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Messages - houska

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[C4D] General Discussion / Re: Layered material
« on: 2020-02-12, 15:22:48 »

I'd first suggest to try to use the C4D's native material stacking (see the attached image), otherwise if you really need the Layer shader, I'd suggest to use the Effects->Projector shader to modify the projection of the individual layers

Edit: Sorry, I thought you were talking about the Layer shader... With Layered material, it's currently impossible to modify the projection of the individual materials... You can always try the native stacking though!

So is there a physically correct way to set up a light for accurate emission based on the datasheet of a light fitting? Would you need to make a corona light that is the size of a bulb filament?

I'd say your best bet is probably using a light with .ies profile. Modelling a bulb filament doesn't make much sense unless you're planning to do shots very close up.

And if you'd like me to be more specific, the formulas are following:

[Lumens] = [watts/(sr*m2)] * radioToPhoto * π * SurfaceArea
[Candelas] = [watts/(sr*m2)] * radioToPhoto * SurfaceArea
[Lux] = [watts/(sr*m2)] * radioToPhoto * π

Radio to photo is a conversion factor between radiometric and photometric units (this is where the 555 nm are taken into account)

In the intensity drop down when using a corona light you can set what units you want to use.
Are these correct conversions when changing the units?

Actually, yes, these conversions are correct, but they only take into account the limited data that can be inferred without doing any super-complicated and lengthy calculations.

In particular, if I recall correctly, they calculate with the light object's surface volume, they presume lambertian light emission distribution and they assume that the light has a wavelength of 555nm, where the light sensitivity of human light sensitive cells is the highest.

[C4D] I need help! / Re: sky background
« on: 2020-02-05, 15:16:25 »
If you use sky + Corona Sky, they will be added together. That's why the first picture is so bright. So maybe to fix that, you should use Corona compositing tag with everything except "seen by GI" and "cast shadows" disabled?

 I don't wee any issues otherwise.

[C4D] I need help! / Re: sky background
« on: 2020-02-05, 11:06:47 »
Hi, this is strange, I just tried it and have the same result with (left) Corona Light material in environment override and (right) HDRI bitmap placed into the Shader/HDRI slot in the Corona Sky. See the attached picture.

What HDRI are you using? Maybe the issues are related to that specific file (especially the fireflies).

Otherwise, both options - env. override and Corona Sky - should be equivalent.

Hello, you are the second person who reported this, so it's probably happening more often. We'll think about using some kind of a warning when you're sending the render into the render queue. But there is still an issue with render regions saved in a file that you send to render farms. There won't be any warning in that case of course...

Thanks for the file upload, Wolfgang! We will check it out and let you know what we found out.

Thanks for the explanation! It all makes sense now.

I didn't realize that when saving to .tif, each pass has its own .tif file. And Beauty pass cannot be turned off, so it always gets overwritten even though you don't render it, because the "Masks only" option is turned on...

Yeah, that makes sense to me. We'll see what can be done. Thanks for the patience! ;-)

It does render only masks. But then, when you want it to save into a tif, it does exactly that.

Just to make sure - you have output file specified in the "Save" section of the render settings, right?

Well, if I understand your request correctly, it makes total sense to me. Your files get overwritten, because you specified them to be overwritten in the "Save" section of the render settings. Whether you only render masks or whether you do normal shading doesn't have anything to do with it.

If I am reading this incorrectly, please correct me.

[C4D] Feature Requests / Re: Projector Shader in Corona
« on: 2020-01-29, 20:33:26 »
Hello Cestmir, I am in a middle of project where I need projector shader to function.
Could you tell me if it will be updated via a hotfix within lets say couple of days, else I need to rebuild the project in different renderer :)

Hi Daniel, we found and fixed a bug already, which was causing some mapping issues! I am not sure if this is the bug that you described, but we would like to release that fix together with other small things as a daily soon. I cannot tell you when that will be, unfortunately :-( I'd say there's a 75% chance it will be on Friday, but I cannot make promises in this regard at the moment.

Besides ... the discussion reminded me of the Vray material window ...

Yeah, don't get me wrong, I'm not trying to be smart or anything, but this is the first line of the entry on Lumen from Wikipedia (emphasis added):
"The lumen (symbol: lm) is the SI derived unit of luminous flux, a measure of the total quantity of visible light emitted by a source per unit of time."

So how in the world can a material with a total luminous flux of 1500 Lumen work?? Will it spawn a different material per each object it's assigned to, based on the object's size? Or will it calculate its intensity according to a reference surface (let's say 1m^2)? In both cases, I can imagine a lot of surprised (and angry) users :-)

Edit: As I said - watts per steradian and meter squared - sure! Candela - why not?! But I'm not convinced it would make physical sense to have Lumens...

Yes, and in the Corona Light Material, it's simply nonsense to have Lumens, as pointed out earlier ;-)

[C4D] Bug Reporting / Re: V5 Render regions
« on: 2020-01-28, 17:19:09 »
Hi mte,

we fixed some issues with render regions in V5 Hotfix1. Can you please confirm that your issues were fixed with that release?

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