You may convert the hairs to the polygons to render them, I have seen such tricks. However, the native hair & spline support will be added in 0.66 release. I am working on this, but before that need to finish the complex 0.65 update

Your override Skies with CentiLeo tags should be not first Sky in the scene. And you drag and drop them to the tag with overrides of the first Sky object. Yes you can override Reflection, Transmission, Camera, Diffuse, SSS overrides. You can also override the Sky that draws the shadows on the shadow catcher / matte object

Filip Stamate, welcome to the rising CentiLeo world! Thanks for images and suggestions!
I will reply in more detail later, as for now I can say CentiLeo supports multiple Sky objects to work with Camera (backround), reflections, diffuse and etc. As you correctly noticed the primary Sky object is the first one in the scene. It manages everything. And you need to attach CentiLeo environment tag to it. Inside this tag you can find Override Tab where there are several layers to override. You may just create several extra Sky objects (with centileo tags!) and assign different HDRI image there. And after that just drag and drop these extra Sky objects to the overrides of the first "manager" Sky. That will work. Later I will make many more supprted HDRIs that will be able to assign and override per material. There will be 10s or 20s of them supported.
I will fix Dirt shader of course, it basically will be do same as AO/Curvature. Don't know why Redshift has two nodes probably because of legacy reasons, but the process is similar in both nodes.
Will reply in more detail later. Improving the new tesselator for displacements now

Oh btw this Dirt node is currently just not working as expected. I have to fix it, it's like AO texture

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ssjenforcer wrote: I tried using the layer node, but for some reason only one of my surface imperfection textures works. Any other one I try doesn't work or show up as a layer.

This Layer node has on/off toggles for each other layer, probably you forget them. Also each layer mix mode is different. They are all standart, but need to test to understand how they work for specific case

I would advice to make a multi-material or mix material to make the smudges on top of glass car window.
For example the Mix Material:
1) Primary material would be a diffuse material with smudges and sand textures
2) Secondary material would be a glass of window with reflections and IOR and all the staff as for clean glass
3) Primary material amount - is the alpha map texture with white regions encoding places where smudges should appear on the window. Primary material is on top of Secondary.
These layers of mixed materials will just help to resolve the Alpha channel of individual materials easilly and no need to deal with roughness of transmission which is wrong in this case

Video tips are more time consuming to produce than text + images. So the documentation itselft will come first and next the videos, I will invite more people for that of course.
As for now, I am doing some complex technology improvements but the end for them is approaching fortunatelly

We have more than Octane in this department:
1) There is a Layer texture node. It accepts 7 input nodes that are stacked onto each other and you can integrate each input texture on top of each other with many layer options like in Photoshop. Just check it. It's a nice way to combine imperfections, noises, bitmaps with this.
2) As for Add/Multiply they are also there. CentiLeo has Math node which supports the basic math operations with input textures. It's just placed in a different category of nodes: not a Node Generator, but Math

Yes, CentiLeo renders internal reflections within the glass very efficiently. Less noise than other renderers. Keep in mind CentiLeo has Direct Light Clamp parameter in render settings, it's global, not per-material. This paramter has influence on the brightness of the highlights also for internal reflections.

Thank you for scene! Will check it and get back to you. Currently I don't have installed Blender, but will analyze the situation with the icecubes.
I would like to share some specific thing that can be relevant to this scene as well. Have a look at Maxwell Render documentation last figure:
https://nextlimitsupport.atlassian.net/wiki/spaces/maxwell/pages/22684680/Nested+dielectrics I hope they don't mind )
So looking at the last figure you may see that a good way of modeling the overlapping refractive objects like bottle glass and water object is to use the concept of nested dielectrics. According to this concept the water object borders (see red line on the figure) overlap the glass object. Both are refractive and have different IORs. To resolve this physically some renderers use the priorities but CentiLeo uses "Is Liquid" setting in Transmission Tab. Is Liquid should be set On for liquids like water in this case in case of overlap and it will help to make correct refractions.
The other nice thing is the ability to set IOR smaller than 1. In this case you can use not the overlap but model the bottle-water objects as one object with the borders between glass and water mediums. And on the interface (the surface) between both mediums the IOR of material should be relative IOR equal to IOR(glass) / IOR(water). This can take some computations, but it will result in another way of correct modelling. However the "Is Liquid" concept is simpler Sure I will describe all of this in a documentation with examples

May you drop a scene to me to info@centileo.com for experiments with icecubes? With HDR texture, maybe using dropbox or google drive or some other filesharer.
Probably we can start with Transmission and/or Absorption = white and then start changing to get where it become different.
Also there seems to be the difference with gamma on rendered image or HDR itself. Or with expsure that you multiply for CentiLeo to get less dark, but still there is a difference.

Actually I see some reftaction pattern similarities in CentiLeo and RPR. But the lighting direction and highlights are differernt! Even the blue paper cover around the bottle have different highlights for both engines. At first try to make the lighting exact everywhere. For example start with identical HDR or Area rectangle or Directional light sources for both engines.
Another thing is that you have the ice cubes and water droplets on the bottle. These objects overlap with other refractive surfaces: with the water around and with the bottle plastic object. I would recommend to set and test "Is Liquid" for water in the bottle and the water around.

thrimanakatha, in CentiLeo refraction works the same way as in any other renderer: same values, same behavior. Refraction is managed in Transmission tab of material. So you have to enable Transmission toggle in the list of material layers, by default this toggle is off and you may see it black because of this. IOR is working the same way as everywhere. For example to make the water, you can switch On Reflection1 and Transmission in the list of material layers, set IOR = 1.4 for both Reflection1 and Transmission layers, leave weight = 1 and colors white and make roughness = 0 for both reflection and refraction.
If the shape of your object is complex the refaction may produce some black regions on image and to fix it you need more ray bounces. By default there are 8 ray bounces, they can be changed in render settings.
Also one other reason why you don't see refraction may be very high value for Reflection1 IOR if you use it. Usually refraction and reflection are combined, just make some 1.4 or 1.5 or something like that IOR for both and test results

thrimanakatha, sure! All you tell about is what I am also thinking. Actually CentiLeo output node doesn't expose the viewport color to the node in that node area. This viewport color port is one of the ports in output node parameters, and you can connect from there. The idea was to add the ability to connect any texture to this slot (diffuse, reflection textures, roughness, many others) just for tests and modeling purposes. But it's better to start with diffuse texture by default for viewport color and change it for different if something is connected.
Sure more render passes are in short term passes, they are very much needed.
Also the current development version has large accelerations especially for scene geometry compilation that happens between modeling and rendering passes.

Yes I think to make default diffuse to avoid this confusion. However my original goal was to encourage all to use IPR output more than viewport for uvw and texture modifications

thrimanakatha, as I already said you can setup the viewport color or texture in CentiLeo Output node, there is a viewport color slot there

Check the settings of the viewport. Non-node CentiLeo materials show textures in the viewport, I see them right now. As for the node materials just make connections. Working with connections in node space is very simple, it's just like nesting your textures to do a lot of complex operations

Are you confused with Cinema node system or with CentiLeo node space in particular inside Cinema node system? CentiLeo nodes just copy the functionality of old-style menu materials and shaders. But the difference is with the node display with connections.
In old menu based materials the centileo materials should be outputed to the viewport with all textures by default as far as I remember. Maybe it's switched off by yourself in display settings of C4D viewport

Ha-ha! If you use node based materials then you need to connect any texture / node you like to the Viewport Color port of the Output material node. So this is organized this way just not to overload the viewport with textures and not to waste the memory resources. But if you need to see something you can make this connection.
Actually I haven't made this default texture output to the viewport only because we have it in IPR which shows the textures at full precision and in arbitrary resoultion and it's fast enough for working with UV editing.

CentiLeo has interactiv preview render mode (IPR) which allows to see what you edit for geometry, light sources, camera and materials. You don't need to render the animation upfront and then see results. With IPR you can see the ongoing work in real-time. Also CentiLeo material textures are displayed in the viewport as well, but in lower resolution.
The transparent could be not working because of IOR value, it refracts with IOR = 1.4 by default. However Alpha doesn't have IOR, it's the same as refraction with IOR = 1.
As for material converter then of course we need it so much