emitter casting shadow even with cast shadow in off position?

JPayne

DS 4.9 Just as the title say's...emitter casting shadow even with cast shadow in off position? The flames are set as emitters and in the parameters tab cast shadows is in the off position. This shows in the attached image crop. There is a spotlight in the scene along with the flame emitters but shouldn't any object with cast shadows in the off position not cast a shadow?

Zilvergrafix

We need more info. I can assume is 3Delight instead iRay rendering?

Flames were emitters I'm not seeing color bledding around the upper surface of the cake due to the candle wax objects.

Emitters and spotlights acts differently, I'm seeing Raytraced shadows below the cake, I assume Spotlight  is not an emitter.

if it's iRay the cam uses it's own light too and you need to turn off.

 

JPayne

Nah, this is Iray. The cam light is off naturally as there is a spotlight in the scene. There was also a point light in the center of the cake as I wanted a wider area affected. I rerendered the scene with 3delight and the flame shapes did not cast a shadow as expected. When I turned cast shadows on they behaved in the way you would expect... They cast shadows.

Zilvergrafix

for a wider area being illuminated is bettter increase the lumens of your flamme emitters, if you want the entire scene being illuminated globally, choose an HDRI image instead for a replace for point and spotlights.

 

that's the way I would do in terms of evaluate what is creating such shadows.

Khory

Just like in the real world you can't turn shadows off on lights in Iray. 3DL on the other hand will let you fudge reality as far as lighting goes.  Perhaps instead of a point on the cake (which is going to add another shadow caster) try a Photometric light that has been changed to a shape like rectangular and made large (maybe 50 by 50). A light like that should cast a more diffused shadow that won't be as obvious.

JPayne

I turned off shadow cast on an object, not the light.

mjc1016

JPayne said:

I turned off shadow cast on an object, not the light.

Not a setting that Iray will respect...

You can't turn off the ability of an object to cast shadows in real life, so you can't do it in Iray Photoreal mode, either.  It's just not going to happen...

Now in the other mode or with other features, you can control what casts shadows.

Zilvergrafix

btw, the Cake is a freebie?, I would like to reproduce the issue on my own pace.

looks interesting because is an issue that I never was aware of. 

JPayne

Cake was not a freebie purchased from another site. 

Not a setting that Iray will respect... Then why is it there? 

 

Cake was purchased from another site.

You can't turn off the ability of an object to cast shadows in real life, so you can't do it in Iray Photoreal mode, either.  It's just not going to happen... I just find that absurd. A flame is not a solid the flame itself should not be seen as a shadow. If Iray really behaved as real life... there would be atmospherics for real life bloom and soft edges of lighting. It's still all faked. People aren't 1 polygon thick. It's through shaders that you can fake mass.

 

 

mjc1016

JPayne said:

Cake was not a freebie purchased from another site. 

Not a setting that Iray will respect... Then why is it there? 

Because it is a parameter not a surface setting...parameters are tied to the mesh, not the surface. So, it could be that removing/not displaying it may not be possible and still have it functional in 3Delight.

 

JPayne said:

I just find that absurd. A flame is not a solid the flame itself should not be seen as a shadow. If Iray really behaved as real life... there would be atmospherics for real life bloom and soft edges of lighting. It's still all faked. People aren't 1 polygon thick. It's through shaders that you can fake mass.
 

And yet, flames DO cast shadows...so does glass and other transparent items.

All it takes is a light source brighter than the flame shining onto the flame.

Zilvergrafix

After some series of conclusions...There is NO CAST SHADOWS in iray uber shader presets, probably you are using another type of shader that is only compatible with 3Delight

I did 2 renders, it's hard to tell if candlelights are visible because no raytraced shadows involved, and there is 10 different sources of light on different angles causing different angles of the body of the candles, in some cases the "shadow" of the light maybe is the another shadow from another candle light, but judge by yourselves.

Zilvergrafix

mjc1016 said:

 

And yet, flames DO cast shadows...so does glass and other transparent items.

All it takes is a light source brighter than the flame shining onto the flame.

 

yep.

mjc1016

Zilvergrafix said:

mjc1016 said:

 

And yet, flames DO cast shadows...so does glass and other transparent items.

All it takes is a light source brighter than the flame shining onto the flame.

 

yep.

And what it looks like to me is that the light source hitting the cake is definitely brighter than the candle flames (if they are actually emitting any light...unlike your candles, which are very obviously brighter).

JPayne

I can see shadows of the flames on the wall. Not from the flame but the actual flame

I had mentioned turning off shadows in the object parameter tab not the shader. The emitter flame should not be affected by a spotlight and actually cast a shadow, especially when turning off "cast shadows" in the parameter tab. Of course, a candle can cast a shadow but not of the flame itself.

 

Zilvergrafix said:

After some series of conclusions...There is NO CAST SHADOWS in iray uber shader presets, probably you are using another type of shader that is only compatible with 3Delight

I did 2 renders, it's hard to tell if candlelights are visible because no raytraced shadows involved, and there is 10 different sources of light on different angles causing different angles of the body of the candles, in some cases the "shadow" of the light maybe is the another shadow from another candle light, but judge by yourselves.

 

mjc1016 said:

Zilvergrafix said:

mjc1016 said:

 

And yet, flames DO cast shadows...so does glass and other transparent items.

All it takes is a light source brighter than the flame shining onto the flame.

 

yep.

And what it looks like to me is that the light source hitting the cake is definitely brighter than the candle flames (if they are actually emitting any light...unlike your candles, which are very obviously brighter).

