Anamorphic: How to render

[Emery]

anyone?? :hmm:

[TomD]

Width: 720
Height: 480
Device Aspect: no need to input this (it should be 1.800)
Pixel Aspect: 1.2

check Lock device aspect ratio

In case you want to see what happens when changing settings. You can enable resolution gate (view > camera settings > resolution gate)

[lazzhar]

There is somthing wrong in Render Global as Emery said.
When I have to change the Device Aspect this Pixel ratio changes too. But this only with MR, so i switch to Maya Software
To solve that , then back to MR where I find it fixed.

[TomD]

Lazzhar,

You're right, here too. Hmmm smells like a bug looks like a bug. Maybe its a feature :scream:
I only tried in Maya software to render in anamorphic. But from my preliminary tests it seems your workaround works just fine.

[Jackdeth]

The other option is to un-squeeze your anamorphic footage to twice the resolution on one axis. And then render at that larger size and scale it down in the composite.

[jadamburke]

Guys it's not a bug.

You cannot change the device aspect ratio without also changing either the pixel aspect ratio or the resolution of the output.

When defining your outputs aspect ratio you either define the device aspect ratio OR the pixel aspect ratio. NOT both, since they are really just two different ways of setting the same thing: the Aspect Ratio.

Device Aspect ratio is the value that represents the total devices height/width. The pixel aspect ratio represents the pixels height/width.


The "Lock Device Aspect Ratio" checkbox will lock the device aspect ratio for when you change the image resolution (height and width), NOT for when you change the pixel aspect ratio.

Anamorphic a.k.a 16:9 aspect ratio is 1.778 not 1.8 (16/9=1.778)
This means that at a resolution of 720X486 (NTSC) the pixel aspect ratio is 1.2 Maya will set it automatically. You don't have to.

But Emery wants to output at a resolution of 720X480 (DV) The Anamorphic 16:9 ratio stays the same at 1.778 but the pixel aspect ratio is now 1.185 This is correct.

So Emry your settings should be

Height 720
Width 480
Device Aspect Ratio 1.778

Pretend the pixel aspect ratio isn't there because you don't need to change it because you already defined your aspect ratio via the Device aspect ratio.

[lazzhar]

>> You cannot change the device aspect ratio without also
>> changing either the pixel aspect ratio or the resolution
>> of the output.

Why jadamburke?

I always render pictures to 640X350 with pixel aspect set to 1 because this gives a square pixel, what's needed for a computer monitor. Using other aspect like 0.9 is for video output where the pixel is not square.
Device aspect is width / hight, we can use presets in render global but when you switch to MR you dont have the pixel aspect option so i've seen that going back to Maya software would fixe the problem.

[jeremybirn]

Device Aspect = ( (Width * Pixel Aspect) / Height )

You can't change device aspect without needing to change at least one of the other values to compensate, so the auto-updating you see is normal.

Yes, of course you're right that you should render 720x480 if that's what you're matching.

If its anamorphic video squeezed for widescreen playback from DVDs (see link (http://www.animemusicvideos.org/guides/avtech/anamorphic.html) ), then the Device Aspect is 16/9 (which is 1.78, or 1.777778 for however many decimal places), so you have 3 numbers in the equation:

16/9 = ( ( 720 * _ ) / 480 )

Now solve for Pixel Aspect and get a 1.1852 Pixel Aspect. (Edit - Sorry, you're right jadamburke - thanks!)

I think you can skip the lens squeeze issue, view your work normally, and just scale any image planes wider by 16/9ths for reference.

-jeremy

[jadamburke]

Its also true to say
Pixel Aspect Ratio = Device Aspect Ratio / ( width / height )

jeremy you made a mistake 1.778*480/720 = 1.185
The correct pixel aspect ratio for anamorphic 720X480 is 1.185


lazz,
a 640X350 image will have a pixel aspect ratio of 1.0 if the device aspect ratio is equal to 640/350 which is 1.828 If you set this in MR you will get square pixels.

just understand that if you have a 720X486 image with a device aspect ratio of 1.333 you will be getting a .9 pixel aspect ratio. Because 720 divided by 486 does not equal 1.333 it actually equals 1.481 so mental ray knows to make the pixel aspect ratio 1.333/1.481=0.9 because of the difference

A 640 by 480 image with a device aspect ratio of 1.333 results in square pixels because 640 divided by 480 equals 1.333 and your device aspect ratio is 1.333 so 1.333/1.333=1.0 or square pixels

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