mesh emitter only work with Reinhard tonemapping?

[afecelis]

Hi guys,

I'm retaking this nice render engine and I'm trying to get a grip of all of its options. I'm using Indigo Renderer 3.8.29 and blendigo 3.8.25 and most of the things are quite clear and the blender exporter does a great job, however I'm running into the following issue:
-On a simple Cornell box text scene, I'm using a blackbody mesh emitter, when using reinhard tonemapping I get the following result:


However, when I use camera or linear I get very weird results:



Is this normal? I read somewhere that it was better to use camera/linear tonemapping, but in this case it seems only Reinhard is working

Also, I'd like to have mesh emitters on the ceiling of this scene (illuminated with an exr env map)

But whenever I use the emitter material, the env map/sunsky background turns completely black. I've seen some amazing renders in the forums and the galleries in which they have both a sunsky/env map combined with mesh emitters/ies lights. How do you achieve this in Indigo?

thanks in advance for any help,
regards,
Alvaro

Ps.
Here's the scene in another renderer:

In it I can mix sun light/hdr environment maps + emitters. Also, I can leave the background as alpha and the glass renders crystal clear. In indigo the glass renders quite noisy and when I add the background in postpro you can barely see it. How long do you have to leave the scene rendering for the glass to render clean?

[Polinalkrimizei]

Hey afecelis, welcome back

As for your Cornell Box Scene: The issue is just "too much light", simply lower the EV to e.g. -5 (with camera tonemapping). With Reinhard as tonemapping, Reinhard does the tonemapping for your, it is always going to look pretty balanced, but also kind of dull.
As for your other issue, you need to balance the intensity of the light sources by yourself, works directly in blender. I guess you used the standard values (blendigo) for your emitters? Then try to set the gain of the env-map higher (10*X in the light settings, set X to 4 or 5 as a start and go much higher if it doesn't show any effect).
If the intensity of the hdri is too low compared top the emitters, it will not only render black/too dark, but also will get almost no processing power = areas supposed to be lit by the anv map will not get clear.
Play with the numbers to get the balance right, and use the light layers within indigo for fine tuning. But interior renders with multiple light sources WILL take some time nevertheless, be sure to check the forum about exit portals, arch glass, and the intensity of your white's

And please post results!

[Zalevskiy]

Hi guys,

I'm retaking this nice render engine and I'm trying to get a grip of all of its options. I'm using Indigo Renderer 3.8.29 and blendigo 3.8.25 and most of the things are quite clear and the blender exporter does a great job, however I'm running into the following issue:
-On a simple Cornell box text scene, I'm using a blackbody mesh emitter, when using reinhard tonemapping I get the following result:


However, when I use camera or linear I get very weird results:



Is this normal? I read somewhere that it was better to use camera/linear tonemapping, but in this case it seems only Reinhard is working

Also, I'd like to have mesh emitters on the ceiling of this scene (illuminated with an exr env map)

But whenever I use the emitter material, the env map/sunsky background turns completely black. I've seen some amazing renders in the forums and the galleries in which they have both a sunsky/env map combined with mesh emitters/ies lights. How do you achieve this in Indigo?

thanks in advance for any help,
regards,
Alvaro

Ps.
Here's the scene in another renderer:

In it I can mix sun light/hdr environment maps + emitters. Also, I can leave the background as alpha and the glass renders crystal clear. In indigo the glass renders quite noisy and when I add the background in postpro you can barely see it. How long do you have to leave the scene rendering for the glass to render clean?

my indigo 3.8.26 test

[afecelis]

Whoah! thanks a lot Polinalkrimizei and Zalevskiy
I'ts great to come back after so long and still feel the warmth of its community.

Thank you for the very detailed explanations. I'll try all those tips out and post my results. Where can I find more info on light layers and how to implement them within blender's options?

regards,
Alvaro

[afecelis]

OK Guys, some progress on mesh emitters and camera tonemapping. Following your recommendations, I was able to get it to work by changing the EV adjust value and lowering the iso, combined with lowering the gain of the light layer for the emitter:


But I haven't been so lucky with environment maps (exr) (or the sunsky). No matter how high I set it, it still is black. I have cranked its light layer gain value to the max as well as the gain exponent in blender, but nothing changes. Only when I set the mesh emitter value to zero the envmap appears and lights up the scene. I don't know if it's the exr image I'm using. I'm going to try with a different one and let you guys know how things go. Light layers are great BTW!

regards,
Alvaro

[Oscar J]

To avoid noisy glass - use the arch glass tick box.

*See attachments* The blackbody emitters render fine with very small gain values for the lights. I think this might be due to unnaturally big blackbody emitters - in real life, blackbody emitting objects are usually very small, like the wolfram thread in a light bulb. But in your scene you have a rather big surface giving off the same intensity per area unit, which means a LOT of light.

