Bojou-track to Nuke via Maya. Mismatch after Maya-export to .chan. =/

[NEO]

Heya.

Have some problems with a 3d-track from Boujou. I would add a lil movie to show the problem if it wasnt from the fact that I'm on modem at the moment.

I export the track form Bojou to Maya. In maya I add some dummy objects at some of the locators to see that the track really works ok. THen I use the maya-cam-export-gizmo from fxshare and export the camera to a .chan file. And I export all my dummy objects as .obj. In maya everything looks really good.

In nuke I set up a basci "3d-scene". I load the chan-file in the camera. The motion works and it looks ok at a first glance. Then I add a read-node and load my dummy-objects. Now, all of a sudden, the dummy objects doesn't sit as firm as they did in maya. It almost seems like there´s a different lens or focal length on my Nuke Camera then on my Maya Camera.

The thing is that I have used the same workflow in three different scenes and it is only on this one things go nuts. =( Since it all looks nice and solid in Maya I guess there must be something with the export to nuke or my setup in nuke.

I know it's pretty hard for anyone to give advice when I ain't attaching the stuffs, but as I said. On modem at the moment (yes, modems still exists =)). But maybe someone have some idea of what could be wrong so I try my luck here. =)

Also pretty annoying that the "integration" between NUke and Boujou ain't better. I mean like exporting directly from Boujou to Nuke or that Nuke could import the .ma directly. But I guess there are some inhouse gizmos for this. I kinda feel like what the big company see as a strenght in Nuke really is a weakness for smaller companies that doesn't have their own code monkeys that creates all those in house gizmos. =/ But hey, that was a little sidetrack and just me getting frustrated. =)

[maynard]

i only read the first paragraph but i think you need to check your camera angle, FOV etc..

il lcheck back later when i get a minute.

-c

[Mainframe123]

hi,

solve this problem with a script from fxshare.com or www.highend3d.com download this script and export the cam, works perfectly.........

[NEO]

Hmm... What do you mean now? highend3d and highend2d is now under the same roof, fxshare. And from there I downloaded the melscript i use for exporting maya camera to a nuke-readable .chan file. That is not the problem here. The problem is that one of the scenes I export ends up with a strange result in nuke. So the problem is not to get it into nuke but to get it correctly into nuke.

But you are maybe talking about another script? Please explain further what you mean. Thanks! =)

hi,

solve this problem with a script from fxshare.com or www.highend3d.com download this script and export the cam, works perfectly.........

[NEO]

Gona doublecheck everything now. Been in the garage and have been working on th ecar all day but now it's time to shape some 0's and 1's to something pretty. =) Looking forward for more input/feedback from you maynard! =)))

i only read the first paragraph but i think you need to check your camera angle, FOV etc..

il lcheck back later when i get a minute.

-c

[NEO]

Hmm... I went back and looked at those other tracks I made. And to my frustration I noticed that they also are incorrect. =( When I look at the scene in Nuke with the camera that has the imported chan-file and my dummy objects that I exported from Maya all looks good at the first frame. But as the sequence plays along the mismatch gets more and more obvious.

The script I use is this: http://www.fxshare.com/nuke/download...ters/4320.html

Is there some other script around that works better? Or have I stumbled across some 4.6 incompatibility?

I have started to look into what the mel script really does. And it does not seem to be that advanced.

How do you other guys move your cameras from like Boujou to Maya? And what workflow do you follow? You change something in Maya or Nuke that I have missed?

[NEO]

Some progress has been made, to say the least... =) The "problem" is acctually solved. I guess the problem was a combination of my n00bish and an undocumented/uncommented mel-script. After changing the roation order on the Nuke-camera from ZXY t o XYZ it seems to work as it should. =) That setting might have been to obvious or something because i started with looking on the filmback settings and the focal length.

I must also ask, what do you do with those parameters? Do you manually change them to what boujou or maya says or do you leave them at their current settings? The focal length seems to undergo some kind of conversion when it's imported with the chan file. I wonder if that is so it "fits" with the filmback that the nuke camera has? Setting both the focal length and filmback to the Maya/Boujou-numbers doesn't seem to make a difference acctually. That's what made me think that Nuke makes some conversion during import so the focal length matches the filmback...

Also, a good question is if I should change the translation order. Gota check what maya has as default.

Anyways, seems like this case can be closed. But if someone has more information or some answer to the, still, open questions I'm all ears. =)

[fr3drik]

The focal length seems to undergo some kind of conversion when it's imported with the chan file.

If you're talking about the value in the .chan file that comes after trans/rot xyz, it's not the focal lenght. It's the "vertical field of view", which is assumed to be an angle.

This is a note from the developers:

The current camera import/export was designed to match the data files we happened to have from Houdini. If you are talking to a different program you may be able to save a lot of headache by directly converting their data to what the camera wants. The camera does not care at all about any height value and does not use any trigonometry. The actual value of interest is the ratio of focal_length to width.

Take a look at the import_chan_file.tcl plugin, it should be possible to modify this to import other tables of data.

[sl0throp]

Your Maya and Nuke film back need to match. Maya's film back(not sure why) is in inches while nukes film back is in mm. So just take your Maya film back numbers convert them into mm. Make sure your FOV matches and as long as you have set your rotation order to xyz which you did everything will sync up fine.

s

[NEO]

Thanks Fredrik and sl0throp for helping out! The track worked out pretty nicely and everybody seemed pretty happy about it. But happiest am I for getting a chance to explore Nuke even further. I like it more for every time I open it.

But I must once again point out that what makes Nuke so powerful for large companies can be a pain for smaller companies. What I mean is that it lacks features that are so vital and features that larger companies have hired code monkeys to fix. My suggestion to the new owner of Nuke is to work tight with these larger companies and maybe pay them for their developed scripts so they can be bundled with future versions of Nuke. I know there are several issues with this, like with support and so. But they could be shiped just like the BonusTools for Maya are shiped. O well, anyways. I gona stop naging.

Just really wanted to say thank you to all you guys for helping out! It means alot! So, THANKS! =)