z-buffer from the target

[flino2004]

I was wondering if it would be useful to have vray z-buffer controls from the Target camera instead from the camera. starting x meters before and after. I think it could be very useful.

Fernando

[vlado]

Hm, I can see where it can be useful... does anyone else think so?

Best regards,
Vlado

[flino2004]

Having both option would be a Plus, ..the target point is the focus so you can always have "zero" before the target or fading it with a distance.....The DOF effect would be easier to setup or control it taking the target as reference in some situations.
Or even a hybrid solution using both information from Camera and Target so in one shot you could get the blurry effect for objects close to the camera and far way as well of the focus(target).

[vlado]

Ok, I've entered this as a feature request. The way I see it, this would come as a checkbox in the ZDepth render element; if enabled then the min/max zdepth values are measured from the camera target (so you'd need to enter values liks -100 and +100 for example to get the zdepth to be black 100 units before the target and white at 100 units after it). Does that sound ok?

Best regards,
Vlado

[flino2004]

Let's say white is sharp and black is blurry...so it would white from the camera to the point before the target(this distance could be "0") and from this point starts getting black(gray) to the point after the target, so after this point is Black, Right?
or taking the target where the white starts and fading to black to both points?

Fernando

[vasil.minkov]

Hi,

I need some clarification on this feature.

Here is the current situation:


As far as I understand, these are your suggestions:

Vlado's suggestion:

It's drawback is that the camera clip boundaries aren't usable with such implementation.

flino's:

The last suggestion is a bit tricky - the focus distance should be between zdepth min & zdepth max. It is not clear what shall be done if this is not the case:


Also, I am unsure how to name the option - e.g. "focus relative", but it is a bit ambiguous.

What do you think?

[flino2004]

What I suggested is more like the 3rd graphic, so the pure white spot is the target and fade to black to both points, so it's like the real camera situation, right? if somebody wants blurry after the target and sharper from the taget to the camera the minimun amount should be -x being x closer or the same amount units from camera to target......Using this diagram (3rd), you can easy animate the target and get very nice effect with the correct Z-buffer per frame.
Using the target, one can get better DOF effect from a visible known point (target) and the standard z-buffer still can be used and even combined in post if needed or for fog effect.
If Chaosgroup integrate it with vraycamera of course the target could be override it using "specify focus" or even having another option to match the real DOF effect in vray camera for post....when you don't select DOF in vraycamera option you could get in vrayelements.

Fernando

[LarsSonparsson]

I see no point in z-pass that fades from black to white and back. All dof plugins are designed to work with normal depth pass - black to white.

I like Vlados idea, connecting min and max radius around the camera target. So if setting distances: min 2m and max 5m, it would create z-pass starting 2 meters before target and continuing 5 meters behind it.
That could help a lot in those situations, when you are doing dof in post and need to have some moving object in perfect focus all the time. You can do that in post by animating the focus distance, but sometimes it can be quite tricky. I'd prefer to animate target distance in Max and generate z-pass based on it.

[flino2004]

the idea of the z-buffer from the target is simulate real camera behavior in post, focal point is always sharp and the rest has a blur in some degree, It could very subtle or very extreme...In my opinion, if you take the reference point different from the camera then it will go black-white-black....if you want more control of the focus then a third parameter like a radios from the target is needed to extend the white area.... otherwise how you can create this effect with a standard Z-DEPTH?
http://www.dofpro.com/gallery/dofpro_barrelsDOF.jpg

....Maybe I'm wrong, but how the real cameras work? if it works like Vlado's suggestion It's like that.
about the DOF plugins they read the colors, it doesn't matter if it's black-white or black-white-black, they will do it anyways!

[LarsSonparsson]

"otherwise how you can create this effect with a standard Z-DEPTH?"
No problem for any of the dof plugins I know. When doing dof in post using z-depth, you can set the focus distance (the point of grey level in z-pass), that will be in focus. All the rest front and behind starts to get blurry, like in your example. If you have any compositing app, you could try that your self. Composite, that comes with Max 2012 has good lens blur. Even in After Effects you can do that with Camera Lens Blur.

Edit

"about the DOF plugins they read the colors"
Nope. Even in Dof Pro page they say it.

"A Depth Map is a greyscale image where the grey level at any given point represents the distance of the object from the camera at the same point in the original image."

[flino2004]

Lasse, I think the point of the "target" is that you don't have to "find" the gray to be in focus... the target is in focus already, so in your DOF plugin you control how much blurry you want the rest of the image.....vraycamera does the same if you don't override the focal point. am I right?

Fernando

[flino2004]

I posted this wish some time ago, I was wondering if Chaos would use idea as a feature?

[vlado]

We started working on it, but we weren't sure whether we are doing it right. If you can suggest some way for us to test if we do the correct thing, it would be helpful.

Best regards,
Vlado

[flino2004]

graphic

I don't know exactly but this is more less what I have in mind.

All the distance are taken from the target of course..and maybe as part of the values if you put -1 in Mn, white starting fading from R to the camera.

so the input values are R,Mx & Mn.

Thanks,

Fernando

[vlado]

Ok, that's a bit clearer. Hopefully we'll get to that soon.

Best regards,
Vlado