From biedl at math.uwaterloo.ca Mon Apr 2 12:08:58 2001 From: biedl at math.uwaterloo.ca (Therese Biedl) Date: Mon Jan 9 13:41:01 2006 Subject: CCCG'01: Second Call for Papers Message-ID: -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Second Call for Papers 13th Canadian Conference on Computational Geometry August 13-15, 2001 University of Waterloo http://compgeo.math.uwaterloo.ca/~cccg01 -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- [Due to unanticipated shorter printing schedule, we are able to shift the deadline by two weeks. The new deadline for paper submission is April 30, 2001.] Objectives ========== The Canadian Conference on Computational Geometry (CCCG) focuses on the mathematics of discrete geometry from a computational point of view. Abstracting and studying the geometry problems that underly important applications of computing (such as geographic information systems, computer-aided design, simulation, robotics, solid modeling, databases, and graphics) leads not only to new mathematical results, but also to improvements in these applications. Despite its international following, CCCG maintains the informality of a smaller workshop and attracts a large number of students. Call for Papers =============== Authors are invited to submit papers describing research of theoretical and practical significance to computational geometry. Electronic submissions, in standard PostScript and not exceeding 4 pages length, should be made using the SIGACT Electronic Submissions Server. Details can be found on the conference web page. A special issue of Computational Geometry: Theory and Applications will be devoted to invited papers from the conference. Program Committee ================= Therese Biedl (Univ. of Waterloo) Timothy Chan (Univ. of Waterloo) Erik Demaine (Univ. of Waterloo) David Kirkpatrick (Univ. of British Columbia) Anna Lubiw (Univ. of Waterloo) Joseph O'Rourke (Smith College) Godfried Toussaint (McGill University) Organizing Committee ==================== Therese Biedl (Univ. of Waterloo) Erik Demaine (Univ. of Waterloo) Martin Demaine (Univ. of Waterloo) Anna Lubiw (Univ. of Waterloo) Important dates =============== Submission of papers: April 30, 2001 Notification of acceptance: May 29, 2001 Submission of final paper: June 29, 2001 Conference: August 13-15, 2001 Contact Information =================== Therese Biedl Dept. of Computer Science University of Waterloo Waterloo, ON N2L 3G1 Phone: (519) 888-4567x4721 Fax: (519) 885-1208 Email: biedl@uwaterloo.ca Sponsors ======== CCCG '01 is supported by CRM, The Fields Institute, PIMS and the University of Waterloo. ------------- The compgeom mailing lists: see http://netlib.bell-labs.com/netlib/compgeom/readme.html or send mail to compgeom-request@research.bell-labs.com with the line: send readme Now archived at http://www.uiuc.edu/~sariel/CG/compgeom/maillist.html. From John.Dickinson at nrc.ca Mon Apr 9 10:26:50 2001 From: John.Dickinson at nrc.ca (Dickinson, John) Date: Mon Jan 9 13:41:01 2006 Subject: Silhouette of a facetted polyhedra Message-ID: <35C5DD9F60FED21192B00004ACA6E6C7FFFBF8@nrclonex1.imti.nrc.ca> I want to get the shadow or projection of a 3D facetted polyhedra on a plane. In other words I want to project all the triangles that describe the surface of the polyhedra onto a plane and union them so that I have a polygon possibly with inclusions or holes (e.g. project a donut onto a plane perpendicular to the axis of its hole). Can anyone point me to some code or papers that would give decent algorithms for doing this (specifically the union of all the facets into a polygon)? The goal of this is to determine the centroid and area of the resultant projection. Is there a way to do this without building the projected polygon first? John -- -((Insert standard disclaimer here))-|--- Washington Irving (1783-1859) ---- John Kenneth Dickinson | "A sharp tongue is the only Research Council Officer IMTI-NRC | edge tool that grows keener email: john.dickinson@nrc.ca | with constant use." http://publish.uwo.ca/~jkdickin/ | ------------- The compgeom mailing lists: see http://netlib.bell-labs.com/netlib/compgeom/readme.html or send mail to compgeom-request@research.bell-labs.com with the line: send readme Now archived at http://www.uiuc.edu/~sariel/CG/compgeom/maillist.html. From j.winkler at dcs.shef.ac.uk Mon Apr 9 15:43:08 2001 From: j.winkler at dcs.shef.ac.uk (Joab Winkler) Date: Mon Jan 9 13:41:01 2006 Subject: Workshop, Sheffield July 2001 Message-ID: <200104091343.OAA12774@padley.dcs.shef.ac.uk> ***** Apologies for multiple receipts of this e-mail ***** Dear Colleague, Registration is now open for the workshop ** Uncertainty in Geometric Computations, 5-6 July 2001, Sheffield ** The representation and management of uncertainty is an important issue in several different disciplines, such as numerical problems in computer graphics that occur when calculating the intersection curve of two surfaces, high performance pattern classification in a feature space, and the study of families of probability distributions in information geometry. The aim of this two-day workshop is to explore the underlying geometric theme that is common to these diverse disciplines. The workshop will consist of a number of invited contributions of a tutorial nature covering the different topics, contributed papers from participants and discussion sessions that explore the connections. Contributions will be published by Kluwer in an edited volume. The workshop is sponsored by the Engineering and Physical Sciences Research Council (EPSRC) and London Mathematical Society (LMS). The total number of participants is limited to 70. The workshop is sponsored by the London Mathematical Society and Engineering and Physical Sciences Research Council. For further information see: http://www.shef.ac.uk/~geom2001/ In order to register, please use the registration form on this web page. Best regards Joab Winkler ------------------------------------------ Dr Joab R Winkler The University of Sheffield