WorldViz User Forum focal length
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#1
12-08-2011, 06:04 AM
 dpamplona Member Join Date: Dec 2011 Posts: 7
focal length

Hi!
I would like to control the focal length of the viewpoint.
I have found the field of view command, but I cannot find something equivalent to the focal length.
Do you know how can I do that?
Best,
Daniela
#2
12-08-2011, 04:59 PM
 Jeff WorldViz Team Member Join Date: Aug 2008 Posts: 2,466
Can you describe the effect you are trying to achieve?
#3
12-12-2011, 07:01 AM
 dpamplona Member Join Date: Dec 2011 Posts: 7
effect

Sure! I will try to be as clear as possible.

In normal cameras, eyes, etc, the size of the sensor is fixed and we can control manually (or automatically) the focal length. From that, the field of view of the image, is relatively easy to estimate. (If we assume the perspective tranform, then it is just the fov = 2*arctan(sensor_array_length/(2focal_length)))

In vizard, we can control easily the fov of the viewport, I would like to adjust the viewport size (in pixels) depending on the focal length. Can you help me?
Cheers,
Daniela
#4
12-12-2011, 06:53 PM
 Jeff WorldViz Team Member Join Date: Aug 2008 Posts: 2,466
Do you want the viewport to remain rectangular?
When the viewport gets smaller are you wanting to see a black border around it?
#5
12-19-2011, 02:53 AM
 dpamplona Member Join Date: Dec 2011 Posts: 7
problem explanation

Hi!
I can have the viewpoint window rectangular or squared, (that we can control with the fovH, or fovV, or h2vRatio).

I think I was not very clear with my problem.
If the "frame size"/"sensor size" is fixed in Vizard, than the focal length is easy to estimate/set with the fov.

http://en.wikipedia.org/wiki/Angle_o..._angle_of_view

For instance, it seems that openGL uses the tipical frame size:24mm x 36mm,
http://www.opengl.org/discussion_boa...&Number=193124
is Vizard also using this values?

#6
12-20-2011, 11:02 AM
 farshizzo WorldViz Team Member Join Date: Mar 2003 Posts: 2,849
You can adjust the size of the window by using the viz.window.setSize([width,height]) command.
#7
12-23-2011, 04:18 AM
 dpamplona Member Join Date: Dec 2011 Posts: 7
Set size option

Hi!
I thought about that as well, but the setsize function comes in pixels, and the focal length in mm. If I could set the size of the window in mm, that would be enough!
Thank you!
#8
12-25-2011, 04:26 AM
 dpamplona Member Join Date: Dec 2011 Posts: 7

How can we set the window size in mm?

 Tags field of view, focal length

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