Why did changing camera focal point position NOT result in zooming in/out?

> Hello:
>
> I have tried to changed position of the camera focal point to zoom in/out
> the point cloud. I fixed the view up vector, the camera position and the
> direction
> betweeen the camera position and the camera focal point. I only changed the
> distance between the camera focal point and the camera position. My
> observations have been that no matter how I change this distance value, the
> view I see on the screen do not change!
>
> Any suggestion on this is appreciated.
>
> Thanks.
>
> Ziyou
>
>
>
> --
> View this message in context: http://www.pcl-users.org/Why-did-changing-camera-focal-point-position-NOT-result-in-zooming-in-out-tp4020991.html
> Sent from the Point Cloud Library (PCL) Users mailing list archive at Nabble.com.
> _______________________________________________
> [hidden email] / http://pointclouds.org
> http://pointclouds.org/mailman/listinfo/pcl-users
>

> Radu:
>
> Thanks for your reply.
>
> I tried your suggestion, but it did not work.
>
> I looked into this problem a bit further. It turns out just like the camera
> model OpenGL uses, where the exact value of the camera focal point position
> does not matter when it comes to zooming. Only the direction between the
> focal point and the camera center position plays a role in rendering, not
> the distance between them. To perform zooming, either the camera center
> position needs to move ( as in function Dolly() in VTK), or the camera
> ViewAngle needs to change by changing .
> camera_.fovy.
>
> This exposes a bug in file "../visualization/src/pcl_visualizer.cpp" with
> the following two functions where camera_.fovy is not initialized or
> updated.
>
> pcl::visualization::PCLVisualizer::initCameraParameters ()
>
> pcl::visualization::PCLVisualizer::updateCamera ()
>
> This also explains why the 5th parameter in "-cam p1/p2/p3/p4/p5/p6/p7" for
> pcd_viewer is ignored as it is always set to be the default value of 0.5253
> (radians, i.e. 30 degrees).
>
> Thanks.
>
> Ziyou
>
>
>
>
> --
> View this message in context: http://www.pcl-users.org/Why-did-changing-camera-focal-point-position-NOT-result-in-zooming-in-out-tp4020991p4021087.html
> Sent from the Point Cloud Library (PCL) Users mailing list archive at Nabble.com.
> _______________________________________________
> [hidden email] / http://pointclouds.org
> http://pointclouds.org/mailman/listinfo/pcl-users
>

> Radu:
>
> My solution is:
>
> (1) added statement:
>
> camera_.fovy = 0.5235987667;
>
> to the last line in function
> pcl::visualization::PCLVisualizer::initCameraParameters ()
>
> (2) add statement:
>
> renderer->GetActiveCamera ()->SetViewAngle(camera_.fovy * 180 / M_PI);
>
> after renderer->GetActiveCamera ()->SetClippingRange (camera_.clip);
>
> in function pcl::visualization::PCLVisualizer::updateCamera ()
>
>
> FYI, both of these functions are in file pcl_visualizer.cpp.
>
> Thanks.
>
> Ziyou
>
>
>
> --
> View this message in context: http://www.pcl-users.org/Why-did-changing-camera-focal-point-position-NOT-result-in-zooming-in-out-tp4020991p4022368.html
> Sent from the Point Cloud Library (PCL) Users mailing list archive at Nabble.com.
> _______________________________________________
> [hidden email] / http://pointclouds.org
> http://pointclouds.org/mailman/listinfo/pcl-users
>