Z depth

[komyali]

Ok I am doing small animation of interior,so to save some time, I am using Z depth render element instead of vray deep of field DOF. Later in post process I will add DOF. So my question is what near range and far range to put? That depends on type of camera, because I want more photorealistic animation, image, what type of camera to use f number focus and other stuff, because I am not sure what is the best option? Anyway when you find what tipe of "objective camera" to use how to calculate Z depth near and far range? Is there a chart, calculator or something else? I want more calculated approach rather than my 6 sense

 

Edit

 

Ok I found calculator, but what is best parametars for interior shot (photorealistic)

Focal length mm?

Selected f-stop?

Subject distance?

Edited June 20, 2015 by komyali

[Nicolai Bongard]

Near and far range is to limit your gradient, so that if an object is never further away from the camera than 100 meters, you do not have to set anything higher than 100m in your far range. If you only have objects 100 meters from the camera but set the range to 200, your gradient will only use half the color range from black to white. However, if you set 100 meter in the far range and an object is 200 meters away, the objects from 100m to 200m will have the same color (100% black or 100% white), thus they will become equally blurred and that is not something you want.

 

Your last questions doesnt really make any sense, go for whatever looks good.

[komyali]

I know how Z depth work I rendered already everything tnx

I was thinking to be more calculated, but for best effect you have to have sense for estetics

[martinhoura]

then why do you ask? if you can't use your own judgement than I don't think anyone here can really help you

[Nic H]

if you multiply your f-stop by the total zdepth (in m) then divide by ISO you will get something usable - then in your comp program set the focus point to be at the mid point (128,128,128 if youre working in 8bit) then multiply the mid point (128) this by shutter speed to get the perfect zdepth pass for your scene. Works for me every time!

 

so F8 (8) x 10m scene = 80 / ISO 200 = 0.4 x 128 / 50 (shutter_ = 10.94m

 

give that a try. you will know your zdepth is correct when the range is from black to white and covers all of your geometry.

[komyali]

@martinhoura On the end I used my own judgement I asked before Offtopic where are you now? Every time I see a Afganistan I am in big dilema. Are you using different IP?

[martinhoura]

@martinhoura On the end I used my own judgement I asked before Offtopic where are you now? Every time I see a Afganistan I am in big dilema. Are you using different IP?

 

no it's just really nice here, it's summer now

[komyali]

I am really interested in Afgan. I meet some americans with Afgan roots. Afganistan was good place before russian and later american invasion. How is now there? Are you in CG?

[Francisco Penaloza]

I am a little confuse here, those formulas or links regarding "depth of field" are for real cameras, where if you change you F-stop and lens size affect the depth of field of your shot. In our CG world we can do this but also we can have way more control without physical limitations.

 

Your first question was "how to get a photo realistic effect". If you want that you should use the DOF in camera, not the post production cheat. Then and only then that math of F-stop and lens size make sense.

For sake of time or flexibility if you want to do it in post, (accepting the limitations that this will give you) then you only need to be concern of getting a nice gradient of all the area you want to control with your Z pass.

Everything else will be adjusted in post. Focus distance, spread of out of focus, amount of defocus, shape of iris, over exposure of areas out of focus or focused etc etc.

[komyali]

Yes but with DOF it is bigger time rendering. In post production you can have same effect if you have calculated distances good. I already rendered everything, you need to have sense for these effects.

[Nic H]

im still confused can you post a picture

dof isnt actually that slow in vray and pretty easy to set up

i think its worth trying both and seeing what the differences are

[komyali]

I dont think so, when you are doing animation, every second is important. I will test next week and post difference

[Nic H]

thankyou

[komyali]

You are right, it is not big difference in time, but in quality it is. If I crank it up with samples in DOF time would be proboably higher. Anyway I will always use zdepth because I have more controle with DOF later in post production, and if you use DOF in Vray when you finish and see some mistake you have to render it again. When I started using 3d, I was watching some video of post production and how animators use render elements. I was confused, and though it was better to get finished 3D from file rather than post product. I was wrong and later I found out how important render elements are, and later you have more controle over your finished render. So use zdepth