4r7 horrible surface in viewport (can't read form correctly) help plz.

[Janvier]

Hi all, I recently got zbrush, and due to some problems I had to deal with, couldn’t get into like I wanted, until recently.

I purchased it when it was 4r6 (i think it was 4r6 p2) and ‘played’ a bit with it but that’s all, and I loved it. But then I upgraded to 4r7, and again, played just a bit with it, and still loved it, but as I said, couldn’t get really into it until recently, and now it’s patched at 4r7 p3.

So I’m really starting to put the hours into, learning and trying different stuff that suit my style, and suddenly, something big bother me, it bother me to a point where I can’t enjoy sculpting in that app anymore (yes it’s that big)

So I need your help figuring this out, because I don’t know if it’s my eyes that pick this up only now, or if it is the way zbrush deal with quad surface and ‘smooth normals’

Ok now that the introduction is made, let me show you exactly what is bothering me with some screenshots.

As you can see, this can’t be right, the effect is less eye damaging when resolution go up of course, but playing with the low resolution model is too important, and with such a bad surface reading…

and now the same model in sculptris, just as a quick comparison (I know they both are handling shading differently)

As you can see, although it can be argued that surface is less sharp in sculptris (and it’s true) at least the reading on the surface is correct, you don’t expect concave in the middle of a quad that is part of a convex surface for the most part.

What can possibly allow me to have a viewport that display the surface a bit closer than what sculptris does in zbrush? have something gone wrong in my update, is there a setting that I have messed up with that could explain this? Or is this how zbrush handle surfaces?

Again, i’m not certain if it’s the way zbrush handle surface (quads in particular) but my eyes picked this, and I can’t see anything else lately, I see it on every model, even spheres…

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[Synn]

Subdivide the mesh.

[Janvier]

Dynamic subdiv you mean? Yes I tried, it is better with quick grid based dynamic subdiv, bevel and chamfer off of course, but the problem is, it still give that impression of concave quad (less but still) and also the performance hit is a bit high, and the whole idea of working in low polygon is to have quick response in particular when you move large portion of the model.

If you meant subdividing, other than dynamic one, there is no point, the model is already subdivided to level 6, but I want to work in low subdivision to have more response and work the overal shapes, and I can’t do that well if the surfaces are not reading correctly, it’s hard to evaluate.

But yes dynamic subdiv is a touch better, at the cost of some performance, so that’s not really interesting me, even if it’s an option.

It really looks like a problem in the way zbrush deal in shading quads normals, if I triangulate the model, it’s a bit too sharp of course, but I have no more false surface reading (but I’m not interested in working with triangulated models, zbrush isn’t great sculpting with them, I’d rather go sculptris for triangulated)

Can someone tell me, if this is the normal way zbrush is dealing with shading on quads? Because I still have a hard time to believe this is normal, I’m certain something went wrong in my zbrush, maybe a setting or something, I can’t believe I wouldn’t have noticed this sooner if this was the normal way zbrush was shading the model in real time on the viewport.

here is with dynamic subdiv (which is too much of a performance hit unfortunately to be considered a solution) just for the comparison

better, but not quite, if you look carefuly, you’ll see the problem is just there, but instead of one fat big quad with the problem, there is tons of mini ugly quads inside all of them with that concave problem, but overall look smooth on the big quad.

[grogmcgee]

zbursh does not render surface normals in the same way as other 3d packages. zbrush renders everything as faceted. always. There’s nothing wrong with it it’s just how zbrush renders.

[Janvier]

@grogmcgee

You mean the first two image I posted, for you it look like normal low poly viewport shading in zbrush? Those horrible horizontal lines (with some attempt at gradient shading between them inside the quad) are the normal (and horrible) way zbrush deal with surface?

I’m sorry, but I hope you’re not right on that one, I just hope it’s just my zbrush that has problems.

