|> I am looking for an Algorithm, which is capable to generate "iso"-Lines

|> out of a set of points. That means:

|> I have a number of Points, e.g. X/Y and pressure. In this case i want to

|> generate isobares (is this the correct term). I tried to interpret pressure

|> as z-value and generated triangles. Then i computete the intersection between

|> a Plane of constant z and the triangles. The Result: Lines of equal pressure.

|> But: The lines are ugly because they consist of straight segments. For a

|> map-like plot i need smooth curves. I tried splines, but there are cases, when

|> those splines intersect. Any solution out there?

|> Ciao, Udo

You will find some answers in my book -

CONTOURING: A guide to the analysis and display of spatial data,

Pergamon Press, 1992, ISBN 0 08 040286 0

This book catalogues and categorizes all the published methods I could

find and has about 600 references. The code that comes with the book

implements 18 interpolation methods, 5 gradient estimation methods, and

7 display methods. Apparently the most useful, reliable, and general,

method is natural neighbour interpolation. This is a relatively unknown

weighted average method using a variable number of area-based local

coordinates.

Details of a commercial gridding program using natural neighbour

interpolation is available by email from the undersigned.

--

Department of Mathematics Tel: (61 9) 380 3359

The University of Western Australia FAX: (61 9) 380 1028

Nedlands, WA 6009 Australia. Real data are full of surprises