Streamline backplate integration workflow

[^Lele^]

From my setup, all you need to do is turn on receive GI, and add the ground to the exclude list for illumination in your dome (while it'll correctly shadow with it.).
No dark outline on lit backdrop.
The last image is what you got without excluding the plane from the dome illumination.




As far as the

crazy OverrideMTL hack

goes, that's technically called "ray-switching", and it's a requirement, if your geo isn't always a flat ground plane, Z-up (in max), and all you ever do is packshots (cfr. vRED).
It's there for flexibility.
I only switch away from the diffuse material to a lightmaterial where i do not want the lighting to influence my reprojection (i get no shadowing on a vraylightmtl), but have a shader with the repro in the diffuse map slot for the base.

In regard to multiple camera projections, well, cameraMapGemini is the go-to plugin, and has been for many years (and i talk of VFX with super complex stereo reprojections on tracked, animated cameras...).
Expensive, but for those wishing to, or having no other choice than, resorting to the dirty trick of camera mapping, that is a must.
I *think* V-Ray provides for enough material to do this stuff the right way as it already is, the rest is up to user ingenuity, or choice, in this specific case (ie. script your way out of it, or buy a plugin to do so for you.).

just my 2 cents, though.

[LudvikKoutny]

Hi,

I am very familiar with concept or RaySwitchers, but they should by no means be necessary to get correct matte/shadow material functionaliy, regardless of matte geometry orientation.

As you can see, name of this thread is about streamlining a process that already takes a lot more annoying steps than it should, while your workarounds actually introduce even more steps to already frankly ridiculous process. Things like this should just work, especially in expensive renderer like V-Ray. With pretty much any other mainstream renderer, I can set up backplate integration in very few simple steps without any hassle and workarounds.

This is what happens when I enable Receiving of GI on the ground plane and then exclude it from dome light illumination. Shadows turn weird shade of orange and blotches start to appear in the contact areas:


I am looking for a simple and correct solution here, so why just not admit that this should be improved?

Edit: By the way I was not talking about multiple camera projections. Just about switching backplates and rendering the object from different angle. For example if you buy a set like this: http://hdrmaps.com/hdre/nature/grave...of-river-drava

It's one HDRI from one place, accompanied by a bunch of backplates. And you want to use it to render car from multiple angles, like in this case http://raw.bluefile.cz/?p=457

In V-Ray, you have to do quite a few steps when you change cameras and need to switch backplate. Regularly, you just change camera, switch backplate to one that camera is matched to, and rotate HDRI to si matches backplate angle. Since V-Ray does not correctly project backplate set to "Screen" environment mapping mode for all ray types, then you also have to use Camera Map Per Pixel map to truly project that backplate on top of the geometry. But Camera Map Per Pixel map does not automatically set camera to active one each time you change it, you have to manually pick it. It's a tedious process, and often you can miss it, and then notice something went wrong only after you finish rendering, and notice something about reflections is quite odd.

[^Lele^]

I am very familiar with concept or RaySwitchers, but they should by no means be necessary to get correct matte/shadow material functionaliy, regardless of matte geometry orientation.

Oh but they should.
Insofar as the stuff you treat as matte is a ground plane, you can force ray switching of the best sort for that specific case: your matte object will never serve any other purpose than designed.
But if i'm matting out a tree in the middle of a grassy field, i really won't want to care about GI emission, nor reflections of the tree on the grass, and will switch to a correspondingly simpler set of shaders.
Next to the tree is a rock which i only see reflected in the pond, so its matting setup has to be different still, and so on and so forth.

When you're starting to matte out complex, interacting geometry, you want to precisely govern what each ray sees, for directability and performance reasons, so no, V-Ray shouldn't automate a thing, for camera reprojection and matting is among the most specific, and user-interaction intensive, CG tasks.
In fact, in my very simple setup, you could have walked away with a single shader without issue: the setup with the override was to show you how it's generally done when ray-switching has to take place, and further, how i went about creating it after reading your task description: override line by override line.

