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Dalaran AW
09-01-2004, 11:15 PM
Hi there,

I am using Maya 6 and want to know if its possible to render with MR in fields. I tried stuff like in the command line renderer: -fields 1 -pal .But that doesnt work because it doesnt recognize those commands.

Does anybody knows how to turn this on and if not, does anybody had another solution?

Thanx,
Dalaran AW

mthemelis
09-01-2004, 11:53 PM
i knew for maya 5 that you needed mr stand alone to render in pieces.

sorry...

(if someone knows something more, please shed some light on this one!)

courte_manche
09-02-2004, 07:24 AM
Set "50 fps" in your animation setting or replace "1" by "0.5" at side "By Frame" in your render global setting, you've got the same result, having twice more frames for your animation.
and then, create field frames in a compositing software.

Dalaran AW
09-02-2004, 09:48 PM
Thanx guys for your replies...

So there's no flags or switches to turn it on in Mental Ray... mmmhhh thats odd... a lot is used in television... and there they use fields all the time....

Gonna the try 0,5 method it right away... :)

Thanx,
Dalaran AW

Goon
09-02-2004, 10:53 PM
Why aren't you doing it in post? It might not be as good as rendering out actual frames, but I doubt it will be very noticeable, plus you don't double your rendertimes.

Dalaran AW
09-02-2004, 10:58 PM
He Goon...

So you mean just render it out normal with MR... and after that in a compositing package do the fields...?

We use afterfx and digital fusion... are those package capable to do that proper?

Thanx,
Dalaran AW

leuey
09-03-2004, 03:20 AM
uhhh, to do it in post you do have to double your rendertime. To get fields you have to interpolate from 2 different frames. Rendering out say 90 frames at 30fps and running it through AE (or another compositing program) to get 3 seconds of ani with 'field rendering' checked won't do you anything.

RE:Vision fx has some good plugins - you could use Twixtor to double your frames then use re-interlacer to created fields. I've done it but it doesn't look quite as good. So yes, unless there is something I'm not aware of you DO have to double your rendering (by .5 frame or double the fps - just hope you don't get an error during rendering b/c it's hard to figure out where it left off...)

oh yeah - and it does suck that there isn't a field rendering option in MR.

-Greg


Why aren't you doing it in post? It might not be as good as rendering out actual frames, but I doubt it will be very noticeable, plus you don't double your rendertimes.

Goon
09-03-2004, 02:43 PM
I've never needed to render fields in post, I've just output straight to video, and it has appeared fine. I haven't noticed strobing or anything.

Maybe I'm missing something, but my thinking was simply that film cameras do not record at 60 fps and display just fine on a tv. How much work has the studio had to do to ensure this?
My understanding of fields is simply that they are two interlaced frames, normally from the same frame. If you render out fields with offset frames you will get smoother movement, but other than that, why would you double your render time?

I'm probably just exposing my ignorance here, it just seems unneccessary.

alexx
09-03-2004, 03:12 PM
for most of the aminations i do fields are indeed not needed (i usually only work for tv).
you can run into trouble with vertical lines that move fast from one side to the other like columns of a building.
but since fields are a real pain in the ass if you want to do a lot comping with your renderings i rather accept a little strobing than going for double rendertimes.

what you can do not have to render fields is using a good amount of motion blur. that does the job quite well. but i would render the blur seperately using the blur2d.exe or the tools that MR offer (which i dont know, but i know they are there :)
like that you can adjust the needed amount easier and faster.

lets all hope hdtv is coming faster: 24p

cheers

alexx

leuey
09-04-2004, 07:31 AM
Well, it's kind of your call but I pretty much always render fields. I've had unusable strobing w/out it. Lightwave handles it a lot better than Maya (I've had field problems w/ the standard maya renderer - and the MR route is double render-time.) If there's not a lot of motion you can get away w/ it. Typically I would render fields & motion blur if you have the time. Sometimes it's faster to render 60fps, interpolate to 29.97 fps w/ fields than it is to render 30fps w/ decent mo-blur.

