Blocking the sun like in Blender

[Elias2019]

Hi,
It seems it's not possible to limit or block the sun in corona to get the effect like this render in blender, that's right?

[romullus]

Hm, just place some geometry outside of view that would partially block the sunlight and cast the shadow on the subject. Just like it works in RL. If you'd block the sun disk itself, that would be something like solar eclipse and it would have totally different effect on the scene lighting than what is visible in your example.

[Elias2019]

Thanks Romullus for always response, yeah I meant blocking the sun with geometry to achieve the cloudy day effect and focusing the sun on specific areas of the scene, I didn't mean the eclipse effect. The problem I am facing in corona is that this method doesn't work very well when there is volume fog in the scene, also big sun size that's necessary for soft shadows makes it worse, there's a lot of light diffusion in the scene which covers the blocking geometries making them practically useless, so it won't be possible to focus or limit the light to a specifc area. If you decrease the sun size it will be easier to get more directionality but the problem is that the shadows will become sharp and that's not desired for an artistic cloudy day soft mood.

Despite Corona, GI is very weak in Blender Cycles so it's really easy to block the sun by placing some geometries in front of it because there's almost no light interactions in Cycles which makes it good for that sun blocking purpose!

[romullus]

You can make shadow softer by moving blocking object farther from the subject. Of course you would also have to make it bigger so that its shadow remains at constant size. Changing sun's size is a cheat, so it's better to avoid that if possible.

Can't say much about volume fog though, since i barely ever use it.

[burnin]

It can be done quite closely to what can be achieved w "Physical Sky & Atmosphere"... but first would be nice to see what your current result looks like.
Here's a quick test w/ latest daily.
 

Edit:
Added "Volume effect"

[Elias2019]

You can make shadow softer by moving blocking object farther from the subject. Of course you would also have to make it bigger so that its shadow remains at constant size. Changing sun's size is a cheat, so it's better to avoid that if possible.

Can't say much about volume fog though, since i barely ever use it.

Thanks for your suggestion, I usually try all this stuff to achieve the desired result but still hard to get what I want. You know my purpose is concept art so I have to manipulate everything I can to see what I had in my mind, this way I have to increase the sun size, maybe if it was possible to do all this with only HDRI and no sun it would be better but in one hand it's hard to find a good HDRI map among 1000's of confusing ones and also the scene loses light directionality without having a direct light source. About volume fog I am using a big box here with a corona volume light applied, that's what we usually do in blender.

It can be done quite closely to what can be achieved w "Physical Sky & Atmosphere"... but first would be nice to see what your current result looks like.
Here's a quick test w/ latest daily.
 

Edit:
Added "Volume effect"

Thanks for your effort Burnin, I really appreciate your time and attention to this issue by making a test scene, I am happy you're familiar with PSA addon, honestly I wanted to make this scene in blender but I am really tired of Cycles as I cannot get those deep light and shadows of corona with it..

Your result is really good, I guess one problem here in my scene is that the sun itself also exists in camera view making it hard to hide undesired issues like blocking geometries (either plane or cube) with the ground. Another problem is that I still get sharp shadows in contact areas between the building and the ground, and that's interesting it's not happening in your scene. Anyways as you mentioned I have attached the scene and its screenshot to see your opinions.

[burnin]

Oh, your reference and stage set are totally different things. Indeed, sun's position and eye/camera's orientation play major roles in 'feel' of the picture. I rather consider thinking photographically. Found it better having more suitable reference(s) or even coming up w/ a mood board than going at it 'blindly'.
As for shadow, any light-interaction starts sharp. It is 'roughness' (medium scattering&density) that visually 'breaks' that rule and creates appearance of soft gradient falloff. As such, 'chiaroscuro' effect can be achieved w/ Cycles (or any other engine). It just takes slightly different shading approach, balancing based on its specs. That's roughly what's about - paying attention to noise - surface detail, which in your case is amiss.

[Elias2019]

Right, while you mention some good points but all that doesn't solve this issue. Most corona or archviz users achieve this effect only in cases the blocking geometries / sun are out of the camera that's why it becomes harder for you to solve I guess, because focusing the light on a specific area in a cloudy day or like the PSA reference I showed doesn't need a photo reference! I guess I should explore some other approaches!

[maru]

Can you explain how this "light blocking" is done in Blender? I am sure we can recreate pretty much the same effect in Corona.

Despite Corona, GI is very weak in Blender Cycles so it's really easy to block the sun by placing some geometries in front of it because there's almost no light interactions in Cycles which makes it good for that sun blocking purpose!

I don't think the "GI is very weak in Blender Cycles" part is true. Even if there is more clamping and less bounces in Cycles by default, I am sure it works in a similar way to Corona.
In Corona, we can make GI "weaker" by lowering the number of bounces (max ray depth) and introducing more GI clamping (max sample intensity).

[burnin]

Right, while you mention some good points but all that doesn't solve this issue. Most corona or archviz users achieve this effect only in cases the blocking geometries / sun are out of the camera that's why it becomes harder for you to solve I guess, because focusing the light on a specific area in a cloudy day or like the PSA reference I showed doesn't need a photo reference! I guess I should explore some other approaches!

As noted, there's basically nothing to solve in the scene you attached (no HDRI map, lack of proper direction)... The way stuff is set,  in hope to achieve the same feel as the reference is simply irrational, which demands to be 'solved' with an illusion, just like in the movies. When natural reality doesn't work, you create your own. Nothing to do with an engine.
Try to provide HDRI and either sketch a concept, lighting plan or find better reference that resembles your 'vision' more (is more inline with what your 'architecture' demands).

[Elias2019]

Irrational.. illusion.. delusion.. movies.. what's the purpose in saying all this? The scene I provided includes HDRI as well, if you are familiar with such scene setups you would probably know that in such cases a PureSky type of HDRI is used just to illuminate the scene, since you are interested in rationality you should probably notice that those big boxes in the scene and their relation with the sun is showing the direction..

This is a technical question side of the art direction not the art direction itself, we are seeking methods of limiting the light source to a specific area and not how they are used according to photo references.

[burnin]

FYI,
I pointed out what needs to be done, strictly in technical terms! 
In scene attached, there's just a path pointing to HDRI map... 
go figure.

Have a nice day.