Author Topic: Juraj's Renderings thread  (Read 312281 times)

2019-06-28, 14:12:59
Reply #645

Alekru

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Juraj Talcik
I read about the textbook(tutorial)
can I see it somewhere, read it?

2019-06-28, 14:29:41
Reply #646

Juraj Talcik

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Juraj Talcik
I read about the textbook(tutorial)
can I see it somewhere, read it?

I am bit confused :- ). But my most recent advice is here, it's more theoretical though:

http://www.cgarchitect.com/2017/12/business-in-arch-viz-vol-10---finding-your-look

But one or two pages ago someone posted some my .pdfs from much older presentation that show a bit more about Sun&Sky and HDRi and to be honest, and while the content is still actual and I am not sure if it's very helpful now.
The article above is better.

Maybe I'll do more practical content but the techniques constantly change, evolve even I learn constantly something different. But the theory is always the same :- ).

Or I can attach those ancient .pdfs (they still mention Vray 2.4 and Corona Alpha 0.7, wow !!) since the information on light is still applicable. But read the article first ! ;- )
The last one is link to VIMEO tutorials by Veronika (they are timelapses in....slovak language, and only 3 of them). That was bit dead end :- )
« Last Edit: 2019-06-28, 14:55:41 by Juraj Talcik »
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2019-06-28, 17:08:12
Reply #647

Alekru

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Thank you very much !
this is useful ,
I saw them, in 1 day I read the whole topic
Could you write more about HDRI and how to change them? and how to identify good HDRI

2019-06-29, 01:36:21
Reply #648

Juraj Talcik

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how to identify good HDRI

Depends on purpose. If you like the result artistically, then the HDRi is good for you in that moment :- ).

But on theoretical level, it's very hard. Easiest is dynamic range: Sunny midday is 16+ stops apart, if the HDRi captures smaller range, it will not create strong enough shadows. So if Sunny midday HDRi creates different intensity of shadows than Corona Sun/Sky, well than it mostly sucks.

But everything else is harder to account for and is more important for automotive visualization. HDRi should never have any contrast applied to original raw linear data, nor any color correction whatsoever. It should look bland. They should also feature neutral white balance if they are to be used with physical camera in CGI app.
99.perc. of HDRi do not pass the above.

More write-up how to change them ? Eh...I am afraid I won't have time for that in near future, that would take too much energy, sorry. But easiest way is to install that HDRStudio or how is that software now called (I never used it).
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2019-06-29, 15:08:03
Reply #649

Alekru

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thank
I only do interior and exterior
cars and the like do not yet need)

2019-07-10, 03:26:55
Reply #650

jnichol4

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Hi Juraj,

I just want to say thanks for all the information you provide in this thread. I am primarily an fstorm user, but I still read your posts quite frequently. I think it's interesting how you seem to be one of the few well known artists that primarily use Sun & Sky for interior visualizations. I believe you mentioned before that even in scenes that are meant to be overcast lighting, and I'm wondering if for those type of scenes, do you just point the sun away from the windows and rely on the skylight, or do you just set the sun to be really big to simulate the not being completely behind the clouds?

2019-07-10, 22:46:26
Reply #651

Juraj Talcik

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You know what, I don't actually have a single well proven solution :- ). I experimented with a lot of concepts, the following is by no means deep analysis, but just inspiration to try stuff:

1) Very soft (0.01-0.1) and large (but not crazy large, so 4-6 size let's say) Sun pointed into scene, natural temperature, or slightly less saturated temperature (-1000 Kelvin). Sky natural, or slightly less saturated (-25perc. ?).
    Simulated diffused Sun behind Clouds pretty ok-ish. Maybe my most used scenario ?

2) Fully physical daylight setup, but the Sun is pointing away from scene, maybe bouncing from opposite facade. This is very interesting scenario because it describes lot of situations in which those scandinavian old apartments are being shot.
The streets are narrow so Sun hits something only partially. But this is technically hard to execute, it requires higher GI intensity cutoff (in Corona, the MSI parameter) and ideally...reflective caustics from opposite glass windows. Well...pure craziness. So it works just partially, but the diffuse Skylight and diffused Sunlight (by spreading and bouncing from opposite facade) creates interesting light.
   This is hard to pull off scenario, I never did it successfully much to my liking. It will also render endlessly regardless of GI, Caustics, or Portal lights. In every renderer.

3) Romullus told me this once: You can set the Sun to 0 and it doesnt' actually deactivate it, as even 0 intensity Sun still modulates the Sky's Intensity and Temperature. It's interesting hack. You can put it further into Desaturation node.
    This should work in multiple renderers because they all use the same Sun/Sky models these days (Hosek&Wilkie).

4) I play around with gamma and haziness parameters to simulate different low-horizon  overcast skies. This can get pretty unrealistic by itself in exterior, but in interior you can never tell what happens outside exactly so that's ok.

