Alpha images in Cycles

[Mateusz]

Hi. I’m playing around with alpha images. When I’m using few images it looks lovely

However while bunching bigger object together it looks horrible mess in Cycles

Here is Eevee for compare

Any idea what could that be? Please

[FedPete]

Yes, this is unexpected!
My first clue for Cycles was, your material nodes construct isn’t good.
But I assume, you are using the same material node construct for Eevee?

Also strange, you are giving us screen dumps, but in which mode?
Because Even if your end render is Cycles, in some viewport modes Eevee is still used.

Show us your complete window, as in mainmenu > window > save screen shot.

Show us your material node setup.

[Mateusz]

Im using render preview mode. There isnt node setup. I have png with alpha chanell. Albedo goes in to the colour and alpha chanell goes to alpha socket on principled Bsdf shader and thats it…
Here are proper screen shots. Sorry I’ve made the same mistake like everybody else.
Cycles preview

Eevee preview

Node setup

Cycles render

[Grey_Mongrel]

Has been a long time since I touched blender and I am not sure how exactly these were constructed, but the first thing that popped into my head was it looks like the same result you can get from flipped normals.

Unlikely to be on the mark but it may give you something else to think about.

[Mateusz]

Just stacking alpha images next to each other

[Grey_Mongrel]

Fair enough, I thought you may have had each alpha image on a separate poly plane.

[Mateusz]

Hehe. Now I don’t know what you are talking about
I mean they are one image imported as plane. That duplicated and transformed. About it. Should I have used some node setup?

[Grey_Mongrel]

As I said I have been out of 3D for awhile, but my understanding is that every image you import is on its own polygon. That would mean they have a normal direction.

In your viewport click the overlays menu and choose face orientation, it should show you if they are the same or not based on the colour.

[Mateusz]

Ah. I know what you mean now. yes they all face correctly.

[NP5]

I seem to recall from the 2.7 course there is something or was, that you needed to increase when using lots of alpha images. On the lines that it only sees through a certain number unless you increase it. No idea if that is the problem, but a possibility?

Edit. Some research later.

Try render properties tab, Light paths dropdown, Max bounces dropdown, Transparency, increase the number.

[FedPete]

Yes, I think NP5 is on the right track.
I remember this now also, it was the rabbit grass part. Import grass bitmaps, and with too many planes, blender got confused … shadow option thingy to be solved by an option increase.

[Digitz]

This is 100% an issue with your light paths. Whichever version of Blender you are using, go to the Render Settings tab and set your Light Paths, Max Bounces, Transparency to something like 40.

[Mateusz]

Thank guys. Light Paths setting have done the trick. Much appreciated.
Only one person can be marked for solution. Bummer!

[sdoriginal18]

May we see that crispy final render?

[Mateusz]

You sure will that was just a mockup.
Still playing with whole wing construction.
Trying to source set of feathers for all different lyers. But i think ill make my own feathers using particle system, render alpha images and than use them.
Will take few days
God damned day work in the way!!!

[sdoriginal18]

eagerly awaiting that! Great work! Day work can be such a drag with a fun project waiting at home huh!

[Mateusz]

Like I said this are just a mockup. One image, nothing matched. Just an idea to see what it would look like.
But I felt compelled to show results of help I got so here are renders both Cycles and Eevee to compare.
Ive set bounces of transparency to 40 and that got read of nasty shadows but image was still yellowy. Ive plugged image in to emission strength socket passed trough colour ramp and math node set to multiply x2 and that got it nice and white
Cycles

Eevee

Unfortunately its all I have energy to do today 14h shift.
Good night
I still like Eevee better. But rest of things are nicer in cycles. Got to compromise.