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3d object in front of ARCamera

December 20, 2014 - 7:06am #1

Hi folks,

I'm not sure where to post this, so I hope this location is ok.

This is my issue:

- in unity I create a plane in front of the camera (centered to the viewport), in the game view it fits exactly. I am using a landscape mode.

- as soon as I press play the camera seems to zoom in on the plane and the plane no longer fits the viewport.

I saw it might be related to vuforia needing to stretch the camera image or something like that, but vuforia says the video feed is 640x480, which is exactly the resolution I used to position everything.

What is causing this and how can I fix it? Right now I am using this method to recalculate the fov the ARCamera is using to reposition my objects:

        Vector3 worldPoint = QCARManager.Instance.ARCamera.ScreenToWorldPoint(new Vector3(0, 0, 10));
        Vector3 localPoint = QCARManager.Instance.ARCamera.transform.InverseTransformPoint(worldPoint);
        float halfFov = Mathf.Atan2(localPoint.y, localPoint.z);
 

It results in an fov that is different than that what the editor is showing, but it actually works.

It seems like such a basic thing: position something in front of the camera and make it fit the viewport?

I need this functionality because I want to move objects from the marker space to the camera space and back again.

Thanks in advance for better ideas!

Hans

 

 

sorv
Joined:
January 24, 2014
Posts: 12
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3d object in front of ARCamera

January 18, 2015 - 9:50am #5

Hi Alessandro,

thanks for the info! Much appreciated!

best,

Hans

sorv
Joined:
January 24, 2014
Posts: 12
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3d object in front of ARCamera

January 11, 2015 - 12:41pm #4

Vuforia sets the camera projection matrix using its own perspective and fov (the actual fov used is a fairly accurate representation of the actual device camera optics);

however, the actual FOV returned by Unity via camera.fieldOfView does not correspond to the actual Fov used by Vuforia at runtime; if you are looking for the actual FOV value used by Vuforia, you need to:

- get the unity camera projection matrix ==> see: http://docs.unity3d.com/ScriptReference/Camera-projectionMatrix.html

- derive the actual FOV (in radians) from the projection matrix, using standard projection matrix maths

 

AlessandroB
Joined:
October 9, 2012
Posts: 8591
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3d object in front of ARCamera

January 10, 2015 - 6:07am #3

Hi David,

I'm seeing on asus google nexus devices. I was assuming that even if vuforia overrides the vof, that I could update to the value vuforia is using by just reading it out through code.

best,

Hans

sorv
Joined:
January 24, 2014
Posts: 12
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3d object in front of ARCamera

December 22, 2014 - 11:41am #2

Vuforia overrides the FOV setting in the editor, so don't go by that value. Which devices are you seeing the effect on?

DavidBeard
Joined:
January 30, 2012
Posts: 2791
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