Converting Bathymetry data into a contour map

I am trying to find a piece of software on the net that I can use to convert a large set of bathymetry data into a contour map. The data that I have consists of 20000 points with x and y co-ordinates, each with a listed depth. They are in no particular order. [It is a set of measurements taken by boat in a harbour basin.] I need a piece of software that can convert this data into a contour map showing the depths across the basin. Extensive net searching has yielded nothing so far! [sig][/sig]

 

[georam]

If it is just for a contour maps, I think a small program similar to "Surfer" software would be adequate. It used to be a DOS program, relatively small, but quick. However, nowadays it is available for windows version, and it is not free. You may enter the x,y and z coordinates from spreadsheet tables or free format files.
Check their website

http://www.goldensoftware.com

Hope that this helps

 

[TimC]

There should be several shareware and/or freeware programs available on the web. Simtel would be a good start. COGS (Computer Oriented Geological Society -- now inactive) had a few DOS programs in their package of free offerings. I know their package is available over the net through one of the geology groups. USGS has some viewers for the DEM format (which is essentially nothing more than x, y, z data). The best Windows-based general package is Surfer from Golden Software -- which is what I have used for years. The generated contours are based on a powerful statistical analysis of the data patterns and the results are generally very close to reality. They do have a downloadable demo on their web-site but I don't know if the demo would handle a dataset of your size.

In searching the web for software, try using keywords such as:

topo, grid, gridding, contouring, USGS, DEM, mapping, download

Also, many of the 3-d enabled cadd programs have facilities for importing x-y-z data and building a mesh -- but not necessarily doing the actual contouring. Also, you might want to contact a local surveyor or a nearby general civil engineering firm -- they usually have facilities for generating and plotting contour maps.