Morning Mist

[Hannes]

(see post before!!)
Actually I just thought, all this may not work in your scene, since you have water. And even though the hemisphere is set to invisible, it will reflect in the water.
Unchecking "visible to other rays" (also in the rendering tab of the object) also kills the additional lighting!

Too bad!!!!!!! However, it works in "dry" scenes.

[WAS]

OK, I created a scene somehow similar to yours. Here is the result.
As expected the original render is quite dark in the forest area.
The second sun/no shadows image rendered the fastest and looks terrible (to my taste). The second sun w. (soft) shadows image took the longest to render. The trees look quite nice, but the shadows on the floor don't fit to the "real sun".

For the other images I loaded the hemisphere that I already mentioned. I attached it here. It has a radius of 50 meters. You can scale it like desired. I think, the hemisphere only has to cover the foreground trees in your case.
Paul, you asked me how to make it invisible and so on. Here are the instructions: after you have imported it, go to the object's "Rendering" tab, uncheck "Cast shadows", and set "Render" to "invisible". No need to care about the normals.
I used a luminosity of 1, which is the value in the TGO. Do some tests in your scene, and use a value that looks best.

If you use this method, you may have to increase the AA. The indirect lighting tends to render a bit more noisy.

I hope, this helps. Actually it was great fun to make this comparison.

Yeah I've always liked luminosity in place of a second sun. The sun interacts with too many other functions, like transparency of leaves, even when the strength is super low, it gets added to calculations there.

I'd imagine if you were using this method for overcast, with water, it may work.

[Dune]

Actually, it shouldn't be that you have to take steps like these to get some light in canopies and such. Perhaps there should be a setting (changed) in the Path tracer itself, so more light is transmitted through dark areas. Like the GI in RT.

I agree with Hannes once more, btw., but I will still use an extra sun where needed.

[pclavett]

Well guys, this discussion got really interesting ! I love Hannes' idea of the luminous sphere and thank him for sharing it. His pictures of the examples are great and indeed, the luminous sphere appears to give great results. I inserted the sphere and adjusted its size to fit my project, did a few cropped trial renders and came up with a value of 0.85 for the luminosity, that seemed to fit my needs. The water was also affected very positively and had to do some tweaks to my rivershores and riverbed to make it look nicer. I started the final render and then read Hannes comments about the possible problem with the reflections in the water ! By then the render was under way and knew it would take hours to see the water..... so simply went to bed ! This morning, the render is done, and everything looks pretty good. I do not see artifacts in the reflections but note that the sphere extended beyond the bend in the river...... so maybe was just lucky. Also, I had toned down the reflective tab for the water..... so as to better see the riverbed. During that time, the 2 suns render was going on my MAC and also came out during the night. As far as the vegetation, both seem acceptable with only minor differences. The second sun was at a value in strength of 0.25. The water, though, is way better in the luminous sphere version. The river shore is also better in the luminous sphere version, but I did tweak the shaders and added one of my Fakerock Complex...... so that comparison would not be totally fair. I think, that the luminous sphere wins. I do not see reflection artifacts that are disturbing, and just the foreground river appearance seems to be worth it ! The images have not been photoshoped at all exdcept for reduction in size and conversion to JPEG. I will take the time to tweak them in Photoshop later and post them and see which one wins, think it will still be the sphere, because of the water ! Agree with Ulco that it would be nice for the path tracer to take into account some of the GI illumination..... if that is possible, computing-wise ! Again, your help is appreciated and I must say that I have learned a lot of things with this one ! Have a great Sunday all ! Paul

[Dune]

I agree with you here; the luminous dome absolutely wins (light on trees in front is wonderful), but the stones also add a great deal of perfection. I love this render! Did you check out render times of both (extra sun and lumnous dome)? They can be found in automatic saved renders titles. I wonder how much they differ in your case.

[pclavett]

