Interpolation Options

Use the Interpolation Options dialog to fill gaps in grids prior to stitching. This can improve suture path selection in grids containing missing data. This option is not intended for general-purpose grid interpolation.

Interpolation Options dialog options

Interpolation method

Select the interpolation method to use:

  • Linear

  • Cubic

  • Akima (default)

Script Parameter: GRIDSTCH.SPLINE

Maximum interpolated gap

Specify the maximum gap size (in cells) that will be interpolated.

If left blank, no interpolation is performed (default behaviour).

See the Application Notes below for more details.

Script Parameter: GRIDSTCH.GAP

Application Notes

Grids may contain gaps (missing data) within overlapping regions. These gaps can affect stitching behaviour:

  • In the Blend method, gaps are treated as grid edges, so the contribution of a grid containing a gap is reduced to zero at the gap boundaries.

  • In the Suture method, the automatic suture path tends to avoid gaps, as it is positioned midway between grid edges.

These effects may be reduced or eliminated by interpolating gaps prior to stitching.

Maximum Interpolated Gap

Gap size is specified in cell units.

  • If set to a value X, all gaps smaller than X cells are interpolated prior to stitching.

  • If set to 0.0, all gaps are interpolated.

  • If not specified, no interpolation is performed.

Using a value of 0.0 may produce undesirable results when large "bays" are present (for example, streaking artifacts in filled areas of the output grid).

Interpolation Method

The interpolation method determines how values are estimated within gaps:

  • Linear – Assumes a simple linear variation between the values bounding the gap.

  • Cubic – Uses a minimum curvature approach.

  • Akima – Reduces overshoot in areas with rapid gradient changes, but may produce sharper transitions.

The cubic method may introduce artificial highs or lows in areas where the data changes rapidly. This most commonly occurs across lines with poor line-to-line data correlation.

The Akima method is less prone to this issue. However, it tends to produce sharper corners around actual data points, and the resulting grid may be less smooth.

The interpolation method used here operates strictly across rows and columns and is therefore less robust than more advanced gridding methods (such as minimum curvature). For best results, perform full interpolation either before or after stitching using dedicated gridding tools.

Trend Processing

Trend calculation and removal are performed after interpolation.

See Also: