Using gradients to make alpha - possible?

[atnreg]

This post is mainly meant for Juanjo but of course anyone is more than welcome to comment on this

I am trying to make candle flame and it works fine with LW renderer. It is based on luminous materials with gradient texture layers that adjust the transparency by object height (Y distance to object).

I have tried to make it to work in Octane but it seems not working no matter how I try to do it.
I know Octane cannot use LW texture layers but it can use LW procedurals so here's what I am trying:
Nodes: Octane diffuse mat,Octane texture image,DP kit Surface layer+
The surf layer+ contains the gradients as texture layers and its transparency output is connected to Octane texture image's Procedural input (also tried color output, no help) and the texture is connected to Octane diffuse material Opacity input.

It seems to do SOMETHING but not correctly so my main question is: is it possible to use the Procedural input like this? To me it looks like it could work as Octane generates the image map on the fly but it still may be impossible to do it like this in Octane.
Also is the Transmission comparable to LW's Luminosity or do I need to use Emitter node? If so, how I can make that gradient-built image map to act as emitter texture? I don't seem to get that to work either.

If that is impossible like that, then how can I do it? How can I adjust surface transparency with gradients based on object height? Using Octane gradients does not seem to work as they don't have the features that LW gradients have (like input parameter for object distance).

Am I totally on the way to destruction or is there still hope with this?

Any help will be highly appreciated

Antti

[BorisGoreta]

Well I'll try to answer since I don't have anything else to do.

Here is what I did, I think you are missing projection node plugged into texture image node and I am not sure Surface Layer+ works with Octane so I used Scalar Layer, you should copy your layers there by hand.

[BorisGoreta]

I think you can't translate procedurals directly this way becuase LW procedurals used in the Octane this way are applied to an empty image ( Octane image node ), then this image is applied to the Diffuse material using Projection node. I hope this is how it works.

[juanjgon]

I don't think that you can use kind of nodes with gradients in Octane. The procedural input is designed only for texture procedurals.

You should think in use an UV map or a Octane projection to apply your textures to the object, but you need texture maps. The gradients referenced to the objects are not available in Octane yet, and the LW ones don't work at all with Octane using the procedural input.

-Juanjo

[atnreg]

First, thank you very much all for your time on this

It's very sad that one of the most powerful features, the gradients, can't be used with the best ever render engine. I hope this will change soon, there are many things that can't be done without gradients and they are used in LW a lot. Even some kind of emulation or similar to Procedural on the fly creating of bitmap would be great.

But so currently there is no way to make a realistic candle flame except by faking it i.e. with photo of a real one, that's too bad.

Anyway, now I will not waste my time anymore with that so thank you again

Antti

[FrankPooleFloating]

Have you tried animating a displacement on candle flames? This might blow your friggin' mind.

[BorisGoreta]

I don't know what you're trying to do but for candle flames I model a simple flame shaped object, put it on top of a candle, make it diffuse and plug in emission node, set to black body, temperature around 2500 and it looks awesome for arch viz renderings at least. Add a little post processing node to get light streaks too. Forget LW texturing, you don't need it, I come from LW too and believe me, Octane texturing is far simpler then LW and produces much better results. So don't give up, if you need help please be more specific about what you're trying to achieve. I don't use gradients at all. Gradients are used to fake stuff or to help image look better. You don't need that in Octane because in Octane everything looks great from the start. You do have dedicated gradient node for Octane but I don't use it for texturing but for instance texturing variations. In LW I used gradients a lot to define reflection based on incidence angle. In Octane that is native to glossy and specular materials so you don't that here either.

[atnreg]

Have you tried animating a displacement on candle flames? This might blow your friggin' mind.

No I haven't and I have no idea how displacement would make flame look good so can you please explain more?
I am not doing animation, only still but I need as realistic candle flame as possible - preferably without photos of real flame (see image below in my next post)

Thank you for the idea!

Antti

[atnreg]

I don't know what you're trying to do but for candle flames I model a simple flame shaped object, put it on top of a candle, make it diffuse and plug in emission node, set to black body, temperature around 2500 and it looks awesome for arch viz renderings at least. Add a little post processing node to get light streaks too. Forget LW texturing, you don't need it, I come from LW too and believe me, Octane texturing is far simpler then LW and produces much better results. So don't give up, if you need help please be more specific about what you're trying to achieve. I don't use gradients at all. Gradients are used to fake stuff or to help image look better. You don't need that in Octane because in Octane everything looks great from the start. You do have dedicated gradient node for Octane but I don't use it for texturing but for instance texturing variations. In LW I used gradients a lot to define reflection based on incidence angle. In Octane that is native to glossy and specular materials so you don't that here either.

My goal is something like this (this is LW gradients in LW VPR, no photos)

I will try your tips but if you can give some more details, it would help me a lot, I am probably still thinking too 'LW-style' even though I know Octane does many things easier as it does not need to fake or make effects, it just uses the laws of nature

It will be about 20 hours until I'm here next time but I appreciate any ideas and help on this very much!

Thank you again

Antti

[FrankPooleFloating]

Oh atnreg, if you are talking stills (and this is a one-off and you might not do candles again anytime soon) you are doing yourself a disservice (imho) by not just comping flames. There is absolutely no need to try and create 3d flames when you can do a google image search of "candle flame" and just copy/paste one (or multiple) into PS and use whatever blend mode works best. So it is just a matter of making little yellow/orange emitters (where flames go) that are invisible to camera and plopping little flames into comp. You can't get better (more efficient - and real) than that. Personally, my clients would never pay for me to spend time reproducing perfect 3D flames for stills. Animation is another story, and I would encourage you or anyone to make a tear-shaped uv-mapped-orange-to-yellow model (as emitter) and hit it with animated displacement.

Edit: or like Boris says.