Definately check out RE:Vision fx website. They have re-interlacer tools, time-remapping and mo-blur as a post effect (using rendered vectors from the 3D app) filters.

best,

Greg



I've never needed to render fields in post, I've just output straight to video, and it has appeared fine. I haven't noticed strobing or anything.

Maybe I'm missing something, but my thinking was simply that film cameras do not record at 60 fps and display just fine on a tv. How much work has the studio had to do to ensure this?
My understanding of fields is simply that they are two interlaced frames, normally from the same frame. If you render out fields with offset frames you will get smoother movement, but other than that, why would you double your render time?

I'm probably just exposing my ignorance here, it just seems unneccessary.

zuao
09-04-2004, 10:38 AM
If I had to do fields (and of course there are cases where you have to do this, even if you don't like it ;) ) and if I had time and renderpower I would prefer the method of doubleing rendertime, because you could take advantage from this at the compositing stage.

But why not doing it this way (it's obvious):
In the Renderglobals put your settings as usual.
But set "By Frame" to "0.5" and add "0.5" to your "End Frame"-value. Change the resolution height to half the size (Don't change the Aspect Ratio).
Go to your favourite compositing weapon and have fun to interlace. In my case I'd go for Shake, get my image seq, set the increment to "2" and duplicate it. For one I offset the firstframe by 1 and connect both to the interlace node, turning on "merge"-mode and set the field order as needed. that's it.

have a nice weekend,
nando.

mrgoodbyte
09-04-2004, 07:25 PM
Always render to whole frames. This means progressive. No fields. Computers handle progressive way better than interlaced simply because computers are progressive image displays.
Zuao mentioned Shake. Shake doesn't handle interlaced footage very well. Imagine the terrors of rotoshaping interlaced footage! After Effects on the other hand will do a better job in this because it handles interlaced footage internally.
In your case, Dalaran AW, and all you PAL people out there it's my experience to render to 25fps progressive, do your compositing work and process that progressive output into fields using your encoder when outputting to DVD. Personally I like to use TMPEGenc. If you're recording your footage on your VCR, which is connected to your TV-out of your graphics card you should check the specs of your card. Some cards will handle the conversion to fields from progressive automatically.

For you people in NTSC-land I'd say render in 24fps progressive. Composite your stuff in progressive mode and encode to 29.97fps using an interlaced 3:2 pulldown setting. As for direct ouput to VCR your graphics card *should* handle the conversion to fields and perform the 3:2 pulldown internally and pose no trouble.

-Ronald

Dalaran AW
09-04-2004, 11:17 PM
He guys... thanx for the huge replies... seems that this area is still not clear to a lot of people... so thanx for helping out.

Allrighty... I rendered out my frames with the "By frame 0.5" method. So whats next... for example Digital Fusion has the 'fields' node... but wants 2 inputs... how does that work... or is it easier to do with AE?

Is there btw a huge difference between 'interlace' and 'fields'? Or is it the same? And how bout odd and even fields? Sorry for this noob questions, but I always used the standard renderer and always took the easy field option for granted... Now I get interessested...

Greetings,

Dalaran Aw

Dalaran AW
09-04-2004, 11:23 PM
ps

I rendered without mblur... because it took ages to render with MR. I want to do it in post... any suggestions wich package handles that well?

I saw alexx mention the blur2d.exe tool... whats that? is that Maya?

Greetz,
Dalaran AW

mrgoodbyte
09-05-2004, 03:05 AM
Not entirely sure about Digital fusion but my guess for the fields node is that one input is for the even field and the other for the odd field. I wouldn't do it in AE since it handles interlacement internally so getting it right can be quite tricky.

For 2d motion blur in post look at this thread: http://www.cgtalk.com/showthread.php?t=136510
Yes, blur2d is a Maya application. It takes motion vectors stored inside an IFF file and applies it to the image also stored inside the IFF.

Interlaced footage contains 2 fields: Odd/upper/top/A and even/lower/bottom/B. Yes, the 2 fields each have 4 different names. It's which field gets projected first on the tv. PAL is upper first, NTSC is lower first.

-Ronald

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