The core of the procedure resides in the algorithm for automatically segmenting the filtered images in such a way that relative differences in canopy vigor were objectively quantified. The versatility of the system was further enhanced by implementing two sampling levels: intensive coverage of 1 m2 and super-intensive for 0.1 m2. This monocular camera was able to sense in the visible, NIR, and UV spectra, selectively isolated with bandpass filters. This research develops a new methodology to generate globally-referenced vigor maps in vineyards from ground images taken with a camera mounted on a conventional tractor. While advantageous because they cover large areas and provide diverse radiometric data, they are unreachable to most of medium-size Spanish growers who cannot afford such image sourcing. The geographic information required to implement precision viticulture applications in real fields has led to the extensive use of remote sensing and airborne imagery. In the final discussion, some thoughts on future archaeological aerial research are given. Besides a theoretical underpinning, real-world examples will assess the potential of this new approach in detection of vegetation marks and prove that this low-cost, multispectral method might be beneficial in identifying and enhancing weak crop stresses that are lost when taking only the broad visible spectrum into account. The latter two bands are used in the calculation of a R700/R800 vegetation index. The new approach consists of three simultaneously operated digital still cameras, each of them capturing information in a different spectral waveband: the visible, near-infrared and red-edge spectral region. Instead of basing archaeological interpretation on only direct visual inspection of the conventionally acquired colour photographs, this contribution briefly reviews the reflectance properties of plants and uses them to present a new low-cost imaging technique beneficial for the detection of (faint) archaeologically induced vegetation marks. Aerial archaeologists flying in small aeroplanes have only partially exploited this knowledge. This fundamental understanding has facilitated the development of various non-destructive sensing methods for detecting vegetation stresses, monitoring plant growth and calculating crop yield. Scientists from different research disciplines have provided essential information that relates the biophysical characteristics of plants to their spectral reflectance. By presenting the very first aerial and archaeological digital NUV frames, the weaknesses and/or advantages over conventional visible imaging may be evident – notwithstanding the infancy of this approach. The use of a remotely controlled platform will be shown to be indispensable as the inevitable long shutter speed compels the use of such a very stable, unmanned aerial device. Although it is far from certain that this technique could enhance, let alone reveal new archaeologically related anomalies, this paper discusses the practicalities of digital NUV imaging: from the modification of digital still cameras (DSCs) and the choice of appropriate optics over the extremely important NUV interference filters to the focus and exposure compensation needed. Consequently, this waveband of the EM spectrum is rarely employed in aerial photography and its reflected portion only acquired in very specific applications.Archaeological aerial NUV imaging can thus truly be seen as a completely unexplored research field. Additionally, sