Concrete Wall [C&C Needed]

Tetranome · Jan 2015

Hey! So I'm fairly new to PBR, and I'm sort of struggling to get my materials to fully take advantage of it.

Here's an aged concrete block wall I made yesterday:

The end result is alright, but it isn't top tier work. Can anyone see any big mistakes I'm making? C&C much appreciated

Thanks Polycount!

Obscura · Jan 2015

Yes. Its the "specular map". You need a metalness map, but since its entirely non metal, you can plug a constant1 (0) to the metalness slot, and you should pull out your specular map. Its not needed at all. The specular parameter in unreal4 is for the specularity of the non metal surfaces. If I remember right, then the default spec value is 0,5 and you should not change it. Maybe the green channel of your normalmap is also inverted but I couldn't tell with this lighting.

In ue4, the metalness map determines the amount of reflectivity.

Tetranome · Jan 2015

Ahh I had no idea Specularity was irrelevant now. I've checked out the normal map, it seems fine - but I'll probably increase the strength to make the borders between bricks more intense.

On the note of specularity, does that mean I now put highlights in my roughness/gloss?

Thanks for your help

Obscura · Jan 2015

Basically yes but you should not add random "highlights". They should be added only with reason. I mean you should not add "edge highlighting" or anything like this. Just think on it, there are no "edge highlights" in the real life, its not more or less reflecvity or glossy at the edges, just if there are damages or anything that changes the nature of the surface.
One more thing, an ao map could also help. It can be handled separately , it can react to the lighting, so it worth to add.

Tetranome · Jan 2015

Ah alright. I had a few people tell me to add slight edge highlights for an artistic touch - I guess it depends on what you're going for... maybe it's a more stylized approach.

Thanks, I'll try out AO!

BagelHero · Jan 2015

For the record, you can use spec with pbr, just not in UE4 by default. Metalness simplifies everything, but it is still just assigning spec values. Will edit this post with links and better explanations in a little bit, @ phone right now.

EDIT: Alright. So, read these. Hopefully they'll clarify the whole "Metalness and Spec are both viable methods" thing. The important thing is, if you're working with UE4 out of the box, the option of using the Specular workflow is not open to you, so you have to stick with correct Metalness maps. In your case, here, you wouldn't even need one, it would just be black.
http://www.marmoset.co/toolbag/learn/pbr-theory
http://www.marmoset.co/toolbag/learn/pbr-practice
http://www.marmoset.co/toolbag/learn/pbr-conversion

As for roughness/gloss, yours appears to be a bit glossy right now. Afterall, when I think of concrete I think "rough". Also not really feeling that the result you're getting from your wall's high poly > Normal map is really accurate? What are you baking in? I also second that it seems like the green channel is inverted but you say you've already checked that.

Finally, take the AO/Cavity information out of your Albedo ("diffuse"), put the AO bake information in the AO slot separately so the engine can occlude it accurately.

Looking forward to seeing more, hope this can help a bit.

Tetranome · Jan 2015

Awesome, looking forward to the edit.

BagelHero · Jan 2015

Just a little bump to make sure you saw the edit.

Tetranome · Jan 2015

Hey! So I did some snooping around, turns out I've been baking normal maps incorrectly from xNormal since I started. I had no idea it inverted the green channel, so I've gone ahead and fixed that.

The reason that normal map looks so strange is because I ran it through nDo afterwards, and although I thought it improved it, it simply didn't.

Here's the raw bake with flipped green:

As for the glossiness issue, I'm going to read up on it now through the links you posted. I also found a few videos on YouTube that look helpful!

Thanks so much for the help man, I can't believe I've been baking my maps wrong out of xNormal for 2 years.

---

UPDATE:
Here's how it's looking now. I think i'll rework the gloss and diffuse.

BagelHero · Jan 2015

Ayyyy, way better!

JackDCaron · Jan 2015

You have the ability to invert the green channel in Unreal as well if you double click your texture to open the editor. It is not necessarily wrong to have the green channel either way, just depends on where it's going.

As for the Spec/Gloss discussion, it's best to think of them as two separate entities. Specular refers to the intensity of reflected light coming off the material and is often faked or cheated in many cases (and can make things look very CG because you're disregarding energy conservation). Gloss (or roughness depending on engine) refers to how smooth the surface of the object is, so painting in a highlight won't work, you'll actually just be painting in how shiny parts are. Make sense?

Cay · Jan 2015

If you wanna make this even more realistic you might wanna think about some variation in the color of the bricks.. make some slightly darker/brighter and so on.. but I of course don't know your reference.. and maybe those look very much all the same.. but it makes the whole thing a lot more interesting.. you could also leave some space for grout
It's a very nice start, though.. and the normal came out great!

Tetranome · Jan 2015

@JackDCaron
Thanks for that, makes sense! And that's great that you can invert it in the editor, helps me fix up the inverted channels from previous work!

@Cay
I usually find when I try color variation it simply looks bad, but that's because I tend to just slap a perlin noise with multiply and opacity over top. I need to start hand painting stuff in and using different hues I suppose! Another big mistake I made was not really using a set reference - and I know I should haha! Thanks for the tip

Concrete Wall [C&C Needed]

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