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.
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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/ |
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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
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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/ |
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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/ |
>
>
>
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>
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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
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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.
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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
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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.
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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"
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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.
>
>
> -------------
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> Now archived at http://www.uiuc.edu/~sariel/CG/compgeom/maillist.html.
>
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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.
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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.
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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." (-)
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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
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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."
}
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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/
-------------
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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
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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.
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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.
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