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FOV value isn't accurate from what I can tell

Posted: Sun Apr 25, 2010 4:43 pm
by cgbeige
I'm trying to do a comp match for something and trying to match the focal length. Octane shows an fov of 45° but Maya's focal length to match it is 25°. Is there some sort of camera back setting I need to change to get this to work at 45° or is Octane's value inaccurate?

Re: FOV value isn't accurate from what I can tell

Posted: Sun Apr 25, 2010 5:39 pm
by radiance
octane uses field of view angle in degrees,
maybe maya uses a different lens unit ?

Radiance

Re: FOV value isn't accurate from what I can tell

Posted: Sun Apr 25, 2010 5:59 pm
by ahooo
FOV can be measured horisontally, vertically or diagonal... Don't know which one Maya or Octane uses, but my guess is that they're measuring different angles :-)

In 3ds max, the camera object has separate inputs for these three FOVs, maybe Maya has too?

Re: FOV value isn't accurate from what I can tell

Posted: Sun Apr 25, 2010 8:30 pm
by face
FOV and focal length are two differnt things.
Focal length is in Softimage a length in mm. The focus point where the camera see sharp. This should be used for e.g. DOF.
FOV are the angle who the scene is seen.

Re: FOV value isn't accurate from what I can tell

Posted: Sun Apr 25, 2010 10:07 pm
by face
Another question i have, how can i use the focaldepth option?
I mean, give it a similar parameter in a 3d-package?

Re: FOV value isn't accurate from what I can tell

Posted: Mon Apr 26, 2010 8:29 am
by radiance
face wrote:Another question i have, how can i use the focaldepth option?
I mean, give it a similar parameter in a 3d-package?
it's not yet hooked up,
on my list for 2.2

Radiance

Re: FOV value isn't accurate from what I can tell

Posted: Mon Apr 26, 2010 5:04 pm
by cgbeige
ya, sorry I said FOV when I meant angle. I was using the angle value and having to do 25° in Maya to get it to match the 45° value in Octane, even with the crop dimensions set the same.

This would be a lot easier to do with an FBX camera import/export - at least that way, I wouldn't have to reposition the camera, I could just tweak the angle value. As it is, it's a very finicky thing, trying to match them.

Re: FOV value isn't accurate from what I can tell

Posted: Mon Apr 26, 2010 6:40 pm
by radiance
cgbeige wrote:ya, sorry I said FOV when I meant angle. I was using the angle value and having to do 25° in Maya to get it to match the 45° value in Octane, even with the crop dimensions set the same.

This would be a lot easier to do with an FBX camera import/export - at least that way, I wouldn't have to reposition the camera, I could just tweak the angle value. As it is, it's a very finicky thing, trying to match them.
we fixed a bug in RC1 that's now fixed in the new final i just posted,
that resolved the other issue, eg the camera being not correct horizontally.

Radiance

Re: FOV value isn't accurate from what I can tell

Posted: Mon Apr 26, 2010 9:01 pm
by cgbeige
ok - it looks like it's sort of fixed. Default camera and angle is matched:

http://grab.by/41gT

But when I try and change the angle to 80 and do some simple translates, the offsets are completely different:

http://grab.by/41hl

Re: FOV value isn't accurate from what I can tell

Posted: Mon Apr 26, 2010 9:05 pm
by cgbeige
ok - it looks like the problem is that the "pos" Y and Z values rotate the camera, not translate it.