Computree Documentation

3 - Estimation of the Plant Area Density

Plugin : LVOX
Nom de classe : LVOX3_StepComputePAD

Description

Step allowing the computation of the Plant Area Density (PAD) for a grid set.
The field "Attenuation coefficient estimators method" allows choosing between multiple computation methods :
  • Contact Frequency : CF
  • Beer-Lambert : BL
  • Maximum Likelyhood Estimator : MLE
  • Bias-Corrected Maximum Likelyhood Estimator : BCMLE
  • Bias-Corrected Beer-Lambert (Equal path) : BCBL
  • Bias-Corrected Beer-Lambert (Unequal path) : BC2BL
Note that Beer-Lambert as well as MLE are obsolete in term of precision but are left to allow baseline comparisons

Users can also set a threshold for the actual hits (N = Nt - Nb) in a voxel (ie. if a For more informations regarding the different methods used to compute the PAD, refer to the provided article.

Paramètres

Step parameters:
  • Attenuation coefficient estimators method: String with the following possible values =
    • Contact Frequency : CF
    • Beer-Lambert : BL
    • Maximum Likelyhood Estimator : MLE
    • Bias-Corrected Maximum Likelyhood Estimator : BCMLE
    • Bias-Corrected Beer-Lambert (Equal path) : BCBL
    • Bias-Corrected Beer-Lambert (Unequal path) : BC2BL
  • Compute estimator for N larger than: integer default = 5
  • Use relative threshold: booleandefault = false
  • Create grids corresponding to summations: booleandefault = false

Données d'entrée

Structure des données d'entrée recherchées :

Result : SGrids
    ...
        Group (Group)
            Hits (3D grid LVOX)
            Theoretical (3D grid LVOX)
            Before (3D grid LVOX)

Données de sortie


Group [Group]:
...
One or many of the follwing, given the "Attenuation coefficient estimators method" selected :
LVOX3_Grid3D [PAD-ContactFreq]
LVOX3_Grid3D [PAD-MLE]
LVOX3_Grid3D [PAD-BiasCorMLE]
LVOX3_Grid3D [PAD-BeerLamb]
LVOX3_Grid3D [PAD-BiasCorBeerLamb]
LVOX3_Grid3D [PAD-UnequalPathBeerLamb]
If "Create grids corresponding to summations" is checked, all of the following will be produced :
LVOX3_Grid3D [FreePath Sum]
LVOX3_Grid3D [Effective FreePath Sum]
LVOX3_Grid3D [Delta Sum]
LVOX3_Grid3D [Effective Delta Sum]
LVOX3_Grid3D [Effective Delta Square Sum]
LVOX3_Grid3D [1_zleDelta Effective Sum]

Références

Nguyen Van-Tho, Fournier Richard A., Côté Jean-François, Pimont François. 2022. Estimation of vertical plant area density from single return terrestrial laser scanning point clouds acquired in forest environments. Remote Sensing of Environment. https://www.sciencedirect.com/science/article/pii/S0034425722002292.