How? Make single object rendered from canvas look exactly the same as if rendering the whole scene?
vozolgant
Posts: 207
I have a room scene with chairs in it. When rendering the entire scene, without using Canvas, everything looks fine.
But, if I render a single chair in the scene using Canvas, the chair render looks different vs when rendering the whole scene at once. Why is this?
How can I render a single object in the scene using canvas without its look changing?
Take this room for example. How would I render picture frame on the wall into a separate alpha layer that can be overlayed in photoshop, but have it look exactly the same as in the original image; of which the entire scene was rendered?
Another problem, how do I preserve shadows?
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Select the item you want to isolate, create a beauty canvas using selection, check the Alpha box, and then do a spot render to a new window (Option in Tool Settings) including only the object. Don't change anything about the scene.
Imagine you have a DAZ scene of a: Room with a floor, walls, window, chair inside room, HDRI light for outside, and a point light inside the room.
Now, imagine you render the ENTIRE scene, calling it: Room&Chair.Tif
Now, imagine you hide the chair and render the entire scene again, calling it: Room.Tif
Now comes the stupidly hard part. I want to make the chair visible, and ONLY render the chair and whatever shadows it casts, into a transparent file called: Chair.TIF. Then, when I overlay Chair.TIF over Room.TIF on photoshop, it should look EXACTLY like Room&Chair.TIF
Can any brave soul actually manage to pull this off and explain how you did it? I know the basic use of canvas, but I cannot manage to do the above. I can't figure it out.
The individual blanket render doesn't have the shadows saved.
Your second render is of the entire scene, including the couch & blanket, which has all the shadow data.
If you rendered your scene without the blanket, then overlaid your current blanket render, it wouldn't have any shadow data saved, and it'd look way off.
Merged threads
Too bad I can't delete threads. I wanted to delete this one and let the other in Commons be seen. *sigh*
Could you delete this one and let me remake it in commons?
You can move it into The Commons yourself - go to the first post of the thread and click on the cog near the top (on the title line), select "Edit" and there should be a drop-down list where you can select in which forum you want the thread to be.
You mean like this?
Yes, but with all the white background transparent.
If you're able to do that, can you explan how you did it?
If you're using the Matte enabled setting on the ground, the problem with that is it catches shadows from EVERYTHING.
I don't know what the correct methodology is to create something like this:
- ROOM.TIF (Background)
- CHAIR.TIF (transparent, but with correct shadows preserved in the tif file)
- TABLE.TIF (transparent, but with correct shadows preserved in the tif file)
- PLANT.TIF (transparent, but with correct shadows preserved in the tif file)
Then in photoshop I load Room.Tif, and overlay Chair, Table & Plant TIF files, and the entire scene should look exactly as if I did a complete render in DAZ Studio, but in actuality, I'd use canvas to separate the objects into different TIF files, with all the correct shadows preserved.
I cannot figure out this methodology. There's an issue of overlapping shadows that's a bit confusing as well. I might just be better of using the spot render tool.
The background is transparent. The dark areas are ambient occlusion from environment lighting. It is done with the matte setting, and a beauty canvas with ground and stool as node selections and the alpha channel enabled.
Unfortunately this doesn't work in any of my real production scenes. If I enable matte on any type of ground: carpet, wood floor, ... it produces bizarre shadows when beauty canvas only has the ground and chair selected; with alpha enabled.
Try adding objects next to the chair, and you'll begin to encounter the problems I'm having.
Saving an object/character plus shadows (by the way, you may also want any reflection interactions between the object/character and environment for real accuracy) is incredibly difficult in Iray, and, IMO, not worth the effort. Yes, you can fake it using the Iray Matte function or the Draw Ground function in the Environment tab, but both of those are faked shadows and not real raytraced shadows from Iray. According to the Iray Programmer's Manual, "Iray Photoreal cannot render the shadow canvas". There is also not even an "Ambient Occlusion" canvas, which again is just faked shadows.
Add to that the fact that the Iray Matte function doesn't seem to work with what I assume most people use for lighting, which is Emissive light sources.
Personally I've given up on the thought of isolating a character/object and shadows from the background/environment, and instead focus on adjusting individual light sources (hugely useful, IMO) and other types of post effects. Yeah, if you want to place a character over a background image or HDRI you can use "Draw Ground" to get a faked shadow, but I'd rather use a real ground plane and get raytraced shadows.
Regarding reflections, yeah you may be able to write a Light Path Expression (that does seem to work), or fiddle with Iray Mattes to get something, but personally I think it's more effort than it's worth.
Now you can isolate just an object/character or group of objects/characters with a transparent background (using the Nodes function with a Beauty pass and Alpha), but that won't provide any shadows.
This is the same conclusion I came to. DAZ is limited in this regard. Not a big deal, but it would've been nice to be able to render a background, and foreground objects into separate files with shadow preserved.
I basically use the spot render tool which works out okay.