As you can see, name of this thread is about streamlining a process that already takes a lot more annoying steps than it should, while your workarounds actually introduce even more steps to already frankly ridiculous process. Things like this should just work, especially in expensive renderer like V-Ray. With pretty much any other mainstream renderer, I can set up backplate integration in very few simple steps without any hassle and workarounds.

This is why i was very confused: the thread title said one thing, reading through it, it seemed you were claiming V-Ray was just unable to do what you wanted.
However, the V-Ray tools are perfectly labelled, not to mention suited, to do this type of job, as far as i can tell, and work as intended.
They have done so for so many years, and so many people aside from myself, i was taken quite aback by your claims.

When you say "a lot more annoying steps than it should", you're being quite arbitrary, without a very precise proposal for an alternative workflow which however wouldn't disrupt everyone else's.
In other words, without precisely pointing out which required steps are wrong, why, and how they should be improved, there isn't much that can be done to help you (as i say below, the dome does work...).

This is what happens when I enable Receiving of GI on the ground plane and then exclude it from dome light illumination. Shadows turn weird shade of orange and blotches start to appear in the contact areas:
[ATTACH=CONFIG]27609[/ATTACH]

Well, i wasn't lying to you: it really works here.
Perhaps you're seeing the red material i used to illustrate GI bleed?
Try using just the base material in the override, given you don't need to see how ray-switching is set up.

I am looking for a simple and correct solution here, so why just not admit that this should be improved?

One shader, one camera repro, one object excluded from one light.
The setup is done, from scratch, in under a minute, and it works as you asked it to.
Explain to me simpler, or improved: i see no room for either, from the numerals, through the lexicon, to the class of objects used (ie. the very bare minimum needed, in the smallest possible quantity.).

Edit: By the way I was not talking about multiple camera projections. Just about switching backplates and rendering the object from different angle. For example if you buy a set like this: http://hdrmaps.com/hdre/nature/grave...of-river-drava
It's one HDRI from one place, accompanied by a bunch of backplates. And you want to use it to render car from multiple angles, like in this case http://raw.bluefile.cz/?p=457

You may not want to use multiple camera projections, but i see no other way, nor have i ever: can't really help you here.

In V-Ray, you have to do quite a few steps when you change cameras and need to switch backplate. Regularly, you just change camera, switch backplate to one that camera is matched to, and rotate HDRI to si matches backplate angle.

Whereas with my setup, you change repro camera, change repro backplate, and rotate the hdr to match.
It's max: all the backplate repro maps are instanced across the relevant shaders: change one, changed all.
So, once again, just how should this be made simpler, considering the light exclusion is done once, on scene setup, for the reprojected objects which receive GI, and every other step conceptually demands user interaction?

Since V-Ray does not correctly project backplate set to "Screen" environment mapping mode for all ray types, then you also have to use Camera Map Per Pixel map to truly project that backplate on top of the geometry.

Screen projection and camera mapping aren't the same thing.
There is nothing for V-Ray to fix in regard to screen mapping.

But Camera Map Per Pixel map does not automatically set camera to active one each time you change it, you have to manually pick it.

No it doesn't, how could it, through the currently rendered view?
Aside from the fact i may want to repro from a camera i ain't rendering from, it wouldn't know how to change the mapped image, so changing camera only would still make no sense.

It's a tedious process, and often you can miss it, and then notice something went wrong only after you finish rendering, and notice something about reflections is quite odd.

Well, i shan't comment on your task preferences or specific skills.

My opinion on the topic, for the little it's worth,is that it works as intended, it that isn't laborious at all, but quite straightforward, logically named/labelled and simple enough to template/merge/replicate.

[kosso_olli]

Let me know if this solves your issues.

[ATTACH=CONFIG]27595[/ATTACH] [ATTACH=CONFIG]27596[/ATTACH]

[ATTACH]27593[/ATTACH]

One thing that doesn't work, in none of the shown images here: The shadow cast by the objects doesn't get reflected in the spheres. That is bad.

Also, in the post from recon I can see the grey ground plane reflected in the spheres, I don't want that. I want to see the backplate reflecting on which the objects are standing on.

