Bump...

[Nikola]

Bottom line is corona bump is terrible and has always been in C4D, I dont think its a problem in max otherwise we would have heard about it. I'm not a coder but there seems to be a stumbling block on this one. For me its coronas Achilles heal. Toms checkerboard example is a good one to show the poor bump performance. Perhaps the new bump converter shader coming in the next beta might help though? Quite often it helps to blur the map slightly in the shader - you get a more pronounced effect at the expense of sharpness.

I love corona but I have to admit the vray bump is undeniably better and much more reliable across its strength range and where using shaders or bitmaps.

Hi Rob,

There is still probably misunderstanding from our side what is your expectation about how the bump mapping should work. Could I ask you to create two simple scenes with one cube using the same setup (using the same bump map) first using VRay bump mapping and second using Corona bump mapping so we can compare the renders? We would like to improve bump mapping because it looks that current results are somehow counterintuitive but to be able to do it we need to know what is the desired result. Thank you

Nikola

[Rhodesy]

Thanks for looking in to this again Nikola. I have put a link in to a drop box zip with the file and oak texture so hopefully that works.

Please see the attached images. I have just used the respective material preview ball scenes with a semi gloss grey diffuse base so we can just see the bump effect but there will be some slight calibration variation in hue. Also I have use the vray default of 1cm strength and picked 58% for the corona one as a sort of half way strength. Making it more or less doesnt seem to help / make much difference.

As a side note I personally prefer the cm scale range rather than a percentage - at least you can visualise roughly the amount you are dialing in in CMs, where as percentage is quite arbitrary especially if we can go over 100%. I wonder if there could be some calibration for this between black and white in corona? 

So regarding the Oak bump images; I have just made a straight desaturated with enhanced curves jpeg of an oak texture and loaded that in to the bump slot in both mat editors. Straight out of the box you can see vray picks up every strand of wood grain and you get a real sense of a rough wood surface. There is a strong shading artifact in the preview ball but I think that is the way it is set up/lit. As for the corona one we just get a high frequency noise that doesnt represent the wood grain. If I ramp up the strength to 500% we still get this strange high frequency noise, but if i blur it by 0.5% magically we then get to see the wood grain but we have sacrificed a bit of texture detail in the process and I still prefer the detail and feel of the vray one as it is more fiberous where the corona one smooths out the subtle threads due to the bluring. Also we shouldnt need to blur this texture to see it!

Moving on to the checker. I have used the same strengths as the previous test (1cm and 58%) This is a hard test case as we are going from pure black to white in a pixel width. But vray has a reasonable stab at it and there is a bit of a surface there. Corona fails to create a surface. If I then blur the checker for vray giving a ramp between colours you get a good relief and you can feel that checker surface over the ball. Do the same with corona and its an even more noticable painted on strange cross pattern.

So hopefully this gives a clear guide on why i think vray is definately better at bump and works well with hardly any tinkering. Corona as it stands is always a battle to get the bump to work and work well with the right strength. I hope its a simple fix or a scan down the chaos group code now Im guessing you have access to it - although sadly not the vrayforc4d code. Thanks again and will always chose corona over vray regardless but it would be nice to get this fixed once and for all. Cheers.

https://www.dropbox.com/s/3jofdjmnbg4rf58/corona%20bump.zip?dl=0

[mrittman]

Agreed. The Vray stuff does such a good job with bump maps. Hoping maybe they can bring some of that into Corona.

[meidenberg]

I'm also getting this result (Beta 1), its like the bump is expaning to the sides instead of upwards.

[Rhodesy]

Agreed. The Vray stuff does such a good job with bump maps. Hoping maybe they can bring some of that into Corona.

Annoyingly vrayforc4d is the only plugin not developed by chaos group so all that specific c4d knowledge is lost.

[houska]

Annoyingly vrayforc4d is the only plugin not developed by chaos group so all that specific c4d knowledge is lost.

This is rather a core thing. So we can merilly ask VRay about their bump-mapping solution. The thing is it will need to be implemented in the Corona core too (i.e. not in the C4D plugin).

[Rhodesy]

Thanks for shedding some light on this Houska. How does the Max version get such results out of the core? I thought it was just how C4D was connecting with the core that was the problem. The C4D one is really bad /  unpredictable.

I wish Corona had taken the approach of a universal node editor that worked with every base app, so the only thing the base app was doing was handling the mapping. I can't see a downside to this if the corona material / shader system was comprehensive enough. We are getting those advanced features as it is with the Max version; inbuilt triplanar and UV randomiser etc. It seems the wheel has to be reinvented with every plugin and I'm not sure why this is necessary? Perhaps this is to do with procedural shaders but could this not be handled in the corona core?

PS any update on when we will get rounded edges back?

[houska]

Thanks for shedding some light on this Houska. How does the Max version get such results out of the core? I thought it was just how C4D was connecting with the core that was the problem. The C4D one is really bad /  unpredictable.

I wish Corona had taken the approach of a universal node editor that worked with every base app, so the only thing the base app was doing was handling the mapping. I can't see a downside to this if the corona material / shader system was comprehensive enough. We are getting those advanced features as it is with the Max version; inbuilt triplanar and UV randomiser etc. It seems the wheel has to be reinvented with every plugin and I'm not sure why this is necessary? Perhaps this is to do with procedural shaders but could this not be handled in the corona core?

PS any update on when we will get rounded edges back?

Nikola would tell you more about the bump since he's the one playing with it, but he's currently out of office. But he found out there are differences between VRay and Max too.

As for the node-based approach, I wish things were that simple :-)

It's not possible, because you can't have a core that will be so universal, that you'll not have to do anything (besides the mapping) in every possible base app. And remember it's not only about materials and shaders. Hooking into the app's UI can sometimes be tricky too, plus you have to map the scene with its geometry. And don't forget the IR, which is almost impossible to do in the current C4D's API :-)

[vlado]

This is rather a core thing. So we can merilly ask VRay about their bump-mapping solution. The thing is it will need to be implemented in the Corona core too (i.e. not in the C4D plugin).

Yup, the bump mapping is imlemented in V-Ray core. Most of the code is actually included with the public V-Ray SDK.

Best regards,
Vlado

[Rhodesy]

Thanks for chiming in Vlado. So would this mean a full corona core rewrite across all platforms for the bump mapping part of it so we can get it as good as the vray bump in c4d? It is very good and really eliminates the need for normal mapping or displacement in many cases even if it is an old visual hack.

Has this also an influence on the rounded edge feature which has disappeared from / broken in the corona C4D version?

Cheers

[iacdxb]

Many rounds of beta but this bump not seeing any such pointed improvement. Bump mapping and rewrite corona core... I think take time and hope it will be fixed till next beta or final release.

Thanks.

...

[iacdxb]

Hi,

Any bump update in Beta  release, its fixed in core or still same as earlier....?


Thanks.

[Eddoron]

IIRC it's been partially fixed. Just try the latest release and see if things have gotten better for you.
Maybe crank up the "Max normal diff" in the dev/experimental stuff in the render settings.(dev mode has to be enabled)