Department of Computer Science Regent Court 211 Portobello Street Sheffield S1 4DP United Kingdom Tel : +44 114 222 1834 Fax : +44 114 222 1810 E-mail : j.winkler@dcs.shef.ac.uk ------------- The compgeom mailing lists: see http://netlib.bell-labs.com/netlib/compgeom/readme.html or send mail to compgeom-request@research.bell-labs.com with the line: send readme Now archived at http://www.uiuc.edu/~sariel/CG/compgeom/maillist.html. From John.Dickinson at nrc.ca Wed Apr 11 10:17:21 2001 From: John.Dickinson at nrc.ca (Dickinson, John) Date: Mon Jan 9 13:41:01 2006 Subject: Silhouette of a facetted polyhedra Message-ID: <35C5DD9F60FED21192B00004ACA6E6C7FFFC0A@nrclonex1.imti.nrc.ca> Unfortunately, hardware solutions aren't practical in this case. I do, however, have the luxury of doing the projection calculations off-line. John -----Original Message----- From: Hans Pedersen [mailto:Hans@paraform.com] Sent: Tuesday, April 10, 2001 5:47 PM To: 'Dickinson, John' Subject: RE: Silhouette of a facetted polyhedra Hi John, You can use graphics hardware to reduce this to a 2d image processing operation that will give you an approximation to centroid/area: Render all the polygons on the plane that you want and compute centroid/ area from the resulting binary image. You can get any accuracy you want by increasing the resolution of the image. Just an idea - good luck! Hans --- Hans K. Pedersen Sr. Software Engineer Paraform Inc Santa Clara, California, USA -----Original Message----- From: Dickinson, John [ mailto:John.Dickinson@nrc.ca ] Sent: Monday, April 09, 2001 6:27 AM To: 'compgeom-discuss@research.bell-labs.com' Subject: Silhouette of a facetted polyhedra I want to get the shadow or projection of a 3D facetted polyhedra on a plane. In other words I want to project all the triangles that describe the surface of the polyhedra onto a plane and union them so that I have a polygon possibly with inclusions or holes (e.g. project a donut onto a plane perpendicular to the axis of its hole). Can anyone point me to some code or papers that would give decent algorithms for doing this (specifically the union of all the facets into a polygon)? The goal of this is to determine the centroid and area of the resultant projection. Is there a way to do this without building the projected polygon first? John -- -((Insert standard disclaimer here))-|--- Washington Irving (1783-1859) ---- John Kenneth Dickinson | "A sharp tongue is the only Research Council Officer IMTI-NRC | edge tool that grows keener email: john.dickinson@nrc.ca | with constant use." http://publish.uwo.ca/~jkdickin/ | ------------- The compgeom mailing lists: see http://netlib.bell-labs.com/netlib/compgeom/readme.html or send mail to compgeom-request@research.bell-labs.com with the line: send readme Now archived at http://www.uiuc.edu/~sariel/CG/compgeom/maillist.html . -------------- next part -------------- An HTML attachment was scrubbed... URL: http://compgeom.poly.edu/pipermail/compgeom-announce/attachments/20010411/c739a470/attachment.htm From John.Dickinson at nrc.ca Wed Apr 11 10:28:30 2001 From: John.Dickinson at nrc.ca (Dickinson, John) Date: Mon Jan 9 13:41:01 2006 Subject: Silhouette of a facetted polyhedra Message-ID: <35C5DD9F60FED21192B00004ACA6E6C7FFFC0B@nrclonex1.imti.nrc.ca> Thanks for the pointer. I checked out your online abstracts an they look impressive but not really along the line or simplicity of what I am looking for. I can reduce my task to the more simple problem of unioning many triangulare planar facets together and then working with the resulting polygon. Of course, calculating the union of an unordered list of triangle facets on a plane can be very expensive if not done correctly. John -----Original Message----- From: Steven Spitz [mailto:StevenS@proficiency.com] Sent: Wednesday, April 11, 2001 4:07 AM To: 'Dickinson, John' Subject: RE: Silhouette of a facetted polyhedra John, It sounds like you are interested in related problems from computer graphics: shading, visibility, and accessibility. I personally did some work in accessibility, but used discrete techniques. You can find papers at: http://www-pal.usc.edu/html/publications.html or http://www-pal.usc.edu/~spitz Steven > -----Original Message----- > From: Dickinson, John [mailto:John.Dickinson@nrc.ca] > Sent: Monday, April 09, 2001 3:27 PM > To: 'compgeom-discuss@research.bell-labs.com' > Subject: Silhouette of a facetted polyhedra > > > I want to get the shadow or projection of a 3D facetted polyhedra on a > plane. In other words I want to project all the triangles > that describe the > surface of the polyhedra onto a plane and union them so that I have a > polygon possibly with inclusions or holes (e.g. project a > donut onto a plane > perpendicular to the axis of its hole). > > Can anyone point me to some code or papers that would give > decent algorithms > for doing this (specifically the union of all the facets into > a polygon)? > > The goal of this is to determine the centroid and area of the > resultant > projection. Is there a way to do this without building the projected > polygon first? > > John > > -- > -((Insert standard disclaimer here))-|--- Washington Irving > (1783-1859) ---- > John Kenneth Dickinson | "A sharp tongue is the only > Research Council Officer IMTI-NRC | edge tool that grows keener > email: john.dickinson@nrc.ca | with constant use." > http://publish.uwo.ca/~jkdickin/ | > > > > ------------- > The compgeom mailing lists: see > http://netlib.bell-labs.com/netlib/compgeom/readme.html > or send mail to compgeom-request@research.bell-labs.com with the line: > send readme > Now archived at http://www.uiuc.edu/~sariel/CG/compgeom/maillist.html. > ------------- The compgeom mailing lists: see http://netlib.bell-labs.com/netlib/compgeom/readme.html or send mail to compgeom-request@research.bell-labs.com with the line: send readme Now archived at http://www.uiuc.edu/~sariel/CG/compgeom/maillist.html. From John.Dickinson at nrc.ca Wed Apr 11 15:07:37 2001 From: John.Dickinson at nrc.ca (Dickinson, John) Date: Mon Jan 9 13:41:01 2006 Subject: Silhouette of a facetted polyhedra Message-ID: <35C5DD9F60FED21192B00004ACA6E6C7FFFC0F@nrclonex1.imti.nrc.ca> Good suggestion, applicable to my situation with no edge, no vertex sharing information (which I should have mentioned at the outset). Thanks, I'll look into it further. John -----Original Message----- From: Guenter Rote [mailto:rote@inf.fu-berlin.de] Sent: Wednesday, April 11, 2001 11:40 AM To: Dickinson, John Subject: Re: Silhouette of a facetted polyhedra "Dickinson, John" wrote: > > I want to get the shadow or projection of a 3D facetted polyhedra on a > plane. In other words I want to project all the triangles that describe the > surface of the polyhedra onto a plane and union them so that I have a > polygon possibly with inclusions or holes (e.g. project a donut onto a plane > perpendicular to the axis of its hole). > > Can anyone point me to some code or papers that would give decent algorithms > for doing this (specifically the union of all the facets into a polygon)? > > The goal of this is to determine the centroid and area of the resultant > projection. Is there a way to do this without building the projected > polygon first? The simplest thing to suggest is a planesweep of the projection by a vertical plane with increasing x-coordinate, maintaining the intersection intervals with each triangle. This works for an unrelated collection of triangles. You can accumulate the area and momentum that are needed for the centroid as you go. There are more advanced methods for computing unions of triangles, but they are probably not good for practice. Possible improvements may depend on the data that you have. Is it a topologically complicated polyhedron with relatively few faces, such as a tree or a gutter? Or even with topological inconsistencies/ self intersections due to data errors? Or is it a relatively smooth surface with thousands of triangles, like a donut? In that case it might pay off to concentrate on those edges that have a supporting light ray which does not (locally) penetrate the surface, the "contour" edges. -- G"unter Rote (Germany=49)30-838-75150 (office) Freie Universit"at Berlin -75103 (secretary) Institut f"ur Informatik FAX (49)30-838-75109 Takustrase 9 (49)30-84108844 (home) D-14195 Berlin, GERMANY electronic mail: rote@inf.fu-berlin.de ------------- The compgeom mailing lists: see http://netlib.bell-labs.com/netlib/compgeom/readme.html or send mail to compgeom-request@research.bell-labs.com with the line: send readme Now archived at http://www.uiuc.edu/~sariel/CG/compgeom/maillist.html. From John.Dickinson at nrc.ca Wed Apr 11 15:09:03 2001 From: John.Dickinson at nrc.ca (Dickinson, John) Date: Mon Jan 9 13:41:01 2006 Subject: Silhouette of a facetted polyhedra Message-ID: <35C5DD9F60FED21192B00004ACA6E6C7FFFC10@nrclonex1.imti.nrc.ca> I hadn't thought of this but unfortunately I don't have shared edge/vertex information available. Good point about nonconvex polyhedra having holes in shadows even if they don't have them in 3D. John -----Original Message----- From: Tom Shermer [mailto:shermer@cs.sfu.ca] Sent: Tuesday, April 10, 2001 6:22 PM To: John.Dickinson@nrc.ca Cc: shermer@cs.sfu.ca Subject: Re: Silhouette of a facetted polyhedra Hi John, the edges that are on the silhouette have a normal whose dot product with the normal of the projection plane is zero. (Depending on your definition of silhouette, the silhouettes are either exactly those with a normal with zero dot product, or a subset of them.) The easiest way I know of to test this is to take all face normals and compute their dot product with the plane normal. Then, any edge having faces with differently-signed dot products is a "silhouette" edge. If one keeps this information directly in the edge data structure, we can consider this as a coloring of the edges of the polyhedron where, say, red represents "silhouette" and blue represents "non-silhouette". Then by examining a separate list of silhouette edges, one can find connected components in the red graph and use these to form polygons. Decisions to throw out some chains can be made locally at high-degree vertices. If the polyhedron is convex, rather than testing all pairs, find an extreme vertex in some direction contained in the projection plane. This vertex will be in the silhouette, so check the edges around it to find one that is silhouette. Cross this edge and repeat at the next vertex, until you return to the start. If the polyhedron is nonconvex, then life is trickier. First, one must decide if holes are allowed in the silhouette. A silhouette can have holes even if the polyhedron doesn't. If holes are not allowed, then one can just take the union of all of the polygons that corresponding to "positive" (non-hole) silhouettes. ["Negative" (hole) silhouettes locally do not contain the object, as in the silhouette in the center of a torus.] If holes are allowed in the silhouette, I'm not quite sure how to proceed. For centroid, one only needs to identify the silhouette vertices. To compute area, take any point p on the projection plane. For each silhouette edge (again, what these are differ depending on your definition of silhouette) and orient it so that the polyhedron appears on the left as one walks from tail to the head (as viewed from above the polyhedron, where the projection plane is below). Then, compute the signed area (positive if the edge is oriented counterclockwise around p, negative otherwise) of the triangle formed by p and the projection of this edge. The sum of these, over all such triangles, is the area of the silhouette. (no construction of polygon required.) Tom shermer@cs.sfu.ca > From: "Dickinson, John" > To: "'compgeom-discuss@research.bell-labs.com'" > Subject: Silhouette of a facetted polyhedra > Date: Mon, 9 Apr 2001 09:26:50 -0400 > MIME-Version: 1.0 > > I want to get the shadow or projection of a 3D facetted polyhedra on a > plane. In other words I want to project all the triangles that describe the > surface of