Take a look at the attached images and scenes, also check out the my post in the link:

http://forums.chaosgroup.com/showthr...572#post623572

matte_prob.zip

[^Lele^]

eh? I see the shadow.
And you really should have opened the scene: a 640x480 image is hardly forensic material.
And no provision whatsoever was taken for it not to show up.
No idea what you did in your scene: this has worked for years, you just have to learn to use it.
That's my take, brutally honest.

[kosso_olli]

It never worked from the beginning, when the matte for refl/refr parameter was introduced. I have multiple threads here regarding that problem.
Anyway, can you precisely list what I have to do in order to achieve what I am after? I just want to know how it is done right, I have no problem learning that.

[LudvikKoutny]

Oh but they should.
Insofar as the stuff you treat as matte is a ground plane, you can force ray switching of the best sort for that specific case: your matte object will never serve any other purpose than designed.
But if i'm matting out a tree in the middle of a grassy field, i really won't want to care about GI emission, nor reflections of the tree on the grass, and will switch to a correspondingly simpler set of shaders.
Next to the tree is a rock which i only see reflected in the pond, so its matting setup has to be different still, and so on and so forth.

V-Ray is only renderer on the market, that, according to you, requires manual rayswitcher setup for backplate correction to work properly.

...V-Ray shouldn't automate a thing, for camera reprojection...

Then why it already does so, but only partially?! If you enable matte object and enable matte for reflection and refraction, and you have screen environment mapped backplate, V-Ray will project that screen mode mapped environment background on top of the geometry which has matte enabled. But ONLY for reflection/refraction rays, GI rays are still being looked up in screen space? Either project it for all ray types or don't project it at all, what's the point of doing it half way, aside from confusing people?

However, the V-Ray tools are perfectly labelled, not to mention suited, to do this type of job, as far as i can tell, and work as intended.
They have done so for so many years, and so many people aside from myself, i was taken quite aback by your claims.

V-Ray's matte shadow solution was very immature even a few years ago, when I helped to push it into more usable state in this thread: http://forums.chaosgroup.com/showthr...onto-backplate

My suggestion were implemented and it pushed the solution lot close to production ready, but there are still these last two remaining issues before it's done right.

When you say "a lot more annoying steps than it should", you're being quite arbitrary, without a very precise proposal for an alternative workflow which however wouldn't disrupt everyone else's.
In other words, without precisely pointing out which required steps are wrong, why, and how they should be improved, there isn't much that can be done to help you (as i say below, the dome does work...).

I may be arbitrary, but my arbitrary opinion seems to be shared pretty much by everyone else who contributed to this thread, except you If you want precise proposal, here it is:

1, Fix DomeLight so it does not darken matte objects when GI is enabled. No additional steps, nothing. You just drop in DomeLight in scenes with mattes and GI enabled, and it will work. That's what everyone would expect.

2, When enabling matte mode already automatically projects screen mapped environment background on top of the matte geometry for refl/refr rays, make it project it for GI rays as well.

These are two very specific suggestions

Well, i wasn't lying to you: it really works here.
Perhaps you're seeing the red material i used to illustrate GI bleed?
Try using just the base material in the override, given you don't need to see how ray-switching is set up.

I did a mistake here. Your matte ground did not only have disabled receiving GI, but also matte for refl/refr. Once I enabled matte fore refl/refr, and did your suggested workflow (enable receiving of GI and exclude matte for Dome illumination), I've got even weirder result:


Here's the scene:
BackplateSetup2014.zip

Here's the link to HDRI I used http://illuminatedtools.com/Download...ckyard_CSP.zip

You tell me what's wrong, it's your scene and your workflow suggestion

One shader, one camera repro, one object excluded from one light.

Again. With other renderers - no shader, no camera repro, no object exclusion from lights. No workarounds like this, just purely functional solution.

The setup is done, from scratch, in under a minute, and it works as you asked it to.
Explain to me simpler, or improved: i see no room for either, from the numerals, through the lexicon, to the class of objects used (ie. the very bare minimum needed, in the smallest possible quantity.).

I guess I will just have to make a video showing how the workflow fails in production environment, I just wanted to avoid comparing V-Ray to other renderers directly as in this case, results would be devastating for V-Ray.

You may not want to use multiple camera projections, but i see no other way, nor have i ever: can't really help you here.

