(Sun)light shining through a dress effect
IsaacNewton
Posts: 1,300
Could anyone suggest how I can achieve the effect of sun or other strong light shining through semi-transparent material in DS4.9. (see attached image for example)
I think Iray should be able to achieve this. I have tried putting a strong (up to 20 million lumens) spot light or a point light behind the dress with the dress at various transparencies, but I cannot get the glowing effect or the legs silhouetted by the bright light. The source of light needs to be hidden behind the figure else it shows as a sharp edged object (eg a disc), but as soon as it is hidden there is no glow.
I suppose I might cheat by making the dress fabric emmissive, but it might be difficult to get the gradual dispersion of light.
All suggestions will be welcome.
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Comments
This is, I think, a scatter and transmit thing - the light bounces through the fabric but the fabric isn't truly see-through (which is why the leg closer to the viewer in your iamge si clearer - there has been less dsitance for light bouncing from other directions to fill the shadow in).
You might also want to try cutout opacity; but it likely wont take much if you get the materials, and the light correct.
I assume scatter and transmit are material properties. How do I apply them? I don't see any reference to transmit or scatter in the surface parameters.
Is "cutout opacity" the same as Opacity? (There is an Opacity dial but no Cutout Opacity dial.
As you will appreciate from my questions, I'm a newbie at changing material/surface settings.
It sounds as if you are using a 3Delight shader, to set this up you will almost certainly need to select the surfaces of the dress and aply the Iray Uber Default shader
As Richard notes, change the surface using the Iray Uber shader, and then it'll be a proper format for Iray.
If you have any store-bought Iray shaders, you might find the ones for creating atmospheres or God rays to be useful starts.The dress has a volume, so you can treat it as a volumetric shape, and play with shaders designed for fog or smoke. These use subsurface scattering (plus other techniques) to give the material a sense of volume.
As a start, you might see what SSS shaders can do for you by playing with the red wax shader in the nVidia Examples folder, which is installed along side the Daz Iray Uber folder. These are a completely different set of shaders that don't use the generic Daz Uber material. The red wax shader is much simpler and easier to experiment with. You can change the color, but you can't add things like opacity maps or bump maps or other things that the Uber shader lets you do. But as I said, it's great for experimenting.
The values in the shader appear to be in centimeters, if I recall correctly.
Indeed I had forgotten that DAZ Studio applies 3Delight shaders by default. I'll have a play with the Iray materials.
I've been playing with Iray materials and it's hard to get it right...too much backlight and it's hard to see the main figure, too much from the front and effect is lost.
You can do it in a bunch of ways. I'd suggest a combination of translucence and cutout opacity.
That's what I was doing...getting the balance between back lighting and frontal light is the hard part. It's real easy to overpower it one way or the other...
Using a white plane as a bounce card to help light the front side helped a lot.
mjc1016, did you use the bounce card to bounce the strong back light on to the front of the figure instead of using a front light or as an extra to a front light? If the latter, then in what way is that different than using an extra front light?
I imagine that a bounce card can give a pretty diffuse light (at least in real life) but at the cost of considerable extra calculations (in virtual life).
Yes, instead of a front light...it was too easy to overpower it with a front light.
The 2 meter bounce card I used provided a nice diffuse light without overpowering anything and times weren't increased much, if any (didn't keep track but all my tests were running about 25-30 mins on my system).
Unfortunately I don't have any postable images...1) I didn't save most of them and 2) the ones I did save aren't going to pass TOS (didn't bother with full clothing or clay). If I get a chance I'll do a postable one with settings...trying to get yardwork/gardening done before it starts raining...again.
I know I'm late but just gonna add to this by saying I got a pretty good effect by enabling "thin walled" then adding some translucency to it, hope this helps
Thanks for the tip, Dumb an Furious.
Would it be possible for you to post an example of this effect?