Abstract
Abstract. The ability to repeat analyses on the same very small area of a surface is crucial to obtain reliable comparative data. For example, in a painting the boundary between two different, small painted areas can be very blurred; if an analyst needs to track over the time a specific and tiny pigment spot (e.g., to assess the reliability of a conservation treatment), manual positioning of the analyser can lead to a mismatch that might undermine any data comparison. The use of automatic positioning systems can improve the ability to hit the right spot, so to collect reliable data. This work focuses on the development of an open hardware XYZ system based on 3D printers’ architecture and equipped with an imaging system. It demonstrates that the combination of image processing methods with the G-code generated during the movements of the XY axes can allows to avoid misalignment of the object that needs to be analysed, and thus to improve measurements’ spatial precision. The XYZ positioning system and the positioning calibration method are now tested on Modernist hydraulic tiles from Barcelona (Catalunya, Spain), a decorative and functional element in danger because of the estate speculation that is affecting the architectonic identity of the Catalan capital.
Highlights
The ability to repeat analyses on the same very small area of a surface is crucial to obtain reliable comparative data
In a painting the boundary between two different, small painted areas can be very blurred; if an analyst needs to track over the time a specific and tiny pigment spot, manual positioning of the analyser can lead to a mismatch that might undermine any data comparison
These, along with the microcontroller unit (MCU) Raspberry Pi Zero, were mounted on a carrier that can be fixed on the head of the positioning system so that the center of the camera optic is equivalent to the center of the head of the positioning system (Figure 6)
Summary
The ability to repeat analyses on the same very small area of a surface is crucial to obtain reliable comparative data This is a critical point of any measurement campaign, even more when dealing with handheld analytical instrumentations. In the case of contact analyses, the area to be analysed is equal to the device slit; in the case of non-contact analysis that must be performed very close to the surface (e.g., 1-10 mm), the analysed area will slightly vary according to the distance between the detector and the surface In both cases, knowing the spatial coordinates of a point to be analysed is not always a simple task, and hitting the same area manually can be very tricky. In a painting the boundary between two different, small painted areas can be very blurred; if an analyst needs to track over the time a specific and tiny pigment spot (e.g., to assess the reliability of a conservation treatment), manual positioning of the analyser can lead to a mismatch that might undermine any data comparison
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