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Transparent emitter

Posted: Tue Sep 19, 2017 10:34 am
by GSTUDIOS
I am having trouble with a slight opacity in a supposedly transparent emitter. I created a dome light with an emissive colour on the front face and a simple transparent colour on the back face. I have tried various levels of brightness for the emitter and the transparent colour, but I am still getting a slight unwanted opacity to this emitter component. (dome light is in the centre of the flames in the fireplace - a slight shadow can be seen over part of the flame on the left)
FIREPLACE_wide_block_single_P_scene_5_sample_52.jpg
FIREPLACE_wide_block_single_P_scene_5_sample_52.jpg (1.25 MiB) Viewed 10499 times

Re: Transparent emitter

Posted: Tue Sep 19, 2017 12:24 pm
by Support
to be honest, I'm not seeing it. Can you draw a circle around it? How many samples the render did? have you made both side of the emitter 100% transparent?

Re: Transparent emitter

Posted: Tue Sep 19, 2017 12:43 pm
by GSTUDIOS
This light blue area indicates the location of the dome light (it has been squished quite thin). You will need to zoom in on the previous image to see a subtle dark area in the same region.
FIREPLACE_wide_block_single_P_scene_5_sample_52b.jpg
FIREPLACE_wide_block_single_P_scene_5_sample_52b.jpg (1.26 MiB) Viewed 10496 times

Re: Transparent emitter

Posted: Tue Sep 19, 2017 12:46 pm
by GSTUDIOS
It will only be a real problem when I render front views. These renders are only 52 samples.

Re: Transparent emitter

Posted: Tue Sep 19, 2017 12:53 pm
by Support
I'm still not seeing it but are you sure it's from the light and not an optical one? The glass does reflect the room. Does the shadow remain no matter the render angle? what if you zoom in and render it up close?

Re: Transparent emitter

Posted: Tue Sep 19, 2017 12:56 pm
by GSTUDIOS
The shadow remains regardless of the render angle and with the glass in front of the fire removed.

I will try a closer render.

Re: Transparent emitter

Posted: Tue Sep 19, 2017 1:03 pm
by Support
oh ok, yes, a closer render so I can see what you mean and maybe also one in performance mode with the light with 0% transparency so I can see where it is.

Re: Transparent emitter

Posted: Tue Sep 19, 2017 2:37 pm
by GSTUDIOS
This is a capture direct from the skp showing the exact position of the dome light.
FIREPLACE_wide_block_single_P_scene_7_visible.png
FIREPLACE_wide_block_single_P_scene_7_visible.png (459.34 KiB) Viewed 10492 times

Re: Transparent emitter

Posted: Tue Sep 19, 2017 2:39 pm
by GSTUDIOS
When rendering, the dome light is 100% transparent on the front and back faces.

The flame textures are about 80% transparent on curved surfaces which intersect with the dome light.

Re: Transparent emitter

Posted: Tue Sep 19, 2017 2:52 pm
by Support
oh I see, then you need to make the emitter double sided, make the back faces an emitter as well because the flames on the inside of the dome are not getting illuminated like the one on the outside.

Re: Transparent emitter

Posted: Tue Sep 19, 2017 2:58 pm
by GSTUDIOS
The dome light is an actual dome (top half of a sphere) which has been flattened a lot from front to back. The entire surface of the dome - front, back and bottom are all the same emissive colour, fully transparent. The interior of the dome is fully transparent but not emissive - I think making the interior emissive caused problems too.

As you mentioned, part of the flame images are inside the dome light where there is no emissive colour, but the flames are emissive themselves.

Re: Transparent emitter

Posted: Tue Sep 19, 2017 3:45 pm
by Support
That is the problem. in real life, you don't have a light bulb in flames where flames can get inside the light bulb. Why can't you use only the flames as an emitter?

Re: Transparent emitter

Posted: Tue Sep 19, 2017 6:14 pm
by GSTUDIOS
So far I have used a standard method of applying the flame textures to a curved surface, which gives the flames some three dimensional lighting effects during rendering, but not enough to light the hearth area sufficiently.

I can try other configurations where the dome light and flames don't intersect but that is not the technical issue I am still trying to resolve.

The dome light has a slight darkening effect to all areas behind it, and also casts a faint shadow.

A close up front view will help to demonstrate this - I will upload an example soon.

Re: Transparent emitter

Posted: Tue Sep 19, 2017 6:39 pm
by Support
I would use a solid rectangle instead and set the emitter Beam to none. I've played around with flames before and all I did was make it an emitter and raise the power and set the beam kind to none, but I'm not a designer so it may not looked right.