5) Some of my overcast scenarios are just pure white color if the architecture did all the work. Like 255/255/255 in Environment Slot and plane to avoid floor lighting :- ). I did this for the patio rooms in Impremta project. Complex architecture defines light perfectly by itself so simplying the source of light can really put focus into architecture as the main light actor. This of course, absolutely doesn't work for penthouse with big glass windows staring into void.

6) I never did the ultra-big sun light (<10) but I've recently seen other studios pull off this trick. You basically act like it's not even sun...but some artifial spotlight reflector, like studio photoshoots for Poliform or BB Italia photoshoots, that kind of style.

- I don't really rely on the the Sun/Sky itself, but it's by basic setup to go to because of flexibility. I can really milk the system to create almost any kind of reality occuring HDRi in terms of interior light. Exteriors are different case altogether, it would not work there. But I really try to play with light modulation with using bounce cards, blockers, soft boxes, barn doors, recently even reflectors & spotlights to get more dramatic effect.
  My setups are once again getting lot more complicated and I feel like there is far too much I don't know and I would really love to have opportunity to shadow some high-end studio photographer (ideally furniture guys).

We shot some HDRi for our own use, and they are brutally calibrated, nothing like on market. But.. I was never quite happy and successful with the approach of "drop realistic light into scene and watch wonders happen". It works for exterior scenes that are partial towards such approach (curvy surfaces, reflective materials, lot of glass), it works amazingly for studio setups and automotive renderings, but I've found the results in interiors are identical to what I can get with Sun/Sky, but I lack the freedom to changes stuff as easily.
Other artists seems to get fantastic results though...so this might be just my deficiency. But someone here recently summed my feelings and experiences super well with story like "I spend whole night trying 100 Hdris and then go back to Sun/Sky". And that was me so very often...

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2019-07-15, 17:51:45
Reply #652

jnichol4

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Man, I really appreciate you taking the time for such a thought out response. This gives me so much to think about!

I had a feeling there was not a one size fits all solution (if there was, most of us would be out of work, right?), but your different approaches are still really insightful. Your first one you mention, is essentially what I am experimenting with in Fstorm right now, and I am getting decent results, but I think I am still lacking in my tonemapping skills (either way I won't get into Fstorm too much).

I am in a similar boat, where I find myself cycling through different HDRIs so much, and always thinking there is something I wish that was different about each one. I remember in your recent article how mentioned to not be afraid of editing HDRIs, and I have done that and had some great success, but I found myself ending up with so many different versions of each HDRI, and needing to make slight tweaks each time, then I stumbled on this thread and saw how much success you are having with Sun & Sky, and while I realize there is so much more to your work than just the lighting solution, but I wanted to try my hand at using Sun & Sky and see what type of results I could get, since I do love the flexibility.

I also wish for the same thing as you! I am beginning to work more with furniture studios, and am really hoping to get a chance to shadow their photographers one day.

Anyways, thanks again for the great post. I will continue my experimentation. :)

2019-08-14, 16:02:05
Reply #653

Razzow

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You know what, I don't actually have a single well proven solution :- ). I experimented with a lot of concepts, the following is by no means deep analysis, but just inspiration to try stuff:

1) Very soft (0.01-0.1) and large (but not crazy large, so 4-6 size let's say) Sun pointed into scene, natural temperature, or slightly less saturated temperature (-1000 Kelvin). Sky natural, or slightly less saturated (-25perc. ?).
    Simulated diffused Sun behind Clouds pretty ok-ish. Maybe my most used scenario ?

2) Fully physical daylight setup, but the Sun is pointing away from scene, maybe bouncing from opposite facade. This is very interesting scenario because it describes lot of situations in which those scandinavian old apartments are being shot.
The streets are narrow so Sun hits something only partially. But this is technically hard to execute, it requires higher GI intensity cutoff (in Corona, the MSI parameter) and ideally...reflective caustics from opposite glass windows. Well...pure craziness. So it works just partially, but the diffuse Skylight and diffused Sunlight (by spreading and bouncing from opposite facade) creates interesting light.
   This is hard to pull off scenario, I never did it successfully much to my liking. It will also render endlessly regardless of GI, Caustics, or Portal lights. In every renderer.

3) Romullus told me this once: You can set the Sun to 0 and it doesnt' actually deactivate it, as even 0 intensity Sun still modulates the Sky's Intensity and Temperature. It's interesting hack. You can put it further into Desaturation node.
    This should work in multiple renderers because they all use the same Sun/Sky models these days (Hosek&Wilkie).

4) I play around with gamma and haziness parameters to simulate different low-horizon  overcast skies. This can get pretty unrealistic by itself in exterior, but in interior you can never tell what happens outside exactly so that's ok.

