PlantToon - drawing and pruning fruit trees

Computer 3D drawing is a task that is performed in a number of different ways as it is attested by the number of software tools designed to capture the geometry of real world objects. One major problem of 3D application programs is the time the user requires to become familiar with the environment and learn basic capabilities, which can range from a few days to months: these difficulties increase further when dealing with a complicated geometry as that of a tree. Most of time is required to develop a 3D perception in a 2D environment (the PC console). PlantToon was developed from previous experience on software born for editing and navigating plants scanned with a digitizing-arm (Magnanini e al., 1998). The present version allows to import a digitized tree, but its main objective is to teach pruning techniques, so it allows for drawing a plant from scratch and then lets the user cut and remove branches, realistically. Expert pruners were consulted during the development of PlantToon and their suggestions were used to build a plant-drawing oriented 3D-CAD tool with particular innovations that allows the ability to draw a plant quickly. PlantToon uses a single canvas for the 3D structure of the plant, and a new technique for navigation. A tool palette allows the user to add, delete, move, and select objects such as the trunk, primary and secondary branches, shoots, twigs, suckers, etc. and more objects are added gradually according to a hierarchical organization. The topological structure, together with 3D graphics is easy to navigate, allowing a user to adjust pruning to information such as age, number of buds or fruit load. The 3D rendering offers the users-view to move as in the field. PlantToon also allows to operate stereoscopically using the anaglyph technique so as to give the pruner the opportunity to “get inside the scene” using common blue-red spectacles. PlantToon was developed to draw fruit trees as in their dormant state. Foliage is not considered in the present version, both because of the problems leaves make for reading branch structure, and because pruning usually is performed in the period with no foliage. In the future we plan to develop methods for exporting PlantToon drawings in formats allowing to exchange a virtual tree via the Internet or with a growth simulation engine, and to record details on branches and fruits. PlantToon has been written in VB6 (under MS-Windows) and is available as a demo from the author.