Lights seen through glass

(theoldghost) #1

Given the interest in photo-realism a disclaimer might be in order. This is the first shot in a animation for the family and photo - realism is not even a consideration. Hell for that matter I’m not using Filmic because saturated color is the order of the day.

The lighting in the place is area lights with mesh lights for the camera and what you see in the overhead is the actual lighting. And, when I move the camera inside and lower the value of either it is obvious. But, not so outside here where the lighting is coming through glass. Regardless of the value set on the interior lights what you see in the glass does not change.

And, I suspect I have changed every setting known to a Blenderhead and tried every glass material YouTube has to offer with the same results. The brightness / intensity of what is seen in the glass does not change. Regardless of what level the interior lights are set to.

(Daedalus_MDW) #2

have you bern able to reproduce this in a simplified blend? have you tried other blender versions?

(theoldghost) #3

Daedalaus_MDW thanks for taking the time. To be frank I moved the file to 2.79 a couple of months ago and am now committed to this version. I would be reluctant to even rename the file and try 2.78 again. Which doesn’t have the denoiser I might add. Lukas has given me something I can’t do without since this is going to be animated.

(Daedalus_MDW) #4

i dont really care if you have to use 2.79.

the whole point of testing old versions is to find out if this was broken at some point in time. if it was, it would help greatly to narrow down the offending change.

but we really need to know if this is a bug or a current limitation. create a simple blend and ill be happy to poke around at old versions with it.

(theoldghost) #5

Same results in 2.78c. For anyone reading this change any Principled Shaders before taking a renamed file back to a earlier version of blender. I left the one on the floor and the CPU fan sounded like it was coming through the case. Regardless the results with the lights were the same.

(minoribus) #6

Hello Ghost,

to which value did you set the bounces for transmission under Light Paths in the render panel? I had the same issue down in the harbor at some time when I and increasing this value did help. Maybe you’ll have to play with the transparency values also.

(theoldghost) #7

Thank you my old German friend for taking the time. And, I faintly remember the harbor. The greatest short that never happened if I remember correctly. (]:-) But, a ongoing tutorial nevertheless. And, a post I still visit on occasion for exactly that reason. But, in response to your question that doesn’t seem to be the case. And, I do remember you having a time with the glass doing The Harbor. And, never really being satisfied if I remember correctly. Leaving me to wonder if that would be the case in 2.79. Once again thanks for stopping by.

(burnin) #8

Seems working fine…:confused: or is this not ok?

note: This lighting demo shows animated opposite values (as shader/geo decreases the lamp increases in strength).

Strength values don’t have equal influence (even if same surface area & textures are used). Lamp is darker than Emission shader using same value & texture/color.

To have Lamp invisible looking through glass, disable Transmission Ray Visibility in Cycles Settings.

(theoldghost) #9

burnin, by god you have it. Thanks guy but honestly I couldn’t understand your explanation. I must be having one of those senior moments here. Anyway this is what I stumbled on and it might be exactly what you did.

Finally my dumb ass realized the unchanging values on the glass were the actual area lights which are invisible to the camera. So cutting Transmission off took care of that. They are still lighting the interior however. Then it was simply taking the mesh lights down a notch and checking Transmission for them once again in ‘Cycles Settings’ I also discovered personally I didn’t want them much dimmer. But, enough where they differed from the outside lights. The results are good for me since I’m dealing in plausible reality as I call it. And, at eighty don’t really see Pixar in my future. Once again thank you all for taking the time.

(sundialsvc4) #10

For what it’s worth (and, “I mostly use BI”), the most-efficient workflow that I have found to “do glass” is to fake it.

“Real, accurate” glass-work can be very expensive. If you’re doing a belle arts single-frame shot that’s going to be admired at very close range for its perfection, maybe so. If you absolutely have to do refraction or distortion through a thick piece of glass, you might also be stuck. Otherwise, I suggest that [panes of …] glass come down to basically two things – both having to do with “inside vs. out”:

  • Reflections: This basically tells the eye that “there is a piece of glass here.” Put a camera where the glass is, facing out, and shoot one frame. Use this as a texture on a transparent plane (i.e. use only the “texture” output). Invert left-to-right if need be. Use a curves-node to adjust the density and fall-off.
  • Hue and Saturation: This says, “it’s inside that warm house and I’m out in the cold.” Anything visible “through the window” will be seen with less hue and saturation, and might also need a color-cast. When you render what’s “inside the window,” the pane is not there. The modifications are applied (in post-processing) to the area that is occluded by the “window-pane plane.”

(burnin) #11

Sorry, you’re impression is right, i gave no explanation. Usually i only hint & point the direction for mind to explore on - learn.
Even at 80 (= you’re vital & encouraged to dwell further… respect.

Everything we know is fake, our knowledge is an approximation of the truth optimized to the most efficient possibility at mind… that’s the evolution baby. :smiley: Personally i love to know about behavior of all kind, even of rays. We are only able to strive for the truth via connections in our brain. Rays get banded through matter :wink:

(sundialsvc4) #12

In the world of CG, “‘Fake’ is ‘Good!’” :yes: If you can find a cheap-and-fast way to produce a result that is “good enough,” do so without apology.

