Re: need help!!
Michael T. Jones (mtjones++at++ix.netcom.com)
Sun, 30 May 1999 11:15:32 -0700
At 11:24 PM 5/30/99 +0800, lf60505 wrote:
|Dear Sir:
|I am a chinese graduate student,now I have a question: given a series of sample points(maybe several |thousand),how can I draw a 3-d scene such as surface of a mountain?
|it's ergently,so I wish a quick reply.
|thank you very much!
|sincerely yours.
Here's your quick reply.
It seems that you are not satisfied with converting the points into a pfGeoSet and
drawing that, but if you did, and you move the resulting point-surface interactively,
you will be able to see and understand the data. The human mind is quite amazing
when interpreting moving correlated images. I only mention this because if you are
really in a hurry, this might be better than you think and it's very easy.
Your real goal, though, is to convert your point set into a mesh of triangles with the
points as the vertices. This is a widely studied problem with many different types of
solutions. There are solutions in the "Graphics Gems" books, in computational
geometry books, and in many other sources (ACM collected algorithms, etc.)
A good place to begin (and likely the choice you'll make for your terrain project)
is the technique known as "Delauney Triangulation" which connects points to
nearest neighbors. Source code is available from many places.
I recommend that you begin by reading about and using Triangle, by Johnathan
Shewchuk: http://www.cs.cmu.edu/~quake/triangle.html, and also read the URL
http://www.mhri.edu.au/~pdb/modelling/triangulate/ which has diagrams,
text, and c-code; and http://www.lec.leeds.ac.uk/~jason/Mesh_Generation/
which has links to everything. These have references that will help you learn more,
but if you want to just solve your urgent visualization problem, start with Triangle
and you can have this working in a day.
Regards,
Michael "Triangulation" Jones
----------
Michael T. Jones - <mailto:mtj++at++intrinsic.com>mtj++at++intrinsic.com - <http://www.intrinsic.com/>Intrinsic Graphics Inc. - (408) 507-8160
A frog in a well says "The sky is as big as the mouth of my well"
At 11:24 PM 5/30/99 +0800, lf60505 wrote:
|Dear Sir:
|I am a chinese graduate student,now I have a question: given a
series of sample points(maybe several |thousand),how can I draw a 3-d
scene such as surface of a mountain?
|it's ergently,so I wish a quick reply.
|thank you very much!
|sincerely yours.
Here's your quick reply.
It seems that you are not satisfied with converting the points into
a pfGeoSet and
drawing that, but if you did, and you move the resulting
point-surface interactively,
you will be able to see and understand the data. The human mind is
quite amazing
when interpreting moving correlated images. I only mention this
because if you are
really in a hurry, this might be better than you think and it's very
easy.
Your real goal, though, is to convert your point set into a mesh of
triangles with the
points as the vertices. This is a widely studied problem with many
different types of
solutions. There are solutions in the "Graphics Gems"
books, in computational
geometry books, and in many other sources (ACM collected algorithms,
etc.)
A good place to begin (and likely the choice you'll make for your
terrain project)
is the technique known as "Delauney Triangulation" which
connects points to
nearest neighbors. Source code is available from many places.
I recommend that you begin by reading about and using Triangle, by
Johnathan
which has links to everything. These have references that will help you learn more,
but if you want to just solve your urgent visualization problem, start with Triangle
and you can have this working in a day.
Regards,
Michael "Triangulation" Jones
Michael T. Jones - mtj++at++intrinsic.com - Intrinsic Graphics Inc. - (408) 507-8160
- A frog in a well says "The sky is as big as the mouth of my well"
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on Sun May 30 1999 - 11:14:58 PDT