Hi all,

I'm really hoping i can get some help with getting the Houdini Camera to match the focal length etc of the real camera footage i have.

The footage was shot on a Panasonic SDX-900 with a 16x9 with an Anamorphic Lens (therefore the resolution is 720x576)

The camera is basically a 2/3" CCD, so for example, if I have the real camera lens set to 40mm, how do i set it up in Houdini to be the same focal length?

I have the American Cinematographer Manual at my side with conversion to 35mm, would this pull it off?

The Help section within Houdini offers some kind of equation, but to be honest im finding it all a bit confusing.

I'm also a bit confused about the pixel aspect ratio…ops:

Any help on this matter would be greatly appreciated.

here try this out [sidefx.com]
As far as I have scanned through his new camera it looks like it might help u out.

cheers, ill give it a go and let u know what i think

whilst this script is really really useful and in my opinion improves the Houdini cam greatly, it doesnt really solve the issue im after, which is converting the focal length measurement from 2/3" CCD to an equivalent value that i can use in Houdini

but thanks

Hey! thanks for plugging my Camera script

As for your camera issue, you need to plug your film back width into the aperture parameter on your Houdini camera. If your focal length is in millimeters then your aperture has to be as well. Not sure if the 2/3“ is a truely accurate measurment of the film back width, but it may get you close. 2/3” = 19.9333333 millimeters. Look through your camera manual to see if it has any info on the film back width (or something similar to that)… or try to track a shot using a good match moving software and it should spit out the proper values for you.

As for your pixel aspect ratio, it's going to be a ratio between your resolution and your screen aspect ratio, something like576/720)*(16/9)I could totally have the order of the division messed up (I'm funny that way), if it doesn't look right play around with a variation on that.

BTW: Did you know you can get conversions using google? Try the following in a google search.2/3 inch in mm

Also… if you like my Camera Creation Script, rate it up!

The footage was shot on a Panasonic SDX-900 with a 16x9 with an Anamorphic Lens (therefore the resolution is 720x576)
………
I'm also a bit confused about the pixel aspect ratio…

Since you're coming out with that res, I am assuming you are shooting PAL..So in that case, standard d1/dv pal footage will have a pixel aspect ratio of 1.07 and the standard d1/dv pal pixel aspect ratio for 16:9 anamorphic is 1.42.

Personally, i render all 3d out in square pixels (1.0 pixel aspect ratio). Anything created from a computer should always be done in square since that's just how it works: pixels are pixels. The DV standard screwed with this by keep resolutions the same and “squishing” the footage at recording and “un-squishing” them at playback. That's how your 4x3 and 16x9 footage from your sdx-900 are both 720x576. Your 16x9 is just squished horizontally more, hence the 1.42 pixel aspect ratio.

So yea. Do all your 3d at square pixels and then at your compositing phase, deal with your mixing and matching of pixel aspect ratios.

Alright! That confirms that my expression works(576/720)*(16/9)=1.422222Thanks!

But… I must disagree with rendering at square pixels when your plate is anamorphic. In order to get the best match to your photography your CG should be treated in the same manner as your source material. Anti-aliasing is going to be different if rendered anamorphic or square pixels, and you want to keep from scale filtering as much as possible to ensure the integrity of your image.

Most of my work has been in the Commercial Industry NTSC .9 aspect ratio, and for over 12 years I've never met anyone who would consider rendering their images with an aspect ratio of 1 then scale it down in Y to match the plate. Also, when I was working at Sony, we rendered anamorphic aspect to match the plate… it is the right thing to do.

But… I must disagree with rendering at square pixels when your plate is anamorphic. In order to get the best match to your photography your CG should be treated in the same manner as your source material. Anti-aliasing is going to be different if rendered anamorphic or square pixels, and you want to keep from scale filtering as much as possible to ensure the integrity of your image.

