How does the contour tool (3D Anaylst) work in detail?

Question

Hello,

can anybody give me additional information on how contouring (3D Analyst) in ArcGIS works?

Looking at the explanations within the help files I got no satisfying answer. I derived a contour from a raster with a resolution of 1 m and a base contour located at 0.05 m above mean sea level.

Is it a TIN-interpolation based on the cell center points? I wonder why the distances between the vertices (contour) are so irregular...

Any information on how the contour-tool works in detail would be great!

Best regards

Thorsten Dey

this is how it looks like...

SteveLynch · Accepted Answer

We have a raster with pixel values = 799; 802; 791, etc. and we want a contour line at 830 (for example).

The algorithm bisects each pixel and calculates the value at each node (814; 809; 838; 834).. It'll then determine where on these lines the value=830 (see red dots) and then finally construct the polyline which is the 830 contour.

Contouring is like slicing a potato, each slice = contour 🙂

This applies to the Contour tool in Spatial/3D Analyst.