Hello 
I'm looking to use the jetfitting algorithm to compute the principal curvature and directions at various nonvertex points of a (triangular mesh) i.e. my points of interest lie on the faces of a mesh, and by definition, do not coincide with its vertexes. My question however concerns the method used by the implementation of the jetfitting algorithm in this case. I would like to confirm if the jetfitting algorithm uses an (a) interpolation or (b) approximation approach to compute the differential properties at such novertex points  the former would be preferred. I'm aware that this issue was discussed on page 12 of "Jet fitting 3: A Generic C++ Package for Estimating the Differential Properties on Sampled Surfaces via Polynomial Fitting", but I found the reading a bit confusing probably because I'm only just learning the algorithm. Thanks,  Olumide  You are currently subscribed to cgaldiscuss. To unsubscribe or access the archives, go to https://listssop.inria.fr/wws/info/cgaldiscuss 
Hello,
i summarize here the discussion we had by phone: you can use interpolation with the jet fitting if you give exactly the nb of points that correspond to the nb of constraints. Then, by default, the differential quantities returned are those computed at the projection of the first point you have given on the fitted polynomial surface. If you want to compute the quantities for another point p, and you dont want this point to be taken into account to do the fitting (eitherwise just give this point first and you are done); you can just project this point on the fitted surface (that is given by the monge form in the monge coordinate system) and compute the diff quantities by classical diff geo formula. I may consider adding this functionality in the future ... best Marc On 28 , May , 2008, at 06:42 , Olumide wrote: > Hello  > > I'm looking to use the jetfitting algorithm to compute the > principal curvature and directions at various nonvertex points of > a (triangular mesh) i.e. my points of interest lie on the faces of > a mesh, and by definition, do not coincide with its vertexes. > > My question however concerns the method used by the implementation > of the jetfitting algorithm in this case. I would like to confirm > if the jetfitting algorithm uses an (a) interpolation or (b) > approximation approach to compute the differential properties at > such novertex points  the former would be preferred. > > I'm aware that this issue was discussed on page 12 of "Jet fitting > 3: A Generic C++ Package for Estimating the Differential Properties > on Sampled Surfaces via Polynomial Fitting", but I found the > reading a bit confusing probably because I'm only just learning the > algorithm. > > Thanks, > >  Olumide > > >  > You are currently subscribed to cgaldiscuss. > To unsubscribe or access the archives, go to > https://listssop.inria.fr/wws/info/cgaldiscuss  You are currently subscribed to cgaldiscuss. To unsubscribe or access the archives, go to https://listssop.inria.fr/wws/info/cgaldiscuss 
hi,
I want to get the (axis aligned) bounding box of a given polyhedron_3. I don't know if there is an existing funtion to do this. thanks for any hints. B/Rgds Max  You are currently subscribed to cgaldiscuss. To unsubscribe or access the archives, go to https://listssop.inria.fr/wws/info/cgaldiscuss 
Max wrote:
> hi, > > I want to get the (axis aligned) bounding box of a given polyhedron_3. > I don't know if there is an existing funtion to do this. > > thanks for any hints. > > B/Rgds > Max > Hi Max, There is no bbox() member function that caches and updates the bbox whenever you change the Polyhedron_3. The most compact piece of code for computing the bbox in linear time looks like this #include <CGAL/bounding_box.h> Polyhedron_3 poly; CGAL Bbox_3 bb = CGAL::bounding_box(poly.points_begin(), points_end()).bbox(); andreas  You are currently subscribed to cgaldiscuss. To unsubscribe or access the archives, go to https://listssop.inria.fr/wws/info/cgaldiscuss 
>Hi Max,
> >There is no bbox() member function that caches and updates >the bbox whenever you change the Polyhedron_3. > >The most compact piece of code for computing the bbox in linear time >looks like this > > >#include <CGAL/bounding_box.h> > >Polyhedron_3 poly; > > >CGAL Bbox_3 bb = CGAL::bounding_box(poly.points_begin(), points_end()).bbox(); > > >andreas Hello andreas, Thank you very much for your quick and detailed reply. That's enough for my current demand. B/Rgds Max  You are currently subscribed to cgaldiscuss. To unsubscribe or access the archives, go to https://listssop.inria.fr/wws/info/cgaldiscuss 
>Hello andreas,
> >Thank you very much for your quick and detailed reply. >That's enough for my current demand. > >B/Rgds >Max Just one more question  suppose I have a bunch of bbox_3, what is the convenient way to get the 'union' of them. Thanks and B/Rgds. Max  You are currently subscribed to cgaldiscuss. To unsubscribe or access the archives, go to https://listssop.inria.fr/wws/info/cgaldiscuss 
Max wrote:
> > Just one more question  suppose I have a bunch of bbox_3, > what is the convenient way to get the 'union' of them. There doesn't seem to be a function that does this. But, using the values of x/y/zmin(), x/y/zmax(), you can easily create a function that does this for your bbox_3 list. Regards, ~ash  You are currently subscribed to cgaldiscuss. To unsubscribe or access the archives, go to https://listssop.inria.fr/wws/info/cgaldiscuss 
Administrator

Ashwin Nanjappa a écrit :
> Max wrote: >> Just one more question  suppose I have a bunch of bbox_3, >> what is the convenient way to get the 'union' of them. > > There doesn't seem to be a function that does this. But, using the values > of x/y/zmin(), x/y/zmax(), you can easily create a function that does > this for your bbox_3 list. Maybe std::accumulate ?  Sylvain Pion INRIA SophiaAntipolis Geometrica ProjectTeam CGAL, http://cgal.org/ smime.p7s (5K) Download Attachment 
Sylvain Pion wrote:
> Ashwin Nanjappa a écrit : >> Max wrote: >>> Just one more question  suppose I have a bunch of bbox_3, >>> what is the convenient way to get the 'union' of them. >> There doesn't seem to be a function that does this. But, using the values >> of x/y/zmin(), x/y/zmax(), you can easily create a function that does >> this for your bbox_3 list. > > Maybe std::accumulate ? That would be an elegant way to implement it! Thanks for the suggestion, I wasn't aware of this STL function. Regards, ~ash  You are currently subscribed to cgaldiscuss. To unsubscribe or access the archives, go to https://listssop.inria.fr/wws/info/cgaldiscuss 
Free forum by Nabble  Edit this page 