Generate DBH Inversion Model

Function Overview

Generate DBH Inversion Model builds a DBH estimation model from individual tree attribute files that contain tree height, crown width, and measured DBH. The tool fits the selected formula by least squares, saves the formula and model coefficients to a *.dbhim file, and records the fitting information in the processing log.

Usage

Click ALS Forest > Individual Tree Attributes > Generate DBH Inversion Model to open the tool.

Steps

Add an individual tree attribute file (*.treedb) that contains measured DBH values.
Select the formula used for model fitting.
Set the output path and model name.
Click OK to generate the DBH inversion model.
Use the generated model in DBH Inversion.

Parameter Settings

Individual Tree Attribute File: Input *.treedb file used as the fitting sample. The file must contain tree height, crown width, and measured DBH.
Model Formula: Formula used to fit DBH from tree height and crown width.
Output Path: Folder used to save the generated model file.

Supported Formulas

The following formulas are supported. D is DBH, H is tree height, CW is crown width, and a, b, c, d, e, f, and u_i are model coefficients.

D = a * CW + b * H + c
ln(D) = a + b * ln(H)
ln(D) = a + b * ln(CW)
ln(D) = a + b * ln(H * CW)
ln(D) = a + b * ln(H) + c * ln(CW)
ln(D) = a + b * CW
D = a + b * CW
D = a + CW^b
D = a * ln(CW) + b
D = a + b * CW + c * CW * CW
D = a * CW * CW + b * CW + c * H + d * H * H + e * CW * H + f
D = a / (1 + b * exp(-(c * H + d * CW)))
D = a * exp(b * H + c * CW)
D = a * H^b * CW^c
D = a * H^b * CW^c + d
D = a * H^b * CW^c + u_i

Output

The tool outputs a DBH inversion model file (*.dbhim) and writes the fitting result to the processing log.

Notes

Use representative measured DBH samples to improve model reliability.
Select a formula that matches the tree species, stand type, and survey requirements.

Generate DBH Inversion Model