Whereas with my setup, you change repro camera, change repro backplate, and rotate the hdr to match.
It's max: all the backplate repro maps are instanced across the relevant shaders: change one, changed all.
So, once again, just how should this be made simpler, considering the light exclusion is done once, on scene setup, for the reprojected objects which receive GI, and every other step conceptually demands user interaction?

Already explained it above, again, I will just have to make a video

Screen projection and camera mapping aren't the same thing.
There is nothing for V-Ray to fix in regard to screen mapping.

I agree here, but why did Vlado a few pages back in this very thread said I should never use Camera Map Per Pixel map (camera projection map) with V-Ray's matte solution. Why does he mention here: http://forums.chaosgroup.com/showthr...ackplate/page3 that V-Ray does some sort of automatic projection (talking about case of screen mapped environment background)?

My opinion on the topic, for the little it's worth,is that it works as intended, it that isn't laborious at all, but quite straightforward, logically named/labelled and simple enough to template/merge/replicate.

I think your workflow is as much arbitrary as mine is. I do not know what kind of work you do, but you may just likely be less tolerant to weird/incorrect results, so you don't really notice many inconsistencies of your workaround. When you do highly photorealistic work though, every weird inconsistency matters.

[^Lele^]

But i have: there's a file, and ample debate.
I can't help in any better way, and from there stems the frustration you surely read in my previous post.

As i said before, matting is highly specific, and never, ever, a pleasant task, no matter the software.
Doing everything in one pass isn't always possible, and it isn't so for good theoretical reasons.
You are stating unequivocally that V-Ray is broken in this department, but what i see is confusion as to what is is specifically that you guys want, after having posted a file which does it all, correctly, and instructions to change the behavior of the matting.
Variations on the theme are nigh infinite (hence the ray switcher material and varied Vray and Object properties), and in any of the movies ever done with V-Ray, you can rest assured there's a heck of a lot of matting been done with it.
Not always in the one render pass, not always in the renderer, yet the goal has been achieved.

So the question remains: what attribute is it that a car on a flat plane has, which all other (successfully achieved with V-Ray by more than one person) matting excercises don't?
As such, what is it that V-Ray should cater for which it doesn't right now?
What ray path specifically should work differently?
Established that screen space projection isn't broken, nor is the dome, i mean.
Are you prepared to render more than one pass of your scene to get out the post-data you need to achieve the highly complex matting task you're after, should it not be possible in the one render?

Then, if that's the case, start a thread on the very specific matting issue you're having, post files, proper reports, and share as much clear info as you can.
The debate won't be on V-Ray being broken or not, but on how to best use the tools at the avail to achieve what is difficult to a specific (or specific set of) users.
And to me the approach change makes a lot of difference, creating room for a debate that in here, frankly, for me is exhausted as far as the original topic is concerned (or i have nothing else to add, at least.).

[^Lele^]

I didn't know of that thread, and it's a good thing you pointed me to it as Vlado told you much what i did, if in a slightly different way: everyone wants something different, the tools are all there, one needs to know what one wants very accurately, and then the workflow is quite obvious.
Automation is totally possible, and totally been done (by me for one, so i speak out of -multiple- first hand experience.), provided one's clear about the matting goals.
New matting needs? New matting setup.

V-Ray is only renderer on the market, that, according to you, requires manual rayswitcher setup for backplate correction to work properly.

Ray switching is necessary when you want to tell any renderer what to do with its rays, other than the usual behavior.
So, to get the plane to shadow and reflect, and participate to GI, you want a diffuse shader with your background reprojected on it.
However, the direct view should see a fully self-illuminated, background reprojected, shader.
Hence i use the VrayOverride material with two shaders, as described above.

Light exclusion, in fact, was a grievous mistake from my part, so i removed that.
And that's what my new setup (linked) sports.

Very nifty addition, that of the matte background.
Doesn't replace camera mapping for every other case where repro and render camera don't match, which are the body of the camera reprojection work outside of archviz and product design.
But it does at least negate the much hated (by you) camera map per pixel map.
So i took that out.

