Is it possible to make a ceiling invisible at render, but still bounces light?
James
Posts: 1,029
Is it possible to make a ceiling invisible at render, but still bounces light?
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It's possible that Riversoft Art's Camera cutaway script may work. I beleive if you select (turn on) the clip lights option it will render as you wish, though I've never tried it.
You could head to the Daz PA Commercial Forums, Riversoft Arts always repsonds to questions on his products.
Or pehaps someone who has it can try it out.
I have it, but not at my Daz PC atm.
You can use an Iray section plane to do that. There is no need for Riversoft's script, but the script makes it easier.
it is quite simple to use the section planes. You add one to the scene and place it where you want to "slice" the models. Then you set the camera up so that it looks through the section plane. In the section plane parameters you have an option to either cut completely or have the cut off part be more like a one way where it still reflects light and is visible from the inside.
ciao
TD
edit to add: the effect of the section plane is only visible in Iray preview or render. Just avoid any confusion.
The option to reflect light (and block incoming light) is the Clip Lights check box.
Thanks, I wasn't at the computer and could not remember the exact name.
thankyu
Sorry, I don't understand. I use IRay section panes quite a lot to let light through for interior scenes (actually that's most of my scenes). But the OP question seems like a contradiction to me - if light is being reflected (light bounces) then the ceiling (or whatever is in the path of the light) is not invisible. There is some measure of opacity there. I'm confused by the responses suggesting this is not a contradiction??
No, it's not any contradiction. A section plane can make the part it cuts off either completely invisible or it can make it "see through" from the camera side but opaque from the other side. An example is a small room with a mirror. With the section plane and cup lights checked you can have the camera outside the room, see through the wall across from the mirror but the reflection in the mirror would still show the wall.
ciao
TD
Well, that is certainly news to me. Thank you for the explanation (although I'm still not sure how it works).
Thank you @thd777 and Richard.
I didn't know the section plane could reflect the lights. Always more to learn.
@marble Here is a quick illustration of how it works using Hole's Onyx Bed and Bathroom as example: The first image shows the side vioew in wiremesh. You can see that the camera is in the bedroom pointing towards the wall (where the move tool is). The section plane is just behind the wall between bed and bath. The second imgae shows the view of the camera in texture shaded mode. You see the bedroom wall. The third image shows the iray preview with "Clip Lights" on the section plane OFF. You see the mirro shows the sky dome because everything in front of the section plan is cut off and invisible. That last image shows the same view with "clip lights" ON. Now you see the bathroom wall refelected in the mirror and the only light comes from the lamps in the bathroom.
Hope this helps
Ciao
TD
Yes, beautifully illustrated your point, thanks. I had no idea that was possible but I wish I had known because I've had to abandon or figure out work-arounds so many times.
Now, if you can tell me how to stop spotlights being reflected in windows and mirrors (no section panes involved) - I'll be an even happier old Hector.
@marble Not with regular spot lights. What I do in this situation is to use the Dishlight from Iray Ghost Light Kit One https://www.daz3d.com/iray-ghost-light-kit-one Scaled down it makes a nice spot light. Here is a quick example using Hole's Crystal Loft which has lost of mirrors. The first image has the dishlight pointed at the candles on the table. I have craked up the power way high to make the effect obvious. For an actual image one woul;d turn it down. As you can see neither the light source nor its reflection show up. The second image shows the setup with the dishlight having a white texture to illustrate where it and its reflection are located.
Ciao
TD
I do have that Ghost Light kit so I'll give it a try. I have not used it much because I find that DAZ Spotlights render much quicker in IRay than emissives - many times quicker in my experience.
indeed. Spotlights are definitely significantly faster to render than emissive lights. No doubt. But in some situations you can do things with the ghost lights that you can't achieve with standard lights. That's when it can be worthwhile to pay the price in render time.
ciao
TD