the polyhedra onto a plane and union them so that I have a > polygon possibly with inclusions or holes (e.g. project a donut onto a plane > perpendicular to the axis of its hole). > > Can anyone point me to some code or papers that would give decent algorithms > for doing this (specifically the union of all the facets into a polygon)? > > The goal of this is to determine the centroid and area of the resultant > projection. Is there a way to do this without building the projected > polygon first? > > John > > -- > -((Insert standard disclaimer here))-|--- Washington Irving (1783-1859) ---- > John Kenneth Dickinson | "A sharp tongue is the only > Research Council Officer IMTI-NRC | edge tool that grows keener > email: john.dickinson@nrc.ca | with constant use." > http://publish.uwo.ca/~jkdickin/ | > > > > ------------- > The compgeom mailing lists: see > http://netlib.bell-labs.com/netlib/compgeom/readme.html > or send mail to compgeom-request@research.bell-labs.com with the line: > send readme > Now archived at http://www.uiuc.edu/~sariel/CG/compgeom/maillist.html. ------------- The compgeom mailing lists: see http://netlib.bell-labs.com/netlib/compgeom/readme.html or send mail to compgeom-request@research.bell-labs.com with the line: send readme Now archived at http://www.uiuc.edu/~sariel/CG/compgeom/maillist.html. From John.Dickinson at nrc.ca Wed Apr 11 15:05:55 2001 From: John.Dickinson at nrc.ca (Dickinson, John) Date: Mon Jan 9 13:41:01 2006 Subject: Silhouette of a facetted polyhedra Message-ID: <35C5DD9F60FED21192B00004ACA6E6C7FFFC0E@nrclonex1.imti.nrc.ca> More unfortunately for me is that I don't have neighbourhood information for the model and in fact never did. I am working with a non-convex polyhedra, described by a list of triangles described by their vertices. No shared edge or vertex information exists, the polyhedra could potentially have holes/missing facets, as well as assume shapes like donuts with holes through them. Initial attempts to address this problem can be off-line (non-real time) though. Kind of a sticky problem. So far the best suggestion for my particular set of circumstances came from Guenter Rote with "The simplest thing to suggest is a planesweep of the projection by a vertical plane with increasing x-coordinate, maintaining the intersection intervals with each triangle. This works for an unrelated collection of triangles. You can accumulate the area and momentum that are needed for the centroid as you go. There are more advanced methods for computing unions of triangles, but they are probably not good for practice." Still non-trivial to implement but not too costly for pre-processing. John -----Original Message----- From: Lutz Kettner [mailto:kettner@inf.ethz.ch] Sent: Wednesday, April 11, 2001 1:44 PM To: John.Dickinson@nrc.ca Subject: Re: Silhouette of a facetted polyhedra Hi John, Do you still have neighborhood information for the facets? An approach using contour edges might speed up things. I implemented a still simple sweep line algorithm for my thesis to compute the silhouette of polyhedral surfaces (my name for your problem ;-). If you are interested, you can check out my thesis Lutz Kettner. Software Design in Computational Geometry and Contour-Edge Based Polyhedron Visualization. PhD Thesis, ETH Z?rich, Institute of Theoretical Computer Science, 148 pages, September 1999. from my web page http://www.cs.unc.edu/~kettner/pub/ Unfortunately for you, no sources released. Best regards, Lutz ------------- The compgeom mailing lists: see http://netlib.bell-labs.com/netlib/compgeom/readme.html or send mail to compgeom-request@research.bell-labs.com with the line: send readme Now archived at http://www.uiuc.edu/~sariel/CG/compgeom/maillist.html. From michel_tavernier at hotmail.com Fri Apr 13 12:32:05 2001 From: michel_tavernier at hotmail.com (Michel Tavernier) Date: Mon Jan 9 13:41:01 2006 Subject: kordervoronoi Message-ID: Hi sir, My name is Michel 22years old and i am in my last year engineer in Belgium. I 'am making a thesis about computational geometry. More precisely programming computaional geometry figures in a java applet. I've already computed Delaunay triangulations, convex hulls,Voronoi diagrams,(largest and smallest) empty circles, constrained Delaunay triangulations and a few applications based on computational geometry such as topographic charts... The last thing I need is the higher order voronoi diagram. The last few months I tried to compute an own creation of an algorithm for the k-order voronoi (i made about 3500 java program lines).It only works for a second order voronoi in a very small amount of cases and it is very slow (it takes 4 minutes to do it for only 5 points). So I'm not a good inventor of algorithms but I needed to do it this way because nowhere in Belgium(highschool and university included) or on the internet I could find a book or a text describing a method for higher order Voronoi. It's also difficult to order a book such as international comp. geom. journal because i have no much time left and I can't afford it (I already spent about 250 dollars on books) My teacher suggested me to mail you. So you are my last hope,please can you help me. If you can mail me an article with an easy algorithm or in the best case java-code of the higher order Voronoi I would be very very grateful to you. Thank you! Greetings Michel. _________________________________________________________________________ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. ------------- The compgeom mailing lists: see http://netlib.bell-labs.com/netlib/compgeom/readme.html or send mail to compgeom-request@research.bell-labs.com with the line: send readme Now archived at http://www.uiuc.edu/~sariel/CG/compgeom/maillist.html. From dls at eecs.tufts.edu Sat Apr 14 18:46:57 2001 From: dls at eecs.tufts.edu (dls@eecs.tufts.edu) Date: Mon Jan 9 13:41:01 2006 Subject: ACM Symposium on Computational Geometry: On-line Registration is Enabled Message-ID: <200104142146.RAA11278@andante.eecs.tufts.edu> ON-LINE