I now have nothing excluded, nothing convoluted at all.
Matte objects with one override material with two shaders in it, to match the requested behavior.
Vray properties set up so to get the shadows in the alpha channels for the matte objects.
The background map in both the shaders and the environment matte slot.

Operative setup time, from scratch, again less than a minute.

Try the file, see what you think.
BackplateSetup02.zip



edit:feel free to play with the override material and vray obj properties to achieve different results in different effects.
If you don't want to see the GI lighting of your mattes in reflections or refractions, for example, change the corresponding vray property.
Edit #2: in fact, i went ahead and did that, so to avoid further confusion, and updated the file.

[LudvikKoutny]

I've just opened your scene, did absolutely nothing to it except replacing the HDRI image, as I don't have yours. Then rendered it and I am getting exactly the darkening problem I am talking about.


I am again attaching a link to the HDRI map I am using http://illuminatedtools.com/Download...ckyard_CSP.zip so you can try yourself.

EDIT: The map was copied into secondary matte slot instead of instanced, hence the black reflections. Here's fixed version, but the problem still stands:

[jasonhuang1115]

This a fascinating thread and I have to watch closely. I don't necessarily mind if the setup is extremely simple but I recall in several threads here that matte object having issues with GI rays. In some discussions Vlado would simply mention that in order to get perfect shadow pass and perfect integration in post, you need to render the scene twice, no other workaround. Or there is the trick to bake your lighting to a perfectly white diffuse plane so you can use a diffuse mat for projecting the plate.

[LudvikKoutny]

This a fascinating thread and I have to watch closely. I don't necessarily mind if the setup is extremely simple but I recall in several threads here that matte object having issues with GI rays. In some discussions Vlado would simply mention that in order to get perfect shadow pass and perfect integration in post, you need to render the scene twice, no other workaround. Or there is the trick to bake your lighting to a perfectly white diffuse plane so you can use a diffuse mat for projecting the plate.

Actually, the compositing part of the workflow seems to be okay finally. Everything seems to be working right in that case. The problem I am having here is actually that workflow of rendering everything together (not comping it in post) is not working correctly now.

[jasonhuang1115]

Actually, the compositing part of the workflow seems to be okay finally. Everything seems to be working right in that case. The problem I am having here is actually that workflow of rendering everything together (not comping it in post) is not working correctly now.

Right, no issue in compositing whatsoever. I brought that up simply to emphasize that you can't get the result you want (perfectly correct integration with matte surfaces in one render) in one render.

Don't wanna dilute this thread without providing any scene or examples. I think we are heading somewhere if Lele is able to respond to your last posted example. The darker edge is an example where a trick (or in better way "some setup") needs to be done to ease out the transition to infinite dome/env, and to avoid a distinguishable "reflection line" on the door panel.

Wish I have access to Max and give Lele's sample scene a swirl.....

[LudvikKoutny]

Well even if there was some trick or setup to ease out the transition, it would still not change anything about it being wrong If client provided you with backplate, and that backplate would be darkened around the car a lot more than it should, then it's still a problem.

[^Lele^]

I do get the darkening with your map, Recon, but not with mine (or it's so faint i can't make it out even when heavily stretching the values...).

However, i think i have found a way out of your conundrum, with one render only (yay!) and no odd setups.

The plus is that we switch rays elsewhere, through the environment slots, so we don't need the rayswitcher, nor anything other than a black vraylightmtl on the mattes (or any other shader, for that matter.).
Another plus is that all it takes is to have nothing visible in the background (at rendertime only, ofc.), so no visible map in the environment slot, nor a visible domelight.
The backdrop map goes into the reflection/refraction and secondary mattes slot.

The main drawback is that the render itself doesn't show the background at all, so the direct visibility is all black for mattes and backdrop.
There may also be slight differences in the GI part compared to a straight render (without any matting, that is.): due to the forced decoupling of direct and indirect rays to avoid the double shadowing on the mattes, which i believe is what caused the darkening.
Again, you'll be the judge, i think this is correct, and the other GI result i was seeing was suffering as a result of the mattes.

The file is attached.
The result looks like this out of the renderer,

while a merge with the BG makes it look like so.


BackplateSetup03.zip