Sorry Ulco, did not check the times but they were less than my sleep time (6H, 4000PX, Detail 1, AA 9) for both and difficult to compare as one done one my old MACPRO and the other on my new PC..... think they were relatively similar though ! The rocks really improve the shore and the perfect light on them gives them credit ! I could not figure out the comment the Hannes did on the reflections with the dome as it did not seem to impact mine..... so I did an experiment ! I did a whole in the ground with water, put the dome over and did a few renders. The setup with no sphere is "SPHERE OFF". You can see with the setup with the sphere on and visible in "SPHERE ON". I put a reddish tint to see the effect on the ground and you can see the reddish tint on the soil ! Then I put the settings as I was instructed for making the illumination, sphere invisible, visible to other rays on, no shadow..... and you get "SPHERE INVISIBLE". Hannes was right.... we get the illuminated soil but the reflection is that of the dome, the mountain being hidden. When you turn off the "VISIBLE TO OTHER RAYS", then the mountain reflection comes back but the soil is no longer illuminated....defeating the purpose of the dome..... as in image "OTHER RAYS OFF" ! Then I increased the dome size by 100, getting the dome beyond the mountain..... and got "VERY BIG DOME". The "SCREENSHOT" show that the dome extends beyond the mountain ! Now the mountain reflection is back and the illumination is still on.... but includes also the mountain being illuminated. Still, it seems that you can keep the purpose and the water reflections by extending the dome beyond whatever you need for the reflections..... so in a way, you can bypass the limitation. Do not know if having such a massive dome decreases the effect on the shadowy areas or whether it screws up the render times though ! So it seems that the reason that my reflections were not affected was that the dome extended beyond what was needed to get them. If I now look at my image, there are minimal discrepancies in the distant middle reflections but it shows less because of all the mist issues. This exercise was worthwhile as I again learned a few things. Again, all your feedback appreciated ! Paul  PS: As an afterthought.....might take a very very large dome to include your clouds in the reflections !!!

[Hannes]

Great!!!!! I really like how this came out. The stones at the shoreline look beautiful!
I think all this would be easier, if we would have the possibility to just increase the environment light's multiplier while we're using the path tracer, like we can using the legacy renderer. I once had a discussion (I don't remember if it was with Matt or with Oshyan) about exactly this. I think it was Matt, who said, the path tracer represents a real lighting situation, and increasing the exposure would be the realistic way to brighten up a dark forest scene for example.
But why not having the possibility to cheat a bit, knowing it's not physically correct?

[Hannes]

I did another try with a second sun. The only way to make the false shadows look OK was to use a very large soft shadows diameter (200). Takes longer to render than the hemisphere solution.

[pclavett]

I would imagine that those soft shadows are costly on rendering time ! This thread has taught me a lot of things ! Think that each project requires a different solution in terms of shaded areas and your luminous hemisphere solution is certainly a very good one......if water reflections are not an issue. As noted above in my simulation, there are ways to bring back mountains and surfaces by pushing the hemisphere further than the content that will be part of the reflection......but there is probably no way that the sky can be brought back in those reflections if you use the hemisphere. Even if you pushed the sphere into space, you probably only override the background node. On my images, you note that the one where the mountain reflection is now seen that the reflections of the sky are not blue but whitish ! Again, thanks for all your time and efforts ! Paul

[Hannes]

It was my pleasure!!

[Dune]

You could try a luminous plane hovering above the forest. Light wouldn't be as 'spherical' GI-like, but you won't see it reflected (if placed well). I do that sometimes, as said before.

[pclavett]

All good suggestions my friends ! I did Photoshop the last render a bit and got a bit more detail in the shadows. I also rendered another with the sun a bit more right so as to hit the left foreground.....but the trials with the PT again had very dark woods and doing the regular renderer with GI gave vegetation that were far from the beauty of the PT. I had of course that huge water expanse to deal wit the luminous sphere....and trial renders showed indeed the reflections of the sky as a bland white expanse. What I did then was rotate the sphere so as to create an amphitheater-like structure around the back of the camera with its border extending frontward but not to a point to be visible to the camera (by making it visible for placement). Then the trial renders showed better shadow areas and reflection appropriate. You can now see some of the blue sky and most notably the sun in the reflections. The water here was given a 50% reflective strength so as to permit seeing the riverbed more. Using a plane as Ulco has said would likely produce similar results but...... as he said as well, it would be nice if you could keep the huge benefit of the PT for objects and get some light adjustment capabilities in the shadowy areas...... but as my mother used to tell me all the time..... "...maybe you cannot get everything you want my boy!". The last one was included in a 4000PX format if you wish to examine the detail further ! Now on to another project and see you again soon !

[Hannes]

Gorgeous!!!!! What a beauty! I like the first one better. Somehow the lighting looks more interesting to me.

What I did then was rotate the sphere so as to create an amphitheater-like structure around the back of the camera with its border extending frontward but not to a point to be visible to the camera (by making it visible for placement)

Now, that's a great idea!!!!!

[Dune]

Left one is great indeed! But how do you rotate a sphere to get an amphitheathre-like structure. I can't 'see' it in front of me. Another way would be to make some sort of soft ramp from a plane, bending overhead from behind camera.

[Hannes]

As far as I understood he took the hollow hemisphere and placed it like a baseball cap above the camera slightly rotated upwards. I hope this makes sense.