funnier to | read the headline as inter-field shit talking. | | "Wow painters have been screwing this up for centuries. It only | took a couple decades for programmers to figure out ray tracing. | Git gud art scrubs." | guestbest wrote: | The purpose of the artist with patronages is not to be a camera | but to reflect a more attractive vision of the subject. Also | paintings aren't photography so the artist has more liberty to | alter details to better fit a composition | freitzkriesler2 wrote: | Pretty sure they were doing this on purpose because art prior to | the impressionists was done intentionally to convey subtler | meanings. | | If I recall correctly, it was noses (or maybe it was hands) that | artists had difficulty drawing. Been a long time since my art | history gen Ed. | otabdeveloper4 wrote: | Hands. See Stable Diffusion for proof. | tobr wrote: | Getting shadows right is incredibly complicated. You need to | figure out the silhouette of the object from the perspective of | the light source, then project that silhouette over the geometry | the shadow falls on, then draw the perspective of that projection | from the point of view of the "camera". So it is a perspective of | a projection of a perspective. And to add to that, objects | occlude each other, and you might have multiple light sources. | Since most artists probably start with a composition in the 2d | space of the artwork, there's never really a coherent 3d space to | place the light sources in or figure out those projections in. I | don't think you should expect anyone to get it right in a complex | scene unless they are drawing from reference. | zowie_vd wrote: | > Since most artists probably start with a composition in the | 2d space of the artwork, there's never really a coherent 3d | space to place the light sources in or figure out those | projections in. | | Highly skilled artists don't just think in 2D -- they really do | imagine the 3D scene that they're painting. It's hard to relate | to but people with a lot of drawing/painting experience can | "feel the form", as they say, when they draw. But it's true | that figuring out the lighting is still difficult even then. | | I do want to point out that if you look at talented painters | from later in history than the early renaissance, they don't | make nearly as many mistakes as the ones in the article, | although of course the lighting of imaginary scenes is still | always approximated and simplified. | treeman79 wrote: | Took art class in college a few years ago for kicks. One of | first things is learning to see lights and darks. Spend 3 hours | a day for several weeks in a pitch black room with only a | single source light. Eventually working to drawing a curtain in | charcoal. You don't try and draw a curtain. | | No form to it. You just have to draw lights and shadows as you | "see" them. At end you have a well drawn curtain. | | After awhile your entire perspective even outside of class | changes. You naturally see lights and darks. Not just objects. | waboremo wrote: | You can get a taste of this at home, for anyone else wanting | to experience a new perspective. Find a nice photo of a | person, probably a 3/4 body shot (album covers are great | too), black and white helps but color is just fine too. Flip | the image upside down. Now sketch what you see without | flipping the image or moving your head around, focus on what | you see in front of you as it exists. Don't rationalize it or | think about the grand act of drawing a person. You are just | sketching the dark circle, or a curved line. | | It's a common technique when learning how to recognize lines, | shapes, and shadows. The simple act of flipping an image | upside down is enough for your brain to turn off it's | automatic recognition magic that keeps you from seeing | primary forms. | | Do it enough times, and like other visual artists, you start | admiring a lot of things people take for granted about | vision. | shahar2k wrote: | yup! people draw with "Shortcuts" instead of putting the | actual value of things on the page... my favorite exercise | was dividing a canvas into a 1" grid and taking a 1 inch | brush and filling in each square by mixing the correct color | one at a time like a raster, you end up with a really true to | life pixelated painting. | user5678 wrote: | [dead] | HellDunkel wrote: | Caravaggio and Rembrandt came up with some pretty impressive | shadows- so it always depends on the renderer. What even the | greatest renaissance painters really could not do well is | children! | he0001 wrote: | My main issue with shadows are that they are so hard to color | right. You need the exact same color but you then need to add | black, but I can't get that right. Reflections and such usually | is given away from the scenery. | beardyw wrote: | If you are using paints, not black. You need to desaturate. Get | a colour wheel and add the colour opposite. So yellow, add | purple. It works. | zowie_vd wrote: | I don't recommend adding black to get shadow colors -- you're | not going to get pretty colors if you take that approach. | Shadows have a bit of a color of their own. What you need to do | is think of the bounce light in the scene, and I'll use an | example to explain. | | First of all, if you've got a sphere in deep space, its shadow | side is going to be pure black, since there's pretty much no | light bouncing around, and so there's no light to be reflected | by the shadow side of the sphere. Now let's take an indoors | scene: Imagine a room with red walls, a white floor, a single | neutral (white light) ceiling lamp and a white sphere in the | middle, what color is the sphere's shadow going to be? In the | red-walled room, the shadows of the sphere would be subtly red | -- especially in the parts of the shadow where it's facing the | walls more than the floor. That's because the light you see in | the shadows of an object is light that has already been | reflected from other surfaces in the room. This reflected | light, in the case of the red walls, is red. | | Of course in a more complicated scene you just approximate it. | For an outside scene, you usually want to make your shadows | only a bit darker and move your shadow color's hue a little | closer to the color of the sky. But colors are difficult, you | learn through experience really. | Jaxan wrote: | Not just black but also blue (if outside). De blue sky tints | the shadows blue. | mturmon wrote: | Yes! | | The surface reflects light it scoops up from the visible | hemisphere around it. If some of the hemisphere is sky, then | the light cast onto that surface will be tinted blue. | | I'm not sure if people have access to it, but here's an | example from an airborne imaging spectrometer that is flying | over a partially-shadowed domed building (on the Caltech | campus): | | https://www.sciencedirect.com/science/article/pii/S003442572. | .. | | Figure 4 shows the dome (really a cone) - note the shadow at | top-right. | | And figure 5, panel C, shows the contrast-enhanced light | reflecting off that dome. You can see that the shadowed | portion in the upper-right of the dome is bluer than the | directly-lit stuff. (The directly-lit stuff is more golden, | from the direct sunlight.) | visarga wrote: | No way. Humans are much smarter than SD, are they saying for | hundreds of years we did the (not hands) shadows wrong? | watwut wrote: | Artists today are still getting them wrong. Art education puts | emphasis on this stuff today, but people make mistakes. | hobo_mark wrote: | It still blows my mind that midjourney & co. can get decent | illumination, shadows and even reflections. Just... how?! | onlyrealcuzzo wrote: | Wisdom of the crowd? | | It's just statistically inferring from previously seen | images. | simondotau wrote: | I'm not sure that sufficiently explains an apparent ability | to do three dimensional reasoning when performing | statistical inference in two dimensions? | nerdponx wrote: | Apparently millions of shadows and billions of parameters | is enough. | | Does it always get them right, or just most of the time? | majormajor wrote: | I've definitely seen it get reflections/lighting/shadows | wrong. In exactly that sort of "this is an unusual | perspective and it can't actually do the math" way. | mc32 wrote: | Sometimes you don't want to be "literal" or photorealistic --you | want to portray a scene or subject "artistically" and you take | liberties in order to highlight and de-emphasize other less | important aspects. | | That said, some of the examples are funny, like where a shadow | going up some steps stops short so as not to "overshadow" another | subject[1] --whose shadow in turn seems to be perpendicular to | the main shadow. | | [1]Madonna and Child Enthroned with Saints" (detail) | zowie_vd wrote: | The paintings in the article are mostly 15th century, which is | only early renaissance. The understanding of light in painting | was still somewhat limited in those times. I think in the case | of almost all of these paintings it's more a matter of | technical competence rather than artistic intention (exceptions | include "Madonna and Child Enthroned with Saints" where I | reckon the shadow ends early for compositional reasons). It's | interesting to look at this to get a sense of the various ways | people can get something wrong before someone gets it right. | nerdponx wrote: | It can't be _that_ hard to sketch what you see on a sunny day | or in candlelight and start to make sense of the rules, | right? Getting perspective to look right in paintings seems | like it should be a more challenging invention than how | shadows behave around corners, walls, and other objects. | Getting the sizes and shapes of the shadows correct would be | another matter, however. | | So I am willing to assume that if a shadow fails to climb up | a wall, it's because the artist thought it looked better | without the shadow on the wall. ___________________________________________________________________ (page generated 2023-02-14 23:00 UTC)