5) Some of my overcast scenarios are just pure white color if the architecture did all the work. Like 255/255/255 in Environment Slot and plane to avoid floor lighting :- ). I did this for the patio rooms in Impremta project. Complex architecture defines light perfectly by itself so simplying the source of light can really put focus into architecture as the main light actor. This of course, absolutely doesn't work for penthouse with big glass windows staring into void.

6) I never did the ultra-big sun light (<10) but I've recently seen other studios pull off this trick. You basically act like it's not even sun...but some artifial spotlight reflector, like studio photoshoots for Poliform or BB Italia photoshoots, that kind of style.

- I don't really rely on the the Sun/Sky itself, but it's by basic setup to go to because of flexibility. I can really milk the system to create almost any kind of reality occuring HDRi in terms of interior light. Exteriors are different case altogether, it would not work there. But I really try to play with light modulation with using bounce cards, blockers, soft boxes, barn doors, recently even reflectors & spotlights to get more dramatic effect.
  My setups are once again getting lot more complicated and I feel like there is far too much I don't know and I would really love to have opportunity to shadow some high-end studio photographer (ideally furniture guys).

We shot some HDRi for our own use, and they are brutally calibrated, nothing like on market. But.. I was never quite happy and successful with the approach of "drop realistic light into scene and watch wonders happen". It works for exterior scenes that are partial towards such approach (curvy surfaces, reflective materials, lot of glass), it works amazingly for studio setups and automotive renderings, but I've found the results in interiors are identical to what I can get with Sun/Sky, but I lack the freedom to changes stuff as easily.
Other artists seems to get fantastic results though...so this might be just my deficiency. But someone here recently summed my feelings and experiences super well with story like "I spend whole night trying 100 Hdris and then go back to Sun/Sky". And that was me so very often...

Really well written, thanks for sharing those thoughts with us. Do you have any good tip on accually good HDRIS for exterior?

2019-08-14, 17:29:43
Reply #654

Juraj Talcik

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Nope, I don't test these things :- ).

People like the HDRiHaven because it's free and the guy mostly knows what he is doing. But I saw his tutorial and he just deliberately desatured yellow before processing I almost got heart attack :- ) Real HDRi cannot have any post-production of source files, they need to be absolutely linearized.

One tip how to spot good HDRI outside of testing dynamic range: It has to look like shit. Overburn and washed out. Linear files have no contrast, no deep blacks. So if HDRi looks "nice", the person probably kept some default camera profile from raw converter instead of full linearizing. The HDRi will still make nice light in artistic way, but not accurate, real-world light from said HDRi capture.
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2019-08-15, 07:29:26
Reply #655

Razzow

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Thank you, will keep that in mind!

2019-09-10, 16:47:32
Reply #656

cjwidd

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Thank you kindly Melviso. Here is small sneak peek. From cold London, to sunny Mallorca ! And there will be new caustics...subtle, but where they would belong.



Really love the floor tiles in this image, are they geo, displacement, normal map, or all of the above?

2019-09-10, 17:16:47
Reply #657

Juraj Talcik

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Last one is correct, all of it :- ) Here is reasoning behind:

Total base is floorgen tiles but with zero grout or extrude. It gives me nice random UVWs.
Displacement on top is used to give it "rough" detail, so the edges and some structure, but mostly the edges. Chamfered edges never look as good as more complex displaced ones.
Normal map is the usual micro-detail that displacement (even tiny one under <1px) would never create.

If you need some nice base displacements for tiles look at TexturesCom PBR section and SubstanceSource.
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2019-09-17, 17:33:10
Reply #658

cjwidd

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Juraj, I apologize if you have addressed this question elsewhere, but what is your approach to material libraries? For example, there are many ways to acquire high quality textures (e.g. Quixel, Substance, Friendly Shade, Siger Studio, etc.). In your work, do you rely on material libraries, or have you constructed a custom material library over the years and that suits your needs?

2019-09-18, 18:22:23
Reply #659

Juraj Talcik

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Juraj, I apologize if you have addressed this question elsewhere, but what is your approach to material libraries? For example, there are many ways to acquire high quality textures (e.g. Quixel, Substance, Friendly Shade, Siger Studio, etc.). In your work, do you rely on material libraries, or have you constructed a custom material library over the years and that suits your needs?

Even materials I created last year is already a material I dislike, or isn't up to my idea of quality, so I didn't built any reasonable library ;- ).

I would like to start with one but I would like a better base, I don't like 'CoronaMTL', I don't want to spend hundreds of hours having library full of fallofs in diffuse (instead of 'Sheen' parameter), all metals as multilayered mess when all I need is coating inside the material,etc..
For Archviz, good material is very simple, and is fully driven by high-quality textures, so they're easy and quick to build each time.

But when we'll finally get good PBR Material, I'll make more cohesive library and it will be inside Connecter. Right now I use SigerCMPP for material storage, but it's really quite slow, and the thumbnails are only 200px when small, that's too tiny for my 4K monitor.
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