Can you please take a screenshot of your zbrush of a low poly convex surface with those strange concave quad? put some low poly sphere or a model of your own. I could upload the model I took screenshot of if needed, but to demonstrate this I think you could use about any low poly concave surface. I just have a hard time believing it.

[grogmcgee]

yeah that’s normal - it’s just how zbrush shades things… it’s not really an low poly viewer…

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[marcus_civis]

If you want to edit a low poly mesh while viewing a high poly model then use Dynamic Subdivision. But you should not use Dynamic with ordinary subdivision, otherwise you will get a performance slowdown.

[Janvier]

@grogmcgee

Thx, indeed, then it’s crazy that I just get bothered by this now, I guess I will have to adapt my eyes to read surface this way, I still can’t believe I just recently noticed this.
I hope they will do something to get better low poly shading though, this can’t be right.

Well if there is anyway to reduce this concave quad effect withouth activating dynamic subdiv (because of performance hit) let me know.

[MentalFrog]

It’s not a problem with Zbrush it’s a design choice. Most 3D software by default will apply a smooth algorithm to your model, usually something like Gouraud shading.

Zbrush doesn’t do that. Instead it shows the flat shading of the actual polygon faces. Flat shading can be viewed in regular 3d programs like Blender, Maya, Max, etc. I don’t believe Sculptris has a flat shading option. Because Zbrush allows such high polycount subdivisions I find flat shading more useful. When I first started using Maya I got used to the smooth shading and found it useful as it showed me what the model should look like rendered. When I started into Zbrush I got used to the flat shading. I believe there is a way to view smooth shading in Zbrush but I don’t remember where it is. Instead I just move up and down subdivision levels as needed.

Now about your concave quad faces. Those are caused by non-planar faces.

Earlier 3d modelling software would not allow non-planar faces. Today’s modeller’s allow non-planar faces which can cause issues with lighting and triangulation. The faces that look concave are because the lighting is trying to light a non-planar face so half the face is in shadow while the other half is in light. Non-planar faces are very easy to get while using sculpting software such as Zbrush. Non-planar faces aren’t bad unless they’re extreme, such as your case. You don’t notice them in Sculptris because the shading is hiding them. This is where it’s useful to view flat shaded instead of smooth. If your model’s outline doesn’t look correct flat shaded then it needs better topology flow and/or more detail. Smooth and Flat shaded are both useful. You just need to learn when to use one over the other.

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[Janvier]

@MentalFrog

Yeah I know, that’s why triangulated don’t pose problem (even though it’s not really a solution in zbrush) but then i’d like to see a true flat shading (like flatten normals type) instead of this crazy attempt at shading that give concave surface depending of the angles. If there is a way to achieve that through some matcap or material maybe, or some setting that dial down the shading happening between the two triangles that would be good.

[Spyndel]

As someone explained above, if this really bothers you turn on dynamic subdivision when working at the lowest subdivision levels. On a moderate system, the performance hit isn’t any worse than working with the real time poly smoothing effect switched on in other programs. The key is to find the sweet spot for performance vs appearance with the “smooth subdivision level” slider in the dynamic subdivision menu slider. Working on a very low poly object you’ll likely want to turn it up for smoother appearance. If you increase the base subdivision level, you’ll want to decrease it to maintain performance. I have a custom interface with that slider on the edge of the screen for quick adjustments on the fly.

Or you could get used to it. I personally actually dislike the smoothing effect you speak of after years of working this way. I don’t like the performance impact (minimal as it is), and I dont feel it gives me accurate feedback on the surface I’m working on (if my polys are getting stretched and distorted due to suboptimal topology as they are in your pic, I want to be able to see that). In the traditional Zbrush workflow people work on objects at multiple subdivision levels, and quickly end up working with so many polygons this becomes a moot point. Perhaps if you give it some time.

Or, if there’s a tool you think is better suited to your preferences for sculpting, you could employ that tool instead.

Lots of options.