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Hello there,

I was wondering how to make a simple white sunshade textile like sailcloth for exterior architectural viz.
It should render fast and there is no need for detail. It's not necessary to render the structure of the fabric.

But what I am aiming for is that the material should be bright, and a little bit translucent when light is shining through with front lighting.

Do I need SSS for it? I haven't seen anything like that in the mxm library.

Thanks for help,
Umdrehung

You might find this "tip of the day" post to be a helpful starting point:
http://www.maxwellrender.com/forum/view ... 73#p337773

Best,
Jason.

Thank you so much, Jason. That is exactly what I was looking for.
Umdrehung

Actually, that isnt a good start technically speaking, with thin-sss (like all transmissives) its not good to use additives, it causes fireflies with bright sun.

I can PM you something if needed, sounds like your happy already though.

umdrehung wrote:Thank you so much, Jason. That is exactly what I was looking for.
Umdrehung

I'm glad you like it, just one thing to be aware of -- make sure you use the material on a highly subdivided surface, because low-poly surfaces can show a moire effect... like this render using the drapery primitive: Best,
Jason.

Jason, that material doesnt work, use your eyes... do you see white sheets lit with sun.. no?

Your whole ghost-sss concept doesnt work, I know you mean well, but please stop pushing it on un-suspecting people who are looking for real help with a tricky problem. Quite frankly you dont know how to use maxwell much, just look at your renders, how deluded are you?



10 min render , no additives.

eric nixon wrote:Jason, that material doesnt work, use your eyes... do you see white sheets lit with sun.. no?

Your whole ghost-sss concept doesnt work, I know you mean well, but please stop pushing it on un-suspecting people who are looking for real help with a tricky problem. Quite frankly you dont know how to use maxwell much, just look at your renders, how deluded are you?



10 min render , no additives.

Maybe you are right Eric -- but I'm not sure you are the one who can say this definitively... your render doesn't back up your point very well. As for pushing anything on anybody -- it is entirely up to whomever is reading to make up thier own mind... I'm not sure how you think I am capable of of misleading anybody if I am so deluded? You said fireflies with sun -- but no fireflies appear... I'm not sure who is deluded here.

Really, I don't want to keep having these conversations with you... it just detracts from the forum for other users -- I think you would prefer for me to go away, but I have just as much right to post here as anybody.

Best,
Jason.

I think Jason approach is correct as one layer uses reflectance 0 and 90 with black transmittance and the other one uses transmittance (and thin sss) with black reflectance, so energy is not exceeded in any component.

I was using a similar solution too.

I may be wrong, though.

What does your mxm look like Eric?

Energy is exceeded, I have tested Jasons material, It gives fireflies.

My mxm is two thin-sss bsdf's in 1 layer, both ND3 (you can use higher nd's with thin sss - the light path is determined by the assymetry)
1 has neg assym -.5 for light which mostly passes through
Other layer has assym 0 for light which is mostly blocked, this carries most of the diffuse white as well.

To improve the spec I could add a normal map + anisotropy would represent the weave.

eric nixon wrote:Energy is exceeded, I have tested Jasons material, It gives fireflies.

I can confirm this. Firefly and smoothing artifacts abound:

looks like I used ND2 in the end;


The two layers represent two parts of the cloth from the point of view of a ray of light, the part which is thin, and the part which is thick - the centre of the fibres, which is more diffuse, in fact very bright.

Nice!

I would consider (the fireflyes problem) more a bug than a bad way of building material, wouldn't you?

I use that kind of materials quite a lot, but I mostly do exteriors so I don't have to go to very high SLs. I guess that's why fireflyes don't show very much here. I got some in interior shots with higher SL.

By the way, would the fireflyes appear if in Jasons material we set the thin sss layer at the bottom in normal mode and the opaque layer at top in additive? I think the look would be the same.

Additives are a really bad idea with anything transparent, because its impossible to stop energy building up as it gets focussed by repeating internal reflections.

As I undertand it thin-sss is not rendering correctly in terms of its appearance under emitters at the moment, so its best to test using HDRI,
and that issue is PART of the problem here too. Fernando you dont miss much

The bottom layer of a material is the same if you set it to normal or additive, because its only adding itself onto zero, so its the same thing either way.

@Half-wit, all those additive RAL materials are bogus as well, the brighter colours exceed energy and they all look wrong anyway. I think it would be good to remove them, do the newcomers a favour. I know you made them all by hand, and thats tragic, but also irrelevant.

Guys this gets too repetitive....share the knowledge and differing points of view but without the insults. We don't want to lock/delete threads which otherwise are useful.