REGISTRATION IS AVAILABLE: http://www.eecs.tufts.edu/EECS/scg01/regform.html Early Discount through May 5, 2001 (Some resources are first-come-first-served) 17th Annual ACM Symposium on COMPUTATIONAL GEOMETRY June 3--5, 2001 Tufts University, Medford/Somerville, MA, USA INVITED SPEAKERS: Thomas Hales (University of Michigan): "Sphere Packings and Generative Programming" Fred Richards (Yale University): "Protein Geometry as a Function of Time" George W. Hart (http://www.georgehart.com): "Computational Geometry for Sculpture" ------------- The compgeom mailing lists: see http://netlib.bell-labs.com/netlib/compgeom/readme.html or send mail to compgeom-request@research.bell-labs.com with the line: send readme Now archived at http://www.uiuc.edu/~sariel/CG/compgeom/maillist.html. From krishnas at research.att.com Fri Apr 13 15:48:35 2001 From: krishnas at research.att.com (Shankar Krishnan) Date: Mon Jan 9 13:41:01 2006 Subject: kordervoronoi In-Reply-To: Message-ID: Here is a Java applet for higher order voronoi diagrams. http://www.msi.umn.edu/~schaudt/voronoi/voronoi.html Shankar Krishnan Member of Technical Staff AT&T Shannon Laboratory On Fri, 13 Apr 2001, Michel Tavernier wrote: > Hi sir, > > My name is Michel 22years old and i am in my last > year engineer in Belgium. > I 'am making a thesis about computational geometry. > More precisely programming computaional geometry figures > in a java applet. I've already computed Delaunay triangulations, > convex hulls,Voronoi diagrams,(largest and smallest) empty circles, > constrained Delaunay triangulations and a few applications based > on computational geometry such as topographic charts... > The last thing I need is the higher order voronoi diagram. The > last few months I tried to compute an own creation of > an algorithm for the k-order voronoi (i made about 3500 java program > lines).It only works for a second order voronoi in a very small amount > of cases and it is very slow (it takes 4 minutes to do it for only 5 > points). > So I'm not a good inventor of algorithms but I needed to do it > this way because nowhere in Belgium(highschool and university included) > or on the internet I could find a book or a text describing a method > for higher order Voronoi. > It's also difficult to order a book such as international comp. geom. > journal because i have no much time left and I can't afford it > (I already spent about 250 dollars on books) > My teacher suggested me to mail you. > So you are my last hope,please can you help me. > If you can mail me an article with an easy algorithm or in > the best case java-code of the higher order Voronoi I would > be very very grateful to you. > Thank you! > > Greetings Michel. > > > > _________________________________________________________________________ > Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. > > > ------------- > The compgeom mailing lists: see > http://netlib.bell-labs.com/netlib/compgeom/readme.html > or send mail to compgeom-request@research.bell-labs.com with the line: > send readme > Now archived at http://www.uiuc.edu/~sariel/CG/compgeom/maillist.html. > ------------- The compgeom mailing lists: see http://netlib.bell-labs.com/netlib/compgeom/readme.html or send mail to compgeom-request@research.bell-labs.com with the line: send readme Now archived at http://www.uiuc.edu/~sariel/CG/compgeom/maillist.html. From mulmuley at cs.uchicago.edu Mon Apr 16 16:15:30 2001 From: mulmuley at cs.uchicago.edu (Ketan Mulmuley) Date: Mon Jan 9 13:41:01 2006 Subject: kordervoronoi Message-ID: <20010416201530.9949B5394B@sloth.cs.uchicago.edu> I have one paper on a randomized algorithm for it: Discrete and Combinatorial Geometry, 6: 307-338 1991. See if that helps. all the best, ketan mulmuley. ------------- The compgeom mailing lists: see http://netlib.bell-labs.com/netlib/compgeom/readme.html or send mail to compgeom-request@research.bell-labs.com with the line: send readme Now archived at http://www.uiuc.edu/~sariel/CG/compgeom/maillist.html. From jsv at cs.duke.edu Mon Apr 16 19:18:04 2001 From: jsv at cs.duke.edu (Jeff Vitter) Date: Mon Jan 9 13:41:01 2006 Subject: Postdoctoral position at Duke Message-ID: <15067.28572.255036.20183@redbeans.cs.duke.edu> A postdoctoral position at the level of Visiting Assistant Professor of Computer Science is available starting August 2001 in the Department of Computer Science at Duke University, under the supervision of Prof. Jeff Vitter. The position, which is contingent upon grant funding, is for one year and can be extended for one or more additional years by mutual consent. Applicants must have clearly demonstrated experience and skills in algorithms design and implementation. Familiarity with external memory algorithms and indexing is a definite plus. Teaching responsibilities may include one research course per year. The position will include membership in the Center for Geometric and Biological Computing, a collaborative effort funded by the Army Research Office and the National Science Foundation. The problems of interest center around high-performance geometric and biological applications. They include development of efficient methods for spatial databases, geographic information systems, and indexing, especially those dealing with massive amounts of data. The candidate is expected to play a vital role in the development and/or use of the TPIE programming environment (http://www.cs.duke.edu/TPIE/) for external memory computation. Additional responsibilities will be to interact with agency scientists and to help prepare contract, technical, and other reports. Please send a letter of interest and your CV, and ask three evaluators to send letters of reference, by US Mail or email, to: Ms. Susan Clear ATTENTION: POSTDOC SEARCH Department of Computer Science Duke University Durham, NC 27708-0129 sclear@cs.duke.edu (919) 660-6548 To be assured of full consideration, all material including reference letters must arrive by April 30, 2001. Applications will be considered until the position is filled. Duke University is an affirmative action, equal opportunity employer. ------------- The compgeom mailing lists: see http://netlib.bell-labs.com/netlib/compgeom/readme.html or send mail to compgeom-request@research.bell-labs.com with the line: send readme Now archived at http://www.uiuc.edu/~sariel/CG/compgeom/maillist.html. From barequet at cs.Technion.AC.IL Thu Apr 19 16:56:42 2001 From: barequet at cs.Technion.AC.IL (Gill Barequet) Date: Mon Jan 9 13:41:01 2006 Subject: sweep in high dimensions Message-ID: <200104191256.PAA25498@cs.Technion.AC.IL> Dear geometers, I am looking for a working code for sweeping an arrangement of hyperplanes in a high-dimensional space. My specific application is to look for highly covered areas in a collection of (say, 30) halfspaces in 4-D or in 8-D. Thanks in advance, Gill. --------------------------------------------------------------------------- Gill Barequet Phone: +972-4-829-3219 Faculty of Computer Science Fax: +972-4-822-1128 (Rm.: [New] Taub 516) E-mail: barequet@cs.technion.ac.il The Technion---IIT WWW: http://www.cs.technion.ac.il/~barequet Haifa 32000 http://myprofile.cos.com/barequet Israel "Life is NP-Hard." (-) ------------- The compgeom mailing lists: see http://netlib.bell-labs.com/netlib/compgeom/readme.html or send mail to compgeom-request@research.bell-labs.com with the line: send readme Now archived at http://www.uiuc.edu/~sariel/CG/compgeom/maillist.html. From palios at zeus.cs.uoi.gr Wed Apr 25 21:54:52 2001 From: palios at zeus.cs.uoi.gr (Leonidas Palios) Date: Mon Jan 9 13:41:01 2006 Subject: triangulation verification Message-ID: <200104251754.UAA21842@zeus.cs.uoi.gr> Hello all. Some time ago, I came across a paper which dealt with the problem of verifying whether a given collection of triangles is a triangulation of a given polygon. The paper also addressed other verification problems (eg, delaunay triangulations, etc). Unfortunately, I do not recall the names of the authors, nor the exact title of the paper, and a (not very thorough) search on the Web did not produce anything. Does the above description ring a bell to any of you, so that I can locate that paper? Many thanks, Leonidas Palios ------------- The compgeom mailing lists: see http://netlib.bell-labs.com/netlib/compgeom/readme.html or send mail to compgeom-request@research.bell-labs.com with the line: send readme Now archived at http://www.uiuc.edu/~sariel/CG/compgeom/maillist.html. From Olivier.Devillers at sophia.inria.fr Thu Apr 26 09:32:43 2001 From: Olivier.Devillers at sophia.inria.fr (Olivier Devillers) Date: Mon Jan 9 13:41:01 2006 Subject: triangulation verification In-Reply-To: Your message of Wed, 25 Apr 2001 20:54:52 +0300. <200104251754.UAA21842@zeus.cs.uoi.gr> Message-ID: <200104260632.f3Q6WhK08245@polaire.inria.fr> > Some time ago, I came across a paper which dealt with the problem > of verifying whether a given collection of triangles is a triangulation > of a given polygon. The computational geometry bibliography can be download at ftp.cs.usask.ca query can be sent to http://www-ma2.upc.es/~geomc/geombib/geombibe.html http://www.cs.uu.nl/geobook/geom.html @article{mnssssu-cgpvg-99 , author = "K. Mehlhorn and S. N{\"a}her and M. Seel and R. Seidel and T. S chilz and S. Schirra and C. Uhrig" , title = "Checking Geometric Programs or Verification of Geometric Struct ures" , journal = "Comput. Geom. Theory Appl." , volume = 12 , number = "1--2" , year = 1999 , pages = "85--103" , succeeds = "mnssssu-cgpvg-96" , update = "99.07 } @article{dlpt-ccpps-98 , author = "Olivier Devillers and Giuseppe Liotta and Franco P. Preparata a nd Roberto Tamassia" , title = "Checking the Convexity of Polytopes and the Planarity of Subdiv isions" , journal = "Comput. Geom. Theory Appl." , volume = 11 , year = 1998 , pages = "187--208" , url = "http://www-sop.inria.fr/prisme/biblio/search.html" , keywords = "graph drawing, planar, straight-line, checking" , succeeds = "dlpt-ccpps-97" , cites = "-dcgs-, bbdgt-ccgg-97, bo-arcgi-79, bk-dpcw-95, b-ecvdl-96, c-t splt-91a, dtv-olcpt-95, dtv-olcpt-95t, dv-aptg-96, f-slrpg-48, glm-othsr-96, h-g t-72, ht-ept-74, k-eops-88, ll-abgtc-87, lpt-rpqid-97, lpt-rpqid-99, mn-cgs-96, mnssssu-cgpvg-96, mnssssu-cgpvg-97, swm-ccr-95, y-tegc-97" , update = "99.11 devillers, 99.03 devillers, 98.11 tamassia" , abstract = "This paper considers the problem of verifying the correctness o f geometric structures. In particular, we design simple optimal checkers for con vex polytopes in two and higher dimensions, and for various types of planar subd ivisions, such as triangulations, Delaunay triangulations, and convex subdivisio ns. Their performance is analyzed also in terms of the algorithmic degree, which characterizes the arithmetic precision required." } ------------- The compgeom mailing lists: see http://netlib.bell-labs.com/netlib/compgeom/readme.html or send mail to compgeom-request@research.bell-labs.com with the line: send readme Now archived at http://www.uiuc.edu/~sariel/CG/compgeom/maillist.html. From Olivier.Devillers at sophia.inria.fr Mon Apr 23 12:44:11 2001 From: Olivier.Devillers at sophia.inria.fr (Olivier Devillers) Date: Mon Jan 9 13:41:01 2006 Subject: Nuages reconstruction software announcement. Message-ID: <200104230944.f3N9iBo17013@polaire.inria.fr> The software NUAGES dealing with 3D reconstruction for cross sections. The source code of this software is now freely available for non commercial use. Thanks for your interest Olivier Devillers ftp://ftp-sop.inria.fr/prisme/NUAGES/Nuages/NUAGES_SRC.tar.gz --------------------------------------------------------------------------- O. Devillers, INRIA, 2004 route des Lucioles, BP 93, 06902 Sophia Antipolis Olivier.Devillers@sophia.inria.fr, +33 4 92 38 77 63, Fax +33 4 92 38 76 43 http://www-sop.inria.fr/prisme/personnel/devillers/ ------------- The compgeom mailing lists: see http://netlib.bell-labs.com/netlib/compgeom/readme.html or send mail to compgeom-request@research.bell-labs.com with the line: send readme Now archived at