Vray DOF Problem

[dukey]

Hi all

 

I'm using vrayphysicalcamera DOF via the camera rollout (not the rendering rollout for camera). I have an object say 2 metres from camera and need the camera to blur out what is behind the object not what is inbetween the camera and the object (the object being in focus). So basically everything from the camera to the object to be focused and everything thereafter blurred. I'm stuggling to get what's directly infront of the camera focused.

 

Is this possible?

 

Thanks in advance!

[Boris Horosavin]

Hm, I'm sure there was a post regarding this issue few weeks back... (http://forums.cgarchitect.com/70203-vray-depth-field.html)

We were arguing about it: I myself think that Vray physical camera is too much physics oriented and very limiting in terms of tweaking and adjusting DOF affect (unlike Standard camera DOF which you can fine-tune from Render setup ). Somebody argued that you can get the right effect with the exposure control options, like simulating appearance of an actual camera, but it never worked for me because it ruined color and light quality I needed. Why there is no option to override Vray camera settings and tweak them from Render setup menu as you would do normally?- that's a mystery for me. I guess its because Vray Sun/camera system was too complicated to begin with (do you remember older versions of Vray? brrrr...) so they simply didn't want to complicate it any more.

So, basically, if you are not in for too much experimenting with Vray P.C., you can do it in post or turn away from Vray sun and try with standard camera (which is, in my opinion worst solution).

[Chris MacDonald]

Totally disagree with the above post. It is a joy to work with simply because it works as a real camera would. I have no interest in using a camera within max that isn't physically correct.

 

to OP: As long as you have your camera target on the item you want in focus; everything should be fine.

[Boris Horosavin]

Totally disagree with the above post. It is a joy to work with simply because it works as a real camera would. I have no interest in using a camera within max that isn't physically correct.

 

to OP: As long as you have your camera target on the item you want in focus; everything should be fine.

 

I didn't say it wasn't simple and I didn't say it wasn't accurate. But it isn't always effective either and that's a fact. 3Dcgi is to some point mimic of physical phenomena but just partialy. I simply like to have large amount of artistic freedom in my work which Vray Physical Camer DOF doesn't necessarily offer, and so do many other people. That is why the majorty of 3d artists I know still rather use post-prod. to achieve DOF effect (well, this and time saving factor, of course).

But as I said, if you are photography and physical accuracy buff you can dwell deeper into this matter than I was ready to.

Edited March 12, 2012 by Horosavin

[dukey]

Thanks for the input

 

Boris:

 

I guess you’re referring to VrayRayZDepth render element which I’ll have a play with and see if that improves on what I already have with regards to the blurred foreground

 

Chris:

 

I’m actually wanting to have the foreground and the target object in focus and everything thereafter in the background blurred out which doesn’t seem to be inherent in DOF as a general rule. The target is clear enough, the background is nicely blurred but the distance between the camera and the target (about 1 – 2 metres) is blurred out at the first 0.5 metres or so.

 

Cheers chaps!

[Corey Beaulieu]

Have you tried ticking the specify distance box and setting your focal distance from there? That plus a few other steps regarding a small F and short shutter speed seem to be the controls for camera based DOF.

 

Example 9 coveres the very basics of this: http://www.spot3d.com/vray/help/150SP1/examples_vrayphysicalcamera.htm

[dukey]

Corey hi..yes I've played with it all but the range of clarity doesn't seem to cover the distance I'd of ideally liked, seems it's limited as expected seeing as it mimics a real camera's DOF.

 

Thanks

[Boris Horosavin]

Corey hi..yes I've played with it all but the range of clarity doesn't seem to cover the distance I'd of ideally liked

Thanks

Yeah, I know exactly what you mean... Please send a feedback if you find satisfying solution, Zdepth included. Cheers.

[Scott Schroeder]

Not being sure what your scene consists of, but have you tried just rendering out two passes? One foreground and one background, then blur the background in post. You avoid all Z-Depth, and Vray DOF issues if you do it like this, given that your scene allows you to do this.

 

For example. Objects on a table. Render the table and objects out in one pass, and render out the background, ie everything you want blurred, in another. Combine to the two, and control the amount of blur you want in post by using a Gaussian blur or something like that.

 

If not, a separate Z-Depth pass is going to be the better solution as, again, you can control it in post. If you want things more blurred, or less blurred you can do that in real time in post. You can also adjust your gray levels and be able to slide back the blur point (at least to some degree and even more if you are using 32-bit Z-Depth images). If you need more foreground white in Z-Depth, start with a negative number and keep your two numbers (far and close distances) close to each other in terms of value. That will make the Z-depth transition of white (focus) to black (blur) almost instant and not give you the smooth gray falloff, which leads to the longer transitions between focused and blurred.

 

For the amount of time you are banging you head against the wall with the (settings + test render + repeat until satisfied) formula, you can save a ton of time doing your depth of field in post.

[Tommy L]

There is someothing alot more satisfying about capturing your DOF in render, but Scott's right. Soooooo much more controllable in post. Do yourself a favor and avoid the PS Lens Blur. Buy the DOFpro plugin from Richard Rosenman, you wont regret it. Uses ZDepth pass and creates excellent lens effects. Based on real world camera values but operates via sliders so you get realtime feedback on your effect.

[dukey]

Hi Scott, Tom

 

Thanks also for your suggestions. I’m a newcomer but will definitely look into what you’ve mentioned. The only problem I see doing it in post is that the background (decorative wall) falls away so it would need a gradient of depth to the blurring which has come out perfectly in the rendering, as you’d expect. It’s just that section at the bottom of the render that’s not desirable. Repeat until unsatisfied I’ve found a tut on the VrayZDepth so will give that a shot! If not I will look at Rosenham's plugin, cheers Tom!

 

Thanks again all

Edited March 13, 2012 by dukey

[Tommy L]

ZDepth DOF is a piece of cake. just make sure that the render element min/max distance is capturing everything.

Oh, and if you use an 'physically incorrect' DOF it can look really hokey. Which is what it sounds like you are going to do...

[dukey]

Tom, what gives you that impression re me using physically incorrect DOF?

 

When you refer to ZDepth are you referring to VrayZDepth in the render elements tab which is then adjusted in PS?

[Scott Schroeder]

Can you post an image of what you have so far? It's hard to tell sometimes from descriptions of what you have currently and where you want it to go.

 

I still have to agree with Tom, and my original response, that I think the z-depth element is going to be easier for you. Then if you have just a little spot in your render that may not be blurring right, just blur it in PS with the blur tool. The z-depth element will give you a gradient falloff, you blur based on the level of black. Pure white is in focus, and pure black is full blur.