16.6 3D Interpolation



3D Interpolation tool uses a smooth function Q(x,y,z), which is a modification of Shepard's method, to interpolate m scattered data points. You can specify the X/Y/Z Minimum and Maximum and number of interpolation points in each dimension for 3D interpolation.

To Use 3D Interpolation Tool
  1. Create a new worksheet with X, Y, Z (data) columns, plus a fourth column of values each of which is associated by row index number with a set of XYZ coordinates.
  2. Activate the worksheet.
  3. Select Analysis: Mathematics: 3D Interpolation. This opens the interp3 dialog box.
  4. Choose your input and output options and click OK. The X-Function interp3 is called to perform the calculation.

Dialog Options


Controls recalculation of analysis results

  • None
  • Auto
  • Manual

For more information, see: Recalculating Analysis Results


Specify the input data range.

  • X
    Select one X column.
  • Y
    Select one Y column.
  • Z
    Select one Z column.
  • F
    Select one 3D function column.

For help with range controls, see: Specifying Your Input Data

Computation Control

Specify parameters of interpolated points.

Number of Points in Each Dimension
The number of interpolated points in each dimension.
X Minimun
Specify the X minimun value of this interpolation.
X Maximun
Specify the X maximun value of this interpolation.
Y Minimun
Specify the Y minimun value of this interpolation.
Y Maximun
Specify the Y maximun value of this interpolation.
Z Minimun
Specify the Z minimun value of this interpolation.
Z Maximun
Specify the Z maximun value of this interpolation.

The output result for the interpolated data.


This function constructs a smooth function Q(x,y,z)\! which interpolates a set of m\! scatter data points (x_r,y_r,z_r,f_r)\! for r= 1, 2, ... , m\!, using a modification of Shepard's method. It then evaluates the interpolant at the set of selected points (u_r,v_r,w_r)\!, as well as its first partial derivatives. The surface is continuous and has continuous first partial derivatives.

Q(x,y,z)=\frac{ \sum \omega _r(x,y,z)q_r}{ \sum \omega _r(x,y,z)}



For more information on algorithms, please see documentation for these NAG functions:


For reference information, please see documentation for these NAG functions: