graphics: CONTOUR-PARAMETERS

BISECTION-ITERATIONS

The maximum number of bisections that is allowed to find a coarse starting point for a new contour between 2 grid points.

Small values are recommended since a Newton search anyhow refines the starting point.

[Default: 10]

EPSILON-GRADIENT

The \ε used to compute the gradient.

For coordinates near 0, this is the absolute sampling size. For large coordinates, the parameter is taken relative.

When the area is very small (e.g. around 10\<SUP\>-3\</SUP\>) or when there is a lot of structure in the contours, then it is a good idea to reduce the value of this parameter to e.g. 10\<SUP\>-4\</SUP\>.

[Default: 10\<SUP\>-3\</SUP\>]

EPSILON-TRACING

The \ε used to follow a contour perpendicularly to the gradient.

For coordinates near 0, this is the absolute step size. For large coordinates, the parameter is taken relative.

When the area is very small (e.g. around 10\<SUP\>-3\</SUP\>) or when the contours make sharp bends, then it is a good idea to reduce the value of this parameter to e.g. 10\<SUP\>-4\</SUP\>.

[Default: 10\<SUP\>-3\</SUP\>]

GRID-TOLERANCE

Since the contours are computed as piecewise straight lines while the true contour is curved, it can be that a computed segment does not pass between the same grid points where the true contour passes.

In such cases, the algorithm checks whether the contour passes near a grid point within a certain fraction of the grid size, set with this option.

This parameter rarely needs updating. If the parameter is too small, then some contours will be drawn twice. Contours are not missed due to a poor setting of this parameter.

[Default: 0.1]

NEWTON-ITERATIONS

Maximum number of Newton iterations when refining the starting point of a contour and when finding the contour back after a step perpendicular to the gradient.

[Default: 10]

STEP-MAXIMUM

Maximum number of steps in any single contour.

If this parameter is too small, then the contours will be drawn as a series of overlapping pieces.

[Default: 500]

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Formatted on 21/01/18 at 16:55.