Specular and Roughness not PBR?

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  • Clemens Musterle


    See screenshot in attachment. A material with reflection and roughness set to 0 still shows reflections. So it seems that bug still exists when you use the opaque material shader in Revit 2019.


    I tried to attach the .rvt in the post but the forum will not allow it. Could you guys enable file extensions like .rvt , .rfa . skp , ... ?

  • Pieter There is no such material in nature/on earth with attributes 0 Roughness and 0 Reflection. That won't happen in reality.

    Such attributes should result in a definition error as they cannot be zero at the same time as they


    If you want to avoid reflections please set reflectance to 0 and roughness to 100.

    In the black wood scenario you would need to use

    • Texture map (including black spaces)
    • Bump map (for shadowing black spaces between laths)
    • Reflection map (100 Roughness for black spaces between laths)

    Quick example with different light angle and smaller spaces between the laths.


  • Pieter There is no such material in nature/on earth with attributes 0 Roughness and 0 Reflection. That won't happen in reality.

    Such attributes should result in a definition error as they cannot be zero at the same time as they


    How should be make a material like this then?


    https://cdn.cnn.com/cnn/.e/int…017/11/09/rotatingVB.webm


    I just want to make a material that has no (noticeable) reflections and that retains it color. With high values of roughness our colors are fading.

  • Vantablack has roughness of 100+ due nano technology. It is actually so rough that it is reflecting close to 0 light in any direction.

    But when the appearance is slighty changing when the light angle is changing.

    Please have a look

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    So basically it should be:

    • Roughness 100
    • Specular 0
    • Reflectance 0
    • Color Black

    This isn't resulting in real vantablack, but it should. I'll forward it to our developers.

  • Jonathan


    Perhaps the real problem I'm running into is that with roughness set to 0 our colors seem to fade.


    That's why we went to 0% roughness in the first place: to keep our colors (deep black) from fading.


    If we could keep more colors at 100% roughness there would be no need for us to try and go 0% specular and 0% roughness.


    I hope that makes sense?

  • Pieter Roughness indeed gives some shade of grey to the color. We'll check the feasibility.

  • Jonathan Knoefel


    Where you able to reproduce the issue or would it help if we provide additional examples? We are recreating this project in Enscape. It has a lot of strong black/white contrasts and we are running into a problem where the black's turn into medium greys. If we decrease the roughness we get the deep darks back, but the problem is that the problems are supposed to be mat (non-shiny).

  • Pieter I'm able to reproduce the behavior as mentioned above. But i don't see it as feature request and not as issue.

    I've forwarded it to our developers.

  • I can agree with the ventablack being a feature request (as its highly specific), but the fact that all materials with high roughness get a clearly visible gray tint shouldn't be considered a 'feature request', no?


    Very disappointed again on this topic, especially as it's been going on for months and every time you guys seem convinced, and then we're back to square one.


    I hope I will find some time soon to create a minimal example project to show how bad this issue is messing up our walkthroughs.

  • See attachments.


    The wall and ceiling are using the 'paint material' which is using a darker black compared to the 'metal material' that is on the elevator doors.


    Rendered in draft the wall is still clearly black (although the ceiling is starting to look more as grey). The wall is still 'darker' then the doors.

    Rendered in ultra the wall looks medium grey. The doors are now looking darker then the wall.


    It seems like metals are keeping their colors with high roughness but non-metals are being mixed with grey?

  • Very disappointed again on this topic, especially as it's been going on for months and every time you guys seem convinced, and then we're back to square one.


    I hope I will find some time soon to create a minimal example project to show how bad this issue is messing up our walkthroughs.


    If you're switching the topic into vanta black, we're back to square one in a slightly different topic. ;)


    All colors seems to be washed out due roughness, especially with light coming in from different angles. Colors get more intense when polished.

    =>That's why you see the difference between Draft mode, no light calculation, and Ultra, multiple ray bounces.


    Metals only look "Metal" due the reflection settings. Low Roughness and high Metallic/Glossiness values, which results in the slight color difference as mentioned above.

    Can you share the project with me for a further analysis?


    PS: I think the solution will be the introduction of vanta black material as option that could be added to all wanted material. Which means->Just the plain full intense color without any diffusion of light.

  • Hey Jonathan,


    First of, I really appreciate your continued engagement in this conversation :) !