http://www.uiuc.edu/~sariel/CG/compgeom/maillist.html. From yjc at photon.poly.edu Sun Apr 22 17:15:46 2001 From: yjc at photon.poly.edu (Yi-Jen Chiang) Date: Mon Jan 9 13:41:01 2006 Subject: WADS 2001: list of accepted papers Message-ID: The following papers have been accepted to the 7th Workshop on Algorithms and Data Structures (WADS 2001), to be held August 8-10, 2001, at Brown University, Providence, Rhode Island, USA. For more information about the conference, please see the web page http://www.wads.org/. ------------------------ A Linear-Time Algorithm for Computing Inversion Distance Between Signed Permutations with an Experimental Study David A. Bader and Bernard M.E. Moret and Mi Yan Admission Control to Minimize Rejections Avrim Blum and Adam Kalai and Jon Kleinberg Fast fixed-parameter tractable algorithms for nontrivial generalizations of vertex cover Naomi Nishimura and Prabhakar Ragde and Dimitrios M. Thilikos A simple linear time algorithm for proper box rectangular drawings of plane grapghs Xin He Bin Packing with Item Fragmentation Nir Menakerman and Raphael Rom Minimizing clique-width for graphs of bounded tree-width Wolfgang Espelage and Frank Gurski and Egon Wanke Seller-Focused Algorithms for Online Auctioning A. Bagchi and A. Chaudhary and R. Garg and M. T. Goodrich and V. Kumar Upward Embeddings and Orientations of Undirected Planar Graphs Walter Didimo and Maurizio Pizzonia Using the pseudo-dimension to analyze approximation algorithms for integer programming Philip M. Long Higher-Dimensional Packing with Order Constraints S\'andor P. Fekete and Ekkehard K\"ohler and J\"urgen Teich Small Maximal Independent Sets and Faster Exact Graph Coloring David Eppstein Optimal Moebius Transformations for Information Visualization and Meshing Marshall Bern and David Eppstein On the Reflexivity of Point Sets E. M. Arkin and S. P. Fekete and F. Hurtado and J. S. B. Mitchell and M. Noy and V. Sacrist\'an and S. Sethia A decomposition-based approach to layered manufacturing Ivaylo Ilinkin and Ravi Janardan and Jayanth Majhi and Joerg Schwerdt and Michiel Smid and Ram Sriram Computing Phylogenetic Roots with Bounded Degrees and Errors Zhi-Zhong Chen and Tao Jiang and Guo-Hui Lin A (7/8)-approximation algorithm for metric Max TSP Refael Hassin and Shlomi Rubinstein Approximating Multi-Objective Knapsack Problems Thomas Erlebach and Hans Kellerer and Ulrich Pferschy Visual Ranking of Link Structures Ulrik Brandes and Sabine Cornelsen Complexity Bounds for Vertical Decompositions of Linear Arrangements in Four Dimensions Vladlen Koltun Search Trees with Relaxed Balance and Near-Optimal Height Rolf Fagerberg and Rune E. Jensen and Kim S. Larsen Voronoi Diagrams for Moving Disks and Applications Menelaos I. Karavelas Reporting Intersecting Pairs of Polytopes in Two and Three Dimensions P. K. Agarwal and M. de Berg and S. Har-Peled and M. Overmars and M. Sharir and J. Vahrenhold Time Responsive External Data Structures for Moving Points Pankaj K. Agarwal and Lars Arge and Jan Vahrenhold The Grid Placement Problem P. Bose and A. Maheshwari and P. Morin and J. Morrison An Approach for Mixed Upward Planarization Markus Eiglsperger and Michael Kaufmann Short and simple labels for small distances and other functions Haim Kaplan and Tova Milo Competitive analysis of the LRFU paging algorithm Edith Cohen and Haim Kaplan and Uri Zwick I/O-Efficient Shortest Path Queries in Geometric Spanners Anil Maheshwari and Michiel Smid and Norbert Zeh When Can You Fold a Map? E. M. Arkin and M. A. Bender and E. D. Demaine and M. L. Demaine and J. S. B. Mitchell and S. Sethia and S. S. Skiena Optimal, Suboptimal and Robust Algorithms for Proximity Graphs F. Hurtado and G. Liotta and H. Meijer On External-Memory Planar Depth First Search Lars Arge and Ulrich Meyer and Laura Toma and Norbert Zeh Movement Planning in the Presence of Flows John Reif and Zheng Sun The Analysis of a Probabilistic Approach to Nearest Neighbor Searching Songrit Maneewongvatana and David M. Mount Optimization Over Zonotopes and Training Support Vector Machines Marshall Bern and David Eppstein Practical Approximation Algorithms for Separable Packing Linear Programs F.F. Dragan and A.B. Kahng and I.I. Mandoiu and S. Muddu Two-Guard Walkability of Simple Polygons Binay Bhattacharya and Asish Mukhopadhyay and Giri Narasimhan Fast Boolean matrix multiplication for highly clustered data Andreas Bjorklund and Andrzej Lingas On the Complexity of Scheduling Conditional Real-Time Code Samarjit Chakraborty and Thomas Erlebach and Lothar Thiele Succinct Dynamic Data Structures Rajeev Raman and Venkatesh Raman and S. Srinivasa Rao Partitioning colored point sets into monochromatic parts Adrian Dumitrescu and Janos Pach ------------- The compgeom mailing lists: see http://netlib.bell-labs.com/netlib/compgeom/readme.html or send mail to compgeom-request@research.bell-labs.com with the line: send readme Now archived at http://www.uiuc.edu/~sariel/CG/compgeom/maillist.html. From jardine at uwo.ca Thu Apr 26 21:34:09 2001 From: jardine at uwo.ca (jardine@uwo.ca) Date: Mon Jan 9 13:41:01 2006 Subject: Stanford conference, July 30 - August 3 Message-ID: <3AE8BE81.2DC271F@uwo.ca> -------------- next part -------------- Third Announcement: Conference on Algebraic Topological Methods in Computer Science Stanford University July 30 - August 3, 2001 This meeting is supported by grants from the National Science Foundation, the Natural Sciences and Engineering Research Council of Canada, the Fields Institute, Hewlett-Packard, and the Stanford Department of Mathematics. The most up to date information on the conference appears on the conference web page http://math.stanford.edu/atmcs/index.htm. Housing is still available on campus at a cost of about 50.00 US per night. The deadline for registering for on campus housing at Stanford is *May 1, 2001*. There is a registration form available as a pdf file, to be printed, filled out and faxed to the Stanford Summer Conference Services office. There is also a short registration