3D plant architecture

3D Plant Architecture Acquisition

Introduction

Plant architecture describes the connection between its components (ramification: topology) also component space distribution (position, orientation, dimension and form: geometry concepts) In plant ecophysiology, the plant architecture measurements are used in plant ? building, to verify growth simulation models, or study some functioning aspects. The 3D digitising consists in spatial co-ordinate measurement by help of a pointer an operator sets on the plant. Though needing a high manual application, the 3D digitising is nowadays a reference method for describing plant structure: all components can be measured, and 3D data acquisition can be combined with other different measurement types, used to describe digitised points, especially the botanical component nature and their position in plant topology.

Principle

The digitising method which has been developed at PIAF uses magnetic technology equipment FASTRAK 3SPACE POLHEMUS. The system is made up of a transmitter which generates orthogonal magnetic fields, a sensor placed on the point which is to measure, and a central unit; The sensor has magnetic coils, in which flows are induced at the moment the sensor is placed in the volume in which magnetic fields are active. The induced flow value is related to the spatial location and orientation of the sensor. The magnetic digitiser is sensitive to the presence of metallic objects in the measurement volume. On the other side, the magnetic technology is the only one capable of simultaneous measurement of spatial co-ordinates and surface orientation, in the same time. It is also insensitive to meteorological (atmospheric) conditions and to the presence of (non metallic) objects between the transmitter and the sensor .

Software

PIAF has developed software for 3D digitising data acquisition for tree architecture :

• POL95 drives the magnetic digitiser; it permits digitiser configuration, and data capture in spreadsheet format for measured points.

• 3A (Tree Architecture Acquisition) drives the plant topology acquisition according to standard coding AMAPmod. It allows to configure the way of plant architecture descriptions using (choice of the plant entities, topology rules), topology acquisition by the defined rules, plant component positioning by using a magnetic 3D digitiser, and real time visualising of the measured plant.

 3A software: Acquisition of tree Architecture

 PiafDigit software

Applications

Digitising has been mainly used to discribe branch systems and foliage spatial distributin. Anyway, virtual plant images obtained by 3D digitising are very like real plant photographs.

Branch system description can be analysed with AMAPmod software, in order to deduce behaviour laws, meanwhile foliage distribution measuring allows to infer light interception characteristics, for instance with VegeSTAR software.

Images 

 Photograph and virtual image of a 20 year old walnut tree

Virtual image of a digitised oaks root system

Photograph and virtual image of a white clover canopy

 Peach tree digitising and foliage reconstruction with VegeSTAR

Tél  : +33 4 43 76 14 12 Fax : +33 4 43 76 14 10 Nicolas.Dones@inrae.fr

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