    The only reason why we brought up the vanta black material was to illustrate a point. We picked an extreme example to illustrate a problem we often have with Enscape: we find it hard to create matte objects as they would appear in reality. On my desk I have a bunch of items that have no visible reflections and are strongly colored (deep black rubber, ...). When we create these objects in Enscape they often end up greyish. The trim of my monitor is a matte black plastic. There are never any reflections on it, so when I create this in Enscape I have to increase the roughness or otherwise it looks shiny. But when I do that, it no longer looks deep black but greyish.


    Is there any chance Enscape is just 'over-greying' objects with high roughness values?


    I'd be happy to share the project but it's a Revit one and I don't think there's an automatic way yet to gather all the image maps, so it might take a while before I can get to that.

  • I do not want to sound overly harsh, but is this the correct way to look at this issue from a computer graphics standpoint?


    No surfaces in nature/on earth are perfectly planar either, yet here we are trying to calculate a "realistic" fresnel on that surface. Pretty sure the qualities of the fresnel falloff curve would change with the microstructure of the material as well, rather than the linear gradient that seems to be in place as of today in Enscape.


    The whole point of computer graphics is to fake it until you make it. What good are a few realistic variables when the formula as a whole is not yet complete?

    There is no such material in nature/on earth with attributes 0 Roughness and 0 Reflection. That won't happen in reality.

    • Official Post

    Pretty sure the qualities of the fresnel falloff curve would change with the microstructure of the material as well, rather than the linear gradient that seems to be in place as of today in Enscape.

    Yes you're correct the microstructure (or microfacets) of the material has an effect on that - you can control exactly that using the roughness/glossiness settings in the material. A roughness of 0 however is a perfectly polished surface and as Jonathan said, for a polished surface you'll always going to have reflections on glancing angles due to fresnel.

  • This is a tricky topic. We take your requests seriously, but in this case we are dealing with a difference between expectations (intuition) and observation of material behavior. There is little space for arbitrary "gradients and falloffs" when implementing modern rendering models, which we follow closely. Those models (microfacet brdfs, energy conservation) are well advanced ("formula not complete") and we think we implemented them correctly. It may still happen that for dark albedos, low roughness and bright sourroundings your surface appears grey. If there would be a dirty hack we could remove it but there is not. If you want to check your material setup, check online PBR material resources with the roughness-specular parameterization. Roughness/F0 is equivalent but in other units.

  • we find it hard to create matte objects as they would appear in reality. On my desk I have a bunch of items that have no visible reflections and are strongly colored (deep black rubber, ...). When we create these objects in Enscape they often end up greyish. The trim of my monitor is a matte black plastic. There are never any reflections on it, so when I create this in Enscape I have to increase the roughness or otherwise it looks shiny. But when I do that, it no longer looks deep black but greyish.

    IRL the perceived 'depth' of the black (and the perceived colour of objects) is determined by the surrounding/bordering environment as much as the actual wavelengths of light that are bounced off the object to hit your eyes: If you modeled your office space with the correct lighting and set your monitor in it,then it would look matte black. If you take it out of context and put it in a white box, open to the sky, sitting on a white surface then it will look grey.


    If you want objects to appear like they would in reality, then you have to create a 'virtual reality' for them to sit within: The traditional way to achieve this result is to tweak the lighting/material effects in order to create a false reality/environment without actually having to model it. (Or make up for the lack of model/environment)


    Enscape has been designed to present environments with objects in them, not present objects with environments around them. {This is not a negative criticism or positive endorsement - just a fact. Personally I would prefer Enscape to concentrate on improving/developing the over-arcing environmental developments rather than smaller object based things.}

  • Again, the monitor is just an example. The real problem is that large surfaces that are painted Matt black in my interior are looking Grey. Entire environment is modeled.


    It's probably like Thomas mentioned: `It may still happen that for dark albedos, low roughness and bright sourroundings your surface appears grey`


    We did notice that you can kind off fake it by changing the material to a metal with very high roughness, although it also looks a bit off as well (although at least the color remains black instead of Grey).

    • Official Post

    I strongly discourage to use this workaround. All lighting calculations for transparent materials are a lot less accurate and having lot's of transparencies will lead to worse performance. So while you might succeed in getting a certain look in one scenario it might look a lot worse in others.

  • Are we at the point, where the final client need a black wall and the programmer says - no. ;)


    For me this is a classic problem of Enscape where the user needs to be adapted to the software, since the software usage range is to narrow or an automatism can't be avoided. But the problem will be the final client. The client is the reason why an artistic freedome is needed to go behind this limits. From time to time I miss the willingness to adapt the software to the user. I miss a solution for the image at post #30 and I'm curious - will the client get a dark wall? ;)