for the conference itself at that web page. If you are coming to the conference and have not yet registered for the conference, please do so. There will be no registration fee. Limited financial support may be available for travel and housing. Please make your request when registering for the conference. The following have agreed to speak at this meeting: John Baez (Math, UC Riverside) Marshall Bern (Xerox PARC) Anders Bjorner (Royal Institute of Technology, Stockholm) Tamal Dey (CS, Ohio State) Herbert Edelsbrunner (CS, Duke) David Eppstein (CS, UC Irvine) Michael Freedman (Microsoft) Philippe Gaucher (CNRS, Strasbourg) Eric Goubault (Commissariat a l'Energie Atomique, France) Jean Goubault-Larrecq (ENS Cachan) Marco Grandis (Dip. di Mat., Genova) Jeremy Gunawardena (HP BRIMS) John Harer (Math, Duke) Joel Hass (Math, UC Davis) Maurice Herlihy (CS, Brown) Reinhard Laubenbacher (Math, NMSU) Laszlo Lovasz (Microsoft) Vaughan Pratt (CS, Stanford) Christian Reidys (Los Alamos National Lab) Bernd Sturmfels (Math, UC Berkeley) Noson Yanofsky (CS, Brooklyn College) There will be some time for contributed talks. If you would like to give a short talk at the meeting, please send a title and abstract to one of the organizers. The organizers for this meeting are: Gunnar Carlsson: gunnar@math.stanford.edu Rick Jardine: jardine@uwo.ca From biedl at math.uwaterloo.ca Fri Apr 27 12:54:31 2001 From: biedl at math.uwaterloo.ca (Therese Biedl) Date: Mon Jan 9 13:41:01 2006 Subject: CCCG'01 - Last Call for Papers - Deadline April 30th Message-ID: -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Last Call for Papers 13th Canadian Conference on Computational Geometry August 13-15, 2001 University of Waterloo http://compgeo.math.uwaterloo.ca/~cccg01 -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Objectives ========== The Canadian Conference on Computational Geometry (CCCG) focuses on the mathematics of discrete geometry from a computational point of view. Abstracting and studying the geometry problems that underly important applications of computing (such as geographic information systems, computer-aided design, simulation, robotics, solid modeling, databases, and graphics) leads not only to new mathematical results, but also to improvements in these applications. Despite its international following, CCCG maintains the informality of a smaller workshop and attracts a large number of students. Call for Papers =============== Authors are invited to submit papers describing research of theoretical and practical significance to computational geometry. Electronic submissions, in standard PostScript and not exceeding 4 pages length, should be made from the conference web page. A special issue of Computational Geometry: Theory and Applications will be devoted to invited papers from the conference. Program Committee ================= Therese Biedl (Univ. of Waterloo) Timothy Chan (Univ. of Waterloo) Erik Demaine (Univ. of Waterloo) David Kirkpatrick (UBC) Anna Lubiw (Univ. of Waterloo) Joseph O'Rourke (Smith College) Godfried Toussaint (McGill University) Organizing Committee ==================== Therese Biedl (Univ. of Waterloo) Erik Demaine (Univ. of Waterloo) Martin Demaine (Univ. of Waterloo) Anna Lubiw (Univ. of Waterloo) Important dates =============== Submission of papers: April 30, 2001 Notification of acceptance: May 29, 2001 Submission of final paper: June 29, 2001 Conference: August 13-15, 2001 Contact Information =================== Therese Biedl Dept. of Computer Science University of Waterloo Waterloo, ON N2L 3G1 Phone: (519) 888-4567x4721 Fax: (519) 885-1208 Email: biedl@uwaterloo.ca Sponsors ======== CCCG '01 is supported by CRM, The Fields Institute, PIMS and the University of Waterloo. ------------- The compgeom mailing lists: see http://netlib.bell-labs.com/netlib/compgeom/readme.html or send mail to compgeom-request@research.bell-labs.com with the line: send readme Now archived at http://www.uiuc.edu/~sariel/CG/compgeom/maillist.html. From brd at snow.cs.dartmouth.edu Sun Apr 29 21:18:45 2001 From: brd at snow.cs.dartmouth.edu (Bruce Randall Donald) Date: Mon Jan 9 13:41:01 2006 Subject: Postdoc in Computational Biology Message-ID: <200104292018.UAA39648@snow.cs.dartmouth.edu> Dartmouth College Department of Computer Science Postdoctoral Research Associate in Computer Science: (One, or possibly two positions open). We are looking for persons with a doctorate in computer science to conduct focused research in computational biology, specifically, on computational structural biology and computer-aided drug design. The position involves a two-year appointment which may be extended depending on funding. The research has two parts: (1) geometric algorithms and systems for drug design and (2) the automated interpretation of high-throughput structural data for proteins and protein-protein complexes (e.g., from NMR or mass spectrometry). A wealth of fascinating computational problems arise in computer-aided drug design and structural proteomics. For more on this position, our research, job placement for Donald Lab alumni, and life at Dartmouth, see http://www.cs.dartmouth.edu/~brd/Jobs/. Applicants for this position must hold a PhD in Computer Science or a related discipline, or show evidence that the PhD will be completed before the start of the position. Applicants should send a resume and have at least two referees send letters of recommendation to Prof. Bruce Randall Donald, Dept. of Computer Science, Dartmouth College, 6211 Sudikoff Laboratory, Hanover, NH 03755-3510, brd@cs.dartmouth.edu, http://www.cs.dartmouth.edu/~brd/. Electronic submissions are encouraged, although I greatly prefer ascii text to enclosures. Dartmouth College is an Equal Opportunity Affirmative Action employer. ------------- The compgeom mailing lists: see http://netlib.bell-labs.com/netlib/compgeom/readme.html or send mail to compgeom-request@research.bell-labs.com with the line: send readme Now archived at http://www.uiuc.edu/~sariel/CG/compgeom/maillist.html.