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Ispra, 26/2/2008 1/21 SOIL Action Meeting, 04/03/2008 The OSACA Web Application A B D(A;B) Concepts and applications.

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Presentation on theme: "Ispra, 26/2/2008 1/21 SOIL Action Meeting, 04/03/2008 The OSACA Web Application A B D(A;B) Concepts and applications."— Presentation transcript:

1 Ispra, 26/2/2008 1/21 SOIL Action Meeting, 04/03/2008 The OSACA Web Application A B D(A;B) Concepts and applications

2 Ispra, 26/2/2008 2/21 SOIL Action Meeting, 04/03/2008 OSACA finalities To classify soil observations into soil types (ST) or clusters (soil classification tool) Soil observations Soil types To allocate soil observations according to soil types provided by the user Soil observations To classify soil observation horizons into horizon types (id. ) Users soil types + Range of ST required - Table of distances between observations and ST - Description of ST - Table of distances between ST - Quality of the classification - Table of distances between observations and ST - Table of distances between ST inputs outputs inputs

3 Ispra, 26/2/2008 3/21 SOIL Action Meeting, 04/03/2008 The classification process Min. # Soil Type centroids Calculation of distances Calculation of new centroids D intra /D inter ratio Min+1. # Soil Type centroids Max. # Soil Type centroids Initialisation of cluster centroids Observation allocation Centroid readjustment Optimisation process optimization K-means techniques

4 Ispra, 26/2/2008 4/21 SOIL Action Meeting, 04/03/2008 Initialisation of centroids NC Soil Types or Clusters being required by the user, we fix γ an initial large distance Pick up randomly 2NC observations Calculate the distance between the 2NC observations If distance < γ, choose other observations and go to, otherwise go to Calculate distance between the whole set of observations and the 2NC observations, and allocate the corresponding observations (those with d min ) Sort by decreasing order of population the 2NC clusters If more than NC clusters are empty, γ = γ/2 and go to, otherwise, choose the NC first ones and consider the corresponding centroids as initial centroids

5 Ispra, 26/2/2008 5/21 SOIL Action Meeting, 04/03/2008 The classification process Min. # Soil Type centroids Calculation of distances Calculation of new centroids D intra /D inter ratio Min+1. # Soil Type centroids Max. # Soil Type centroids Initialisation of cluster centroids Observation allocation Centroid readjustment Optimisation process optimization K-means techniques

6 Ispra, 26/2/2008 6/21 SOIL Action Meeting, 04/03/2008 Calculation of distances OSACA provides 3 kinds of distances useful for different purposes Pedological distance for emphasizing the different succession of horizons whatever their thickness Utilitarian or environmental distance for emphasizing the successions of horizons for which the thickness is important Joint or normalised distance is a mixed between the two previous distances

7 Ispra, 26/2/2008 7/21 SOIL Action Meeting, 04/03/2008 D(x,A) D(y,B) D(z,C) 0 cm 20 cm 60 cm 120 cm A B C Centroid Pedological distance D (# D) Calculation of distances x y z 0 cm 30 cm 80 cm 100 cm Observation w 130 cm D(w,C)

8 Ispra, 26/2/2008 8/21 SOIL Action Meeting, 04/03/2008 D*e Max depth D(x,A) D(y,B) D(z,C) 0 cm 20 cm 60 cm 120 cm A B C Centroid Utilitarian distance Calculation of distances x x y z 0 cm 30 cm 80 cm 100 cm Observation w 130 cm D(w,C) D(x,B) D(y,C) D(w,?) + +

9 Ispra, 26/2/2008 9/21 SOIL Action Meeting, 04/03/2008 D(x,A) D(y,B) D(z,C) 0 cm 20 cm 60 cm 120 cm A B C Centroid Joint distance D(w,C) x y z 0 cm 30 cm 80 cm 100 cm Observation w 130 cm Calculation of distances scaled depths x y z w A B C No scaled depths + +D(y,C) D(x,B) D*e Max depth

10 Ispra, 26/2/ /21 SOIL Action Meeting, 04/03/2008 The classification process Min. # Soil Type centroids Calculation of distances Calculation of new centroids D intra /D inter ratio Min+1. # Soil Type centroids Max. # Soil Type centroids Initialisation of cluster centroids Observation allocation Centroid readjustment Optimisation process optimization K-means techniques

11 Ispra, 26/2/ /21 SOIL Action Meeting, 04/03/2008 Observation allocation and centroid readjustment Distance table ABCD B ST A C B B 0.1 dmin Soil observations Distances to centroids Allocation process New centroid for B cluster = observation for which d intra B cluster minimal Centroid readjustment process Distance calculation iteration stopped when centroids ite n = centroids ite n-1

12 Ispra, 26/2/ /21 SOIL Action Meeting, 04/03/2008 OSACA interface ! Access at ! Enter the observation table If needed, enter the soil types table you want to use

13 Ispra, 26/2/ /21 SOIL Action Meeting, 04/03/2008 Enter the number of horizon classes Enter the number of soil classes you want

14 Ispra, 26/2/ /21 SOIL Action Meeting, 04/03/2008 Get the results (tables)

15 Ispra, 26/2/ /21 SOIL Action Meeting, 04/03/2008 OSACA Applications Soil taxonomy purpose Available Water Capacity prediction of soil profiles Focusing on The number of classes (level of taxonomic detail) The classes robustness (sensitivity of the distances) OSACA has been used for testing Look at: Carré & Jacobson, Numerical classification of soil profile data using distance metrics. Geoderma (available on line)


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