The way I usually do it, though I'm no expert on interior rendering, is rendering with just a white RGB emission (which is much more flexible to change the power of), and then select blackbody in the light layers setting to adjust the warmth of the lights.

[afecelis]

Thanks a lot Oscar

Could you please share your .blend file? I'd like to take a closer look at your settings. Don't worry about the exr file, I'll replace it with one here.

regards,
Alvaro

ps. One last question. I'm using the arch glass material option for the windows, but I wanted to know if the mesh needs to be a simple plane or if it can have real life thickness (i.e. in my scene the glass has 3mm).

[Oscar J]

There ya go.

Your windows look really weird - for foreground alpha renders I'd suggest using .png if you aren't already .

[afecelis]

Excellent! thank you! I'm going to check it right away.

Indeed the glass looks weird. I'm rendering my image as png so I can have an alpha background to replace but this is how the glass looks when I insert a background:



And you can't see the wall outside the balcony (as in the other renderer sample image).

whewh! lots of tests to run, lots of learning ahead! Thanks for all the help!

regards,
Alvaro

ps. Edit: In this latest Indigo Image I rendered 2 scenes, 1 with only mesh emitters and the other one with sunsky and mixed them in Gimp, hence the emitters on the ceiling, lol

[Oscar J]

You're welcome.

I think the reflections should look cleaner if you simply let it render longer. Also from my experience the windows get the right transparency with longer render times as well. If you still feel that there are too much reflections when compositing, I suppose lowering the IOR of the glass should help - or reducing the alpha opacity in Photoshop using a Material ID pass.

Are you using exit portals for the windows? Glare have been working on an exit portal system that should make objects outside of them visible, but in the meantime the workaround is to model an exit portal box around all of the geometry that you want visible.

[afecelis]

Yup, I'm using exit portals, but they're simple planes covering the area of the window with the normals pointing inside the room. Where can I find info on Glare's portal system? And what do you mean by the workaround of modeling an exit portal box around? You mean outside of the window portals, wrap the models I want visible outside with exit portal boxes? hmmmmmm I hope portals work as they should some day, lol What about rendering without portals? Will it make the geometry outside visible? Too dark inside, or impossible to render? I read somewhere in the forums that that's the reason why someone renders his scenes without portals.

OK, I just tested your blend file and it works perfect. I tried implementing the same setting as yours in my scene but when I render it doesn't work...arggghhhh! Hulk angry! Hulk destroys! pant...pant... hahahahaha.

I'm attaching my scene, all there's to be done is to replace the exr file. COuld you please take a look at my scene?

regards,
Alvaro

Edit: I think I found my mistake, I forgot to increase the gain of the envmap *8, I'm going to try it! (fingers crossed!)

[afecelis]

It works!!!!!! thank you, thank you, thank you all!


However, I removed the portals and the windows with the glass material just to make sure things were working ok. Now more tests, gotta make some more coffee.... yawwwwwnnnnnn

ps. And here's the Cornell box:

[afecelis]

OK, progress... so far:


Achievements (thanks to the help of all of you):
-I was able to use mesh emitters + sunsky
-I learned how to separate each of them in light layers to modify their intensity by separate
-I learned how to change the emitter's temperature/color
-Placed my exit portals better (now you can see the walls outside the room and the rail)
-Got a lot more familiar with both the blendigo exporter options and the options in the Indigo application

Todo/learn:
-Better camera options for DOF /vignetting, etc
-Find the perfect amount of rendering samples to get a cleaner image (glass still needs more time to be clear)
-Learn about instancing
-Learn about alpha materials for leaves
-Learn to use IES lights
-Learn about animating with Indigo
-A lot of other stuff. Indigo is an immense universe of options and learning how to tweak them properly represents the succes of your image. Still a long way to go

Notes:
-I was very impressed by the reflection on the ceiling bouncing from the glass table at the living room (in contact with direct sunlight).
-It's a shame Bidir+MLT, and the other rendering algorithms, don't work on Cuda. Are they planned to be implemented? Path tracing+Cuda doesn't allow sunlight to cross the glass material It also feels weird to stress the processor so much and for so long when having such computational power nowadays available on GPUs, besides, trying to put up a double-processor PC (or putting up another computer for network rendering) is more expensive than getting a good Nvidia card.

Thanks to all of you again , I'll keep on posting any process and any questions here. Comments are welcome.

regards,
Alvaro

[afecelis]

Next attempt:

Question, how do you reduce the bump map intensity in blender?

[Polinalkrimizei]

Materials panel => Material Bump Map => (B) Scale is the height of the bump map in meters