I think that a lot of people try to “model physical reality,” then they wait for hours as the renderer dutifully grinds through it. And the results, if(!) they did it perfectly, are, of course “perfect.” But there are also times where it is quite acceptable to consider what the final shot needs to “look like, in order to be convincing enough, and to “cheat” your way there.

In the original theatrical release of Star Wars Episode One, a crowd in a podracer sequence actually consisted of colored Q-Tips® cotton swabs. Since the audience had seen an actual crowd a few shots before, no one “saw” the Q-Tips until the trick was pointed out in a “making of” featurette. (The shot has since been replaced.) Animations, especially, have lots of “passing scenes” that simply don’t deserve time-expensive treatment.

(fitz301) #13

Agree 100%…

Reality has already been done, that’s what we invented film and video for.

CG is a tool to tell your story, nobody is going to question the accuracy as long as it’s believeable.


(theoldghost) #14

Thanks guys from Cycles on I thought I was whistling in the wind. Suddenly it seemed node tress were running off the damn monitor for a simple material. A old Blender friend, Vicky72, simply said I refuse to spend two hours on something the average viewer will never notice. But, suddenly photo realism was the rage. And, to go along with that 500 + graphics cards. Now don’t get me wrong I believe that realism can be the theme of a composition.

But, when you post something and immediately the comments are only about material you have to wonder. I once thought about uploading a image that broke every rule passed down through the ages, composition, value, perspective, viewpoint, and yes even the rule of thirds. Then standby for; ‘Your third rock from the right needs…’

Now this shot will only be on screen for six seconds maybe. I’m actually thinking about a dolly shot towards the door and a fade where suddenly the viewer is inside. I have a shot later where doors actually swing open. But, since this shot is taking 6:30 per frame this might be a option. We all have things we’d like to do when attempting to animate. Left and right of the sidewalk looks nothing like grass. But, at six and a half minutes that is simply a casualty. It seems to me we called it field expediency in the 82nd Airborne.

Anyway once again thanks for the time and comments gentleman. Really refreshing seeing I’m not alone in this wilderness of pseudo realism. (]:-)

(sundialsvc4) #15

Ahh, “photo realism.” There is no​(!) such thing!! :eek:

Every printed or displayed image is a careful contrivance, and completely artificial, engineered to work within the severe limitations of the media with which it is produced. Nothing can begin to replicate the resolving power of the eye, which scans a scene so that the image is constructed in the visual cortex of the brain.

The goal is to produce a convincing result, which the viewer’s eye – also “scanning,” but now scanning just the image – will accept it as plausible. It is not possible by any means now available to produce an accurate imitation of a scene that the brain can absorb as if it were actually there – at least, not until a “holodeck” becomes a physical reality. (And there are people out there right now working on that. But holography has a long way to go yet.)

We do know that the brain’s real-world “scanning of a scene” is directly influenced by storytelling, and by other factors. The viewer will “follow the hero.” Those Q-Tips® were an unimportant crowd. There doesn’t appear to be a hungry tiger in that yonder clump of grass. You can, and should, guide the viewer’s attention where you want it to go, both within one shot and (in a movie) between them. If you establish the presence of “a crowd of spectators,” then maintain their focus on a young hero, they’ll give Q-Tips nary a passing glance, and the movie will ship on-time.

(theoldghost) #16

@sundialsvc4 I think you have something here. But, since the dawn of photography we have somehow learned to accept that as a visual reality. in spite of the limitations you mentioned. And, I have no problem with the perception since photographers record our history and produce art at times.

And, they use to do it in the raw for lack of a better word. Those horrendous shots coming out of Vietnam needed no Photoshop bull shit but maybe a boost in contrast. Now it seems even photography has lost its credibility with the photographs on rag newspapers and sites. I am gladdened by major news agencies drawing a line in the sand. As one fired a photographer several years ago for a Photoshopped version of a town being demolished by bombing.

But, back to 3d programs and attempting to do what a live camera can do. Yes, we all know it can be done but at what cost. And, we have seen amazing example of that in this forum. My daughter, the people photographer,can wrap up a shoot in thirty minutes and pocket five hundred dollars minus gas and wear and tear on the equipment plus editing. Whereas a talented friend of mine from South Africa could hardly begin one of his amazing human creations in that time.

I think I started this reply with a point but evidently a senior moment has rendered that non existent. Oh yeah to be a slave to realism which a camera can clearly do better is not exactly happy Blendering in my book. Then again at my age who knows what the kids will see in their lifetime. Maybe there will be nothing to believe in since our Forth Estate is dying by the day. Our local paper is barely holding on after another layoff. While VFX effects have actors running up walls. @sundialvec4 if there is a point maybe I have lived to long. And, simply don’t need to be on this forum.