Feature Description

Spline interpolation uses a mathematical expression of minimal surface curvature to simulate and generate a smooth surface passing through a series of sample points.

• The source dataset used for interpolation must contain a numeric field as the interpolation field.
• Spline interpolation is suitable for scenarios requiring interpolation calculations with large sample points and smooth surface generation. More input points produce smoother surfaces, though higher point counts increase raster processing time.
• The fixed-length spline function method creates gradually smooth surfaces using values that may extend beyond the sample layer bounds. The variable-length spline method controls surface hardness based on phenomenon characteristics, creating less smooth surfaces constrained within sample layer bounds.

Feature Entry

• Spatial Analysis Tab->Raster Analysis group->Interpolation Analysis->Spline.
• Toolbox->Raster Analysis->Interpolation Analysis->Spline.

Parameter Description

Fixed Count: Uses a fixed number of sample points within maximum radius for interpolation.

Fixed Radius: All points within search radius participate in interpolation.

Block: Divides dataset using "Maximum Points Per Block", then performs interpolation within blocks.

Spline Interpolation Result

• Configure common interpolation analysis parameters including source data, bounds, result data and environment settings. For parameter details see: Common Parameter Description.
• Set sample point search methods: Fixed Count, Fixed Radius, or Block Search. For details see: Spline Interpolation.
  • Maximum Radius: Input radius value for fixed count. Default 0 indicates using maximum search radius.
  • Search Points: Input number of points for fixed count. Default is 12.
  • Search Radius: Input search radius. Default is 1/5 of the longer side length of dataset extent.
  • Minimum Points: Input minimum points required. Default 5. Search radius expands until containing specified minimum points. Maximum 12.

  Parameters "Maximum Interpolation Points" and "Maximum Points Per Block" directly affect block search performance. Higher values increase processing time. Set reasonable values for optimal performance.

  • Maximum Interpolation Points: Input maximum interpolation points. Default 200. Actual calculation blocks expand outward, determined by this parameter. Should generally exceed "Maximum Points Per Block".
  • Maximum Points Per Block: Input maximum points per block. Default 50. Blocks exceeding this value will be subdivided.
• Tension: Input tension value (default 40). Controls raster surface characteristics. Higher tension reduces individual point influence.
• Smoothness: Input smoothness value (0-1, default 0.1). Determines curve fitting accuracy. Higher values increase deviation from points.