Cycles billboarding problem with alpha

Im having a problem with renders like this:



This is simple cycles setup applying color texture to diffuse shader of the plane with attached transparency shader mixed with help of alpha channel:


and here’s source object for rendering particles:

Thing is, when objects are not over each other, things look fine, but when it’s too dense, it starts doing wierd shadows like this. Even when material setup result is fully transparent.

Thanks for your help

You’re welcome.
I’m not a big fan of the search function in this forum, so I usually find it more helpful to just quickly link back to my own answers to similar questions…:wink:

Im not a big fan of posting “dumb question” like this, but some specific problems are hard to google. Link indeed is an answer so its fine with me. :slight_smile:

Hi there fellowship of the Blend!

I’m here with another tricky thing that bothers me…

Look at this render, everything goes fine…


Except when you take closeup view (upscaled by 400%)


I did same setup as with grass above (scroll up) using .png with alpha channel, did some research and ended with diffuse texture png with white background and B/W Mask.

But still there are those artifacts!

Those lines are around the edge of stem plane, thing is there are better visible when there’s more of them.
Alpha mask is PURE BLACK around the edges that it should be 100% transparent. I know it, i did it ten times again and again :slight_smile: I’d spent 4 hours on that matter yesterday…

Here’s what the tree looks like in 3D view:


And here’s my node setup. I also tryied to mute transluscent BSDF, but without any effect on artifacts.


Any help appriciated with promise of sending deep thanks and smiley back :slight_smile:

Have you tried running the texture coords through a mapping node with min/max enabled (clamping)?

As I promised, there’s smiley guy: :slight_smile:

Thank you very much. I enabled it but i have no clue what values should i put in. I’ll search blender manual… thanks anyway!

Raise the transparency bounces in the properties panel.

Usually the defaults do just fine. Clamping the the uv coords between 0 and 1.

Sometimes with uv mapped alpha textures like that (specifically your alpha mask), filtering can cause strange artifacts on the edges at glancing angles.

Also make sure the edges of the mask image are absolutely black, since errors on the mask can be a culprit too.

Hi. I thing this would help when increasing more than i did (I increased by two times from 4 to 8 bounces) this wont help “simplyfing” the scene and decresing render times… which was reson that i havent used procedural tree…

Thanks anyway

Ok. Something’s wrong with the texture maybe. Clamping had no use… This is pictures i stole from internet… so i’ll better go and make my own photography. Maybe using texture 512x512 would help.

Thanks anyway.

I just wanted to help with this because i had been thinking what if i wanted to use tree in detail. But as long as it is just part of background forest ill leave it.

Thank you all for your advices and if you got some idea, send me private message.