Yes, as I have pointed out there is a spotlight coming from the left front of the cake. It's brighter than the candle light. There is also a pointlight in the center of the candle group. these are what is casting the shadow in the image. A flame itself will not cast a shadow of a flame volume. Zilver your last image shows this. The flame is casting light not a shadow of the flame. The wick will cast a shadow as will the candle but not the actual flame.

prixat

Have you tried a very low (but not zero) value in 'Cutout Opacity' on your flame object?

JPayne

prixat said:

Have you tried a very low (but not zero) value in 'Cutout Opacity' on your flame object?

I haven't actually, although I'm sure it would help some as a work-around

mjc1016

The way my kitchen is, the afternoon sun streams in the window and hits the stove.

So what?

It's a gas stove.  I get to look at flame shadows almost any sunny afternoon.

Flames cast shadows!

Plus, as far as Iray is concerned, it isn't a flame.  You haven't defined it as one and it is not emitting light. 

The 'cast shadow' parameter is a geometry parameter that only has meaning for 3Delight.

You want to get rid of the shadows...get rid of the point light, make the flames emissive...that would be much closer to 'real', that way.,

JPayne

mjc1016 said:

The way my kitchen is, the afternoon sun streams in the window and hits the stove.

So what?

It's a gas stove.  I get to look at flame shadows almost any sunny afternoon.

Flames cast shadows!

Plus, as far as Iray is concerned, it isn't a flame.  You haven't defined it as one and it is not emitting light. 

The 'cast shadow' parameter is a geometry parameter that only has meaning for 3Delight.

You want to get rid of the shadows...get rid of the point light, make the flames emissive...that would be much closer to 'real', that way.,

The flames are emitters as mentioned in the original post. 

Zilvergrafix

JPayne said:

I had mentioned turning off shadows in the object parameter tab not the shader. The emitter flame should not be affected by a spotlight and actually cast a shadow, especially when turning off "cast shadows" in the parameter tab. Of course, a candle can cast a shadow but not of the flame itself.

I can't see shadows this time but I have a beautiful freebie cake, I've learned something since yesterday and now I'm inspired to do a rendering with toons celebrating a birthday, cheers!

mjc1016

Run a render with just the candles.  It doesn't have to be fully resolved, just a few iterations should show if they are actually doing anything.  If they are set right there should be no need for a point light in the middle of the cake.  And then they should be bright enough to cancel/offset the shadowing caused by the spot.  As they are, right now, they aren't contributing much, if anything...what are they set at?

 

kitakoredaz

I have already found answer about not cast shadow but emit in iray.

Already mentioned above,, you acn use cut out opacity..

but I prefer choose transmission.  because,, actuall flame should transmission Lay I feel.

 

I use my originall emission shader. it can set transmission but I believe,, if you tweak reflaction weight,  (not reflection,,sorry)

to 1.00 then set IOR 1.00,   reflaction color (1.0 1.0 1.0 ) should transmit lay (no cast shadow) but,, emit.

 

see my pic.

1.  set candle with my shader.. no scene light,, we can not clear see shadow of candle.

2. add spot light, now I can see shadow of each flame (emitter mesh)

3  I set one canlde emitter, my shader, then set reflaction.  now only the candle frame not cast shadow

4.  to confirm it keep emission,, I  remove spot light, and remove another candle emission. (I set reflaction for two flames, = no visible)

JPayne

.

JPayne

kitakoredaz said:

I have already found answer about not cast shadow but emit in iray.

Already mentioned above,, you acn use cut out opacity..

but I prefer choose transmission.  because,, actuall flame should transmission Lay I feel.

 

I use my originall emission shader. it can set transmission but I believe,, if you tweak reflaction weight,  (not reflection,,sorry)

to 1.00 then set IOR 1.00,   reflaction color (1.0 1.0 1.0 ) should transmit lay (no cast shadow) but,, emit.

 

see my pic.

1.  set candle with my shader.. no scene light,, we can not clear see shadow of candle.

2. add spot light, now I can see shadow of each flame (emitter mesh)

3  I set one canlde emitter, my shader, then set reflaction.  now only the candle frame not cast shadow

4.  to confirm it keep emission,, I  remove spot light, and remove another candle emission. (I set reflaction for two flames, = no visible)

This did the trick kitakoredaz:) I am posting a small example of each lighting solution labeled A, B, and C. 

A Shows candle light and a mild HDRI background setting.

B Shows candle light with 2 spotlights for fill. Note the red circle as it shows the old emitter shader showing the flame shadow.

C Shows Identical image as B using a refraction Weight of 1 on the emitter. This is what I was expecting and has solved my issue.

Thanks to all the folks that tried to help figure this out especially to Kitakoredaz for actually finding the solution.

Tobor

You might make note of this thread, from back in October. It discusses some of the variations in hiding emissive geometries (while still casting light), and makes note of shadow-casting when using some of the methods. Note that in your use-case, you wouldn't want #3, because by design it casts a shadow from the matted object, even when you hide it using method #1.

http://www.daz3d.com/forums/discussion/comment/922409/#Comment_922409

As a BTW, if you're seeing a "shadow" option in a surface shader, you don't have the proper Iray materials applied to that object. It might be a 3DL shader, for instance. This can lead to unknown results, because the shader must be converted on-the-fly right before the render commences, and you never know how this conversion will be applied. It is always best to manually apply the Iray Uber base to all surfaces, then select the sub-surface type (like Emissive), and make manual adjustments as needed.

Note that Iray actually does support shadow casting features, but it requires switching it first to Interactive mode. From there, you can select various Shadow settings (these settings are intentionally made invisible in Photoreal mode, as they have no effect there, so don't try to cheat and unhide hidden parameters -- there's a reason they're hidden). However, light case from emissive objects will no longer show. This is a known limitation of Iray.