Software for the geometric characterisation of insect-proof screens.

摘要

Novel software has been developed for the geometric characterisation of agrotextiles intended for installation in greenhouse vents as a means of crop protection. This characterisation of insect-proof screens is essential with a view to keeping insects out and also from an aerodynamic point of view. The method of analysis is based on digital images taken by microscope or scanner. The geometric procedure considers that each hole of the screen represents a quadrilateral, as it is defined by four threads of monofilament that cross over each other. The software developed using Visual Basic allows us to identify the coordinates of the vertices of the quadrilaterals and therefore to carry out a complete characterisation of the agrotextiles: number of threads per unit length, porosity of the sample, dimensions of the holes, thickness of the threads, area of the holes and the largest circle contained in the holes. The analysis of the data provided by the software allows us to study the uniformity of the material and also to detect flaws in its manufacture. The software includes a pattern for identifying the vertices with a high percentage of accuracy. For instance, it analysed over 40,000 vertices with only 1.14% error, mostly due to dirt on the screen. The software developed includes procedures to detect these errors, to alert the user to the type of error and to correct them. There is no other specific procedure to measure the characteristic dimensions of insect-proof screens and, therefore, it is no possible to contrast in this way the results that are obtained with the proposed method. Consequently, the measurement method has been verified using a set of screens of known dimensions manufactured for this very purpose. The results obtained are excellent, revealing that the differences between the expected values and the measured ones are well below the sensitivity of the device used to obtain the digital images.Digital Object Identifier http://dx.doi.org/10.1016/j.compag.2012.01.001