Most of my work has been in the Commercial Industry NTSC .9 aspect ratio, and for over 12 years I've never met anyone who would consider rendering their images with an aspect ratio of 1 then scale it down in Y to match the plate. Also, when I was working at Sony, we rendered anamorphic aspect to match the plate… it is the right thing to do.

Jeff,

Your thoughts here are well said and I actually have to agree with you whole heartedly. That all makes perfect sense. Unfortunately, my comments more so come from my own very limited experience (23, recent graduate, 2 years professional experience) in the motion graphics industry. Every professor (i know not extremely reliable, but hey, it's what we had) as well as all the people I've worked with in the MG industry have all done it this way. Create in square, comp with live in non-square (NTSC .9 here as well). But your opinion holds a very logical backing. Will have to take this approach from now on.

Thanks for the refreshing viewpoint,
Dave

ops: Sorry, if I came over a little strong Dave, I pulled an all-nighter last night and am a little on edge. Just re-read my post, seemed a little harsh, not my intention.

Always glad to offer a little insight though. I worked with a guy for several years that was particularily anal about this kind of thing, used to drive me crazy (love ya Denis), and a lot of it rubbed off on me… I'm sure he'd be proud :'{

I was just talking to someone else on that subject and he said a lot of people render that way… not sure if they know something I don't, but it just don't seem right.

Take Care

I'm on the same page as Jeff. I've always rendered everything with the same aspect ratio as the plate.

Cheers!
steven

jrwillette
Also… if you like my Camera Creation Script, rate it up!

ratings are for kids … just kiddin
Btw how did u achieve to have whose fancy little handles when u look thru your cam?

Jeff

Thanks so much for solving so many issues I have been having!!

So, just to check I've got this right - as it was a 2/3 camera, I assume if I put 19.9333333 into the apeture parameter, then tap the focal length I was shooting at (for instance 120mm) into the focal lenth parameter it should match up?
With it set to 16:9 PAL Anamorphic too, of course. :shock:

I've been busy buzzing round getting ready for my latest project, so I didnt take the time to rate your camera, but as I get to give you the message in person - BIG THUMBS UP

Maybe you could add something to it that would help with the kind of ‘real-world’ lens issues i've been having? ops:

I've already been telling everyone here at Bournemouth Uni to make sure they download it. The word has been buzzing round our studios, and its all positive.

Thanks a lot, ill be sure to post back if i have any more problems

J

JohnnyBGoode
Thanks so much for solving so many issues I have been having!!

So, just to check I've got this right - as it was a 2/3 camera, I assume if I put 19.9333333 into the apeture parameter, then tap the focal length I was shooting at (for instance 120mm) into the focal lenth parameter it should match up?

No problem, I learned a lot of that making the Camera Creation Script. Glad to help.
Yes, it looks like you got it. In theory it should match up, but there are many other factors involved; the accuracy of the CCD (the image may only take up a portion of the CCD so the 2/3" might not be correct), Lens curvature, among other things. It should get you close though.

keltuzar
Btw how did u achieve to have whose fancy little handles when u look thru your cam?

Sadly, I cannot take credit for those handles, that is all SESI. Many of the stuff that my camera network does can be seen while interacting with the camera in the viewport. If you right click on the camera in the viewport you can turn on frustum and focal length, and other cool stuff. My camera just allows you to see those things all the time, but not interact with them, it's all tied to the exsisting controls on the default camera.

JohnnyBGoode
Maybe you could add something to it that would help with the kind of ‘real-world’ lens issues i've been having?

Not sure how to do that, I think you can add custom items to the defaults menu, but that would be about it.
I guess one could make a Digital Asset that encompassed a camera, then you could add a whole slew of things. That is a project for another day.

stevenong
I'm on the same page as Jeff. I've always rendered everything with the same aspect ratio as the plate.

Thanks for the reassuring BTW: forgot you thank you for welcoming me back to the Houdini Community on another thread. I never left Houdini, but I just dropped of the list for a while… Now that I'm working freelance I figured it was a good way to get my name out there again