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kubabuk

Free Vs. Target Camera

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I am having a weird problem which definitely lays in a small capacity of my brain. I can't understand the difference between target and free camera, to be more specific I am not sure if those two types of cameras uses different methods of calculating position and direction in space?!?

Some time ago I created a tool to bring a camera from max to houdini. Everything worked fine in animated and still shots up to the moment where I've found out that renderings from free camera with the frame rate of 25fps completely don't match with those ones rendered in houdini (Everything was off except the first frame).

It's interesting because the same animation with the frame rate of 30fps worked perfectly. The same thing was with the target camera, I didn't have any problem with it at any frame rate...

I am slightly confused at the moment, and not sure if that is a bug or rather my error. So if anybody have any clue which direction should I follow I will really appreciate. Right now I suspect that this might be a problem with the different order houdini and max calculates translations and rotations, but that is a weak argument to me, since free camera doesn't work only at 25fps. What do you think about that?

Thanks

kuba

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thats really wierd, cause we have a system that can take cameras out of what ever tool and use them in houdini and back out with out any issues, and we use normal cameras without targets.

what makes me think that its a human error is that u say that the first frame is the same,

Im presuming that u are bringing in the animation using chops,

it may be the sample rate under chops and ur hip play back rate arent the same,

have u checked how the values differ in each package?

what file format are u using to transfer the animation curves across?

I also know that max uses Z up scene space, that was an issue for us.

:blink:

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Hi,

Brian made a very good point about using CHOPs and that is the Sample Rate. When you read in the data through a File CHOP, make sure to Override or Resample the Rate chosen by the user or you can query the fps of the hip file & use that.

Cheers!

steven

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Hi,

Brian made a very good point about using CHOPs and that is the Sample Rate. When you read in the data through a File CHOP, make sure to Override or Resample the Rate chosen by the user or you can query the fps of the hip file & use that.

Cheers!

steven

thanks for such a fast feedback :)

I am exporting data from max straight to *.chan file, then load it into chops. I have my rate option set to Override and sample rate the same as the frame rate of my file (see attachment), which is of course equal to the frame rate of the max file...

I've made couple of times a mistake and forgot to set proper frame rate in my hip file, but in that case at least at each keyframe cameras where aligned :( right now they are completely off.

thanks

kuba

post-823-1179411712_thumb.jpg

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I should say " YES, YES, YES!!" :)

YES, that was the human error. :rolleyes:

The in fact problem wasn't in the CHOPs, but on the camera node itself. The transform order for rotations has to be RX RZ RY instead of default RX RY RZ.

(still wondering why that didn't give me an error on 30fps animation...?)

I will post an update of the otl after I'll make sure that really works ;)

cheers

kuba

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