Re: Transparent emitter

Posted: Tue Sep 19, 2017 6:51 pm
by Support
Here, I just downloaded a fireplace from the 3D Warehouse and set the flames to 0% transparency, keeping the PNG transparency only, set the emitter to front and back and the beam kind to none, render for 60 sec and this is what I get...
Relaxed+L+Premium+(A-B).png
Relaxed+L+Premium+(A-B).png (548.8 KiB) Viewed 10486 times

Re: Transparent emitter

Posted: Wed Sep 20, 2017 11:49 am
by GSTUDIOS
Thanks - I just tried the beam none - I am looking for a very artistic effect and this setting doesn't cast enough light for me (I don't want the flames alone to emit too much light as they begin to look like very over exposed photos which is not the quality artistic effect I'm looking for).

Could I place 2 flame components (exact same size) in the same place and use different light settings for each? - (could be an upgrade for Raylectron v.5 - have multiple light settings for one emitter).

Alternatively, I might try to hide a very small dome light in a slot below the flames.

If you can examine the image I sent on high zoom and see the dome light "shadow", you may be able to determine if I made any settings errors.

It may seem like settings overkill, but bear in mind this fireplace model will be going on sale and used in dozens (if not hundreds) of future saleable models.

Re: Transparent emitter

Posted: Wed Sep 20, 2017 3:49 pm
by Support
I totally understand. What if you make a dome that cover all the flames instead? Oval shape that is and make the dome an emitter not the flames?

Re: Transparent emitter

Posted: Thu Sep 21, 2017 6:10 pm
by GSTUDIOS
I need the flames as emitters for realism of the flame effect and also for the way they reflect off other surfaces.

I will experiment with other dome light shapes to make them more similar in shape to the flames.

Re: Transparent emitter

Posted: Fri Sep 22, 2017 10:54 am
by GSTUDIOS
Here is the front view with a much clearer view of the dome light shadow.
Settings - emissive colour on the outside of the dome - 100% transparent. Interior colour 100% transparent as well.
FIREPLACE_wide_block_single_P_scene_1_sample_105.png
FIREPLACE_wide_block_single_P_scene_1_sample_105.png (6.36 MiB) Viewed 10451 times

Re: Transparent emitter

Posted: Fri Sep 22, 2017 3:00 pm
by Support
Have you set the back color to pure white?
is the dome power the same as the flame power?
the dome emitter, is it darker color than the flames?

Re: Transparent emitter

Posted: Sat Sep 23, 2017 1:54 am
by GSTUDIOS
I tried a few settings including pure white for the back colour - no setting seems to currently get rid of the issue, although I am sure I did some fireplace renders a few weeks back without the shadow.
The dome power is greater than the flame power. The flame power is limited to a natural flame look, just slightly overexposed.
The dome emitter is also a darker colour that the flames - the shadow lessens when the colour strength is reduced.

I already have a much better solution than trying to adjust settings. I have created 2 very small dome lights completely hidden behind the flames (looks more natural / accurate) - so far I have not seen any shadows or other anomalies.

I will upload a sample soon.

Re: Transparent emitter

Posted: Sat Sep 23, 2017 4:07 am
by Support
oh ok, is it possible if you can PM me a test skp file that I can use to test the dome one that produces shadow so I can find out what causes it? Not your model but just a box with the flames and dome.

Re: Transparent emitter

Posted: Tue Sep 26, 2017 12:53 pm
by GSTUDIOS
Here is a render using 2 very small dome lights hidden behind the flames - the hard bottom edge of each dome light may be casting shadows.

I will PM you with the problem dome light model shortly.
FIREPLACE_wide_refractive_accent_single_C_scene_1_sample_133b_watermarked.png
FIREPLACE_wide_refractive_accent_single_C_scene_1_sample_133b_watermarked.png (10.25 MiB) Viewed 10424 times

Re: Transparent emitter

Posted: Tue Sep 26, 2017 12:54 pm
by GSTUDIOS
with the last image upload - the dome lights were deliberately over exposed for effect.

Re: Transparent emitter

Posted: Tue Sep 26, 2017 9:06 pm
by Support
ok I found the problem. The flames object should not touch anything not be sitting below the bottom of the fireplace. The dome light back face color is set to gray and to have true 100% transparency, the color should be pure white, even if the transparency is set to 100%, to color will still be used.

I've replaced the dome light for a single triangle and made it an emitter on both side and used "beam kind = none" and it rendered nicer but...

the last problem was Raylectron, it does use the color just like any other materials even if the transparency is 100% so I changed it and I'll PM you the change...