Dear Utkarsh, Thanks for the great hint! By forcing the update of view-up using cam.OrthogonalizeViewUp() on initialization as well as on changing azimuthal angle etc., I can successfully change azimuth angle instead of rolling.
Thanks again. Kazuyoshi From: Utkarsh Ayachit <[email protected]> Subject: Re: [Paraview] Is the VIEW-UP vector updated automatically? Date: Mon, 6 Oct 2014 20:49:35 -0400 > The meaning of azimuth, elevation etc. is indeed same with VTK and > ParaVIew. ParaView uses the same code for Camera as in VTK, so there's > no different there. Here's some explanation on the inner workings of > the camera: > > + The camera->ViewUp is used by vtkCamera as a "hint" for the up > direction. Thus, it is need not always be orthogonal to the view > direction (defined by camera position and camera focal point). Unless > the ViewUp is parallel to the view -direction, the vtkCamera will > automatically compute the true "viewup" internally using > vtkCamera::ViewUp as a hint. > + You can use cam.OrthogonalizeViewUp() to force the vtkCamera to > update the VIewUp based on the internally used ViewUp. > > e.g. > >>>> cam = GetActiveCamera() >>>> cam.SetPosition(0, 3, 3) >>>> Render() >>>> cam.GetViewUp() > (0.0, 1.0, 0.0) >>>> cam.OrthogonalizeViewUp() >>>> cam.GetViewUp() > (0.0, 0.7071067811865476, -0.7071067811865476) > > I am not sure I observe the same problem as you mention with Azimuth/Roll. > > Utkarsh > > On Mon, Oct 6, 2014 at 8:25 PM, Kazuyoshi Furutaka > <[email protected]> wrote: >> Could someone tell me whether the meanings of the azimuth and >> the elevation in ParaView the same as those in VTK (or "The >> Visualization Toolkit" book, 4th ed.) or not? >> >> In the book it reads: >> "Changing the \textit{azimuth} of a camera rotates its position >> around its view up vector, centered at the focal point. Think >> of this as moving the cmaera to the left or right while always >> keeping the distance to the focal point constant. Changing a >> camera's \textit{elevation} rotates its position around the cross >> product of its direction of projection and view up centered at the >> focal point. This corresponds to moving the camera up and down. >> To \textit{roll} the camera, we rotate the view up vector about >> the view plane normal. Roll is sometimes called twist." >> >> I sometimes observe that (in the Multi Slice view,) Azimuth() >> "rolls" instead of moving the camera left/right. >> >> That's why I want to understand the geometry of view-up, direction >> of projection, and so on... >> >> Kazuyoshi >> >> >> From: Kazuyoshi Furutaka <[email protected]> >> Subject: Re: [Paraview] Is the VIEW-UP vector updated automatically? >> Date: Tue, 07 Oct 2014 08:57:30 +0900 (JST) >> >>> I just want to write a Python macro to change/rotate the camera >>> position using Azimuth() and Elevation(). >>> >>> In addition to the following: >>> >>>> I'm observing a curious behavior of paraview.simple.Azimuth(); >>>> camera is NOT moving left/right. >>> >>> I sometimes get the following message >>> >>> Warning: In >>> /home/furutaka/work/ParaView/ParaView.git/VTK/Rendering/Core/vtkRenderer.cxx, >>> line 1030 >>> vtkOpenGLRenderer (0xa702510): Resetting view-up since view plane normal is >>> parallel >>> >>> and am wondering how can the view-up be parallel to the view-plane >>> normal... >>> >>> My understanding is that the view-up is (always) perpendicular to >>> the direction of projection (pointing upward of the computer display) >>> and therefore parallel to the view-plane, so the view-up should always >>> be normal to view-plane normal. >>> Isn't the view-plane normal parallel to the direction of projection? >>> Isn't the view-plane parallel to the front/back clipping planes? >> -- >> Kazuyoshi Furutaka >> furutaka _dot_ kazuyoshi _at_ jaea _dot_ go _dot_ jp >> _______________________________________________ >> Powered by www.kitware.com >> >> Visit other Kitware open-source projects at >> http://www.kitware.com/opensource/opensource.html >> >> Please keep messages on-topic and check the ParaView Wiki at: >> http://paraview.org/Wiki/ParaView >> >> Follow this link to subscribe/unsubscribe: >> http://public.kitware.com/mailman/listinfo/paraview _______________________________________________ Powered by www.kitware.com Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html Please keep messages on-topic and check the ParaView Wiki at: http://paraview.org/Wiki/ParaView Follow this link to subscribe/unsubscribe: http://public.kitware.com/mailman/listinfo/paraview
