Hi Robert, If I extended the RayTracedTechnique and override the default VERTEX and FRAGMENT glsl codes to replace my own glsl code, which will measure distance along the ray. Are you talking about this case to overcome the aliasing artifact ?
Regards, Clement ________________________________________ From: osg-users-boun...@lists.openscenegraph.org [osg-users-boun...@lists.openscenegraph.org] On Behalf Of Robert Osfield [robert.osfi...@gmail.com] Sent: Tuesday, 26 June 2012 4:41 AM To: OpenSceneGraph Users Subject: Re: [osg-users] Antialiasing in Volume rendering Hi Clement, The datasets you are working of will always challenge a ray traced sampler as there is sudden cutoff to a flat face so that any small change in adjacent pixels can result in a enough of different sampling as to result in a visible step. Increasing sample density will usually reduce the step and make it less obvious but unless you go sub pixel it will likely remain visible. Another route one could go is to use a different shader that samples at texel centers rather than just a measured distance along the ray as is done with the present shaders. Also I think you'll find that this aliasing artefacts will be far less noticeable on more normal volume datasets so it may be worth just making a judgment call about whether these datasets are meaningful and worthy of trying to optimize for. Robert. On 25 June 2012 17:55, <clement....@csiro.au> wrote: > Hi Robert, > > Thanks for your advice. It looks better if I increased sample density. > When I tried on another case, see the attachment. If colour is filled in > center section only and increased the sample density, the aliasing became > much worse. If I decreased the sample density, it looks better. Dp you know > when should I adjust the sample density to reduce aliasing? > > > Regards, > Clement > ________________________________________ > From: osg-users-boun...@lists.openscenegraph.org > [osg-users-boun...@lists.openscenegraph.org] On Behalf Of Robert Osfield > [robert.osfi...@gmail.com] > Sent: Tuesday, 26 June 2012 1:34 AM > To: OpenSceneGraph Users > Subject: Re: [osg-users] Antialiasing in Volume rendering > > Hi Clement, > > On 25 June 2012 13:29, <clement....@csiro.au> wrote: >> Sorry, I forget to attach the images. >> >> Top image: there is no aliasing. >> Bottom image: aliasing appears on the side that has not been filled colour. > > As I suspected the aliasing is down to under sampling of the ray, so > up the sample ratio. > > Robert. > _______________________________________________ > osg-users mailing list > osg-users@lists.openscenegraph.org > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org > > _______________________________________________ > osg-users mailing list > osg-users@lists.openscenegraph.org > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org > _______________________________________________ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org _______________________________________________ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
