# Lisp for autocad linear interpolation

The aim of this application is to integrate the specific database for those 3D models that for some reason or another give a poor performance. The application is addressed to professionals who, while developing their projects, need an accurate study and a detailed 3-D model of the field

The application includes two different methods of interpolation:

• Linear interpolation between three-dimensional points
• Interpolation between weighted mean three-dimensional points

## Linear interpolation between three-dimensional points

In this case the classical method for linear interpolation between two three-dimensional points is used where:

• zx = is the value of the linear interpolated point
• i = is the slope between two points (concerned by the linear interpolation)
• d = is the distance between two points concerned by the linear interpolation

alternatively : • Zn = is the value of the linear interpolated point
• Zx1 = this is the elevations value of the first known point for the interpolation
• Zx2 = this is the elevations value of the second known point for the interpolation
• Dx2Dx1 = this is the distance between two points concerned by the linear interpolation
• Dx1Dx1 = this is the distance between the first point in the linear interpolation and itself (is always zero)
• Dx1Dxn = this is the distance between the first point concerned by the linear interpolation and the point to interpolate

The possible options are:
Managing an increasing amount of points to interpolate
The position of the interpolated point may be modified manually, by means of a reactor which shows on a graph the geometric position of the interpolated point.

### Interpolation between weighted mean three-dimensional points

In this case, the equation to calculate the weighted mean of the point will be applied. where:

• zx = is the value of the interpolated point
• n = is the numbers of the points selected for the interpolation (radius value is the area of selection)
• z = is the elevation of the points inside the radius of selection (all points concerned by the interpolation)
• d = is the distance between the intersected point and the points concerned by the interpolation
• k = kriging value of the interpolation

The possible options are:
to select the points to be included in the interpolation by means of a range around the spot to be created by the interpolation, the range being defined by the operator.
to select manually at least three points to be included in the interpolation
to obtain a preview of the selected range to be included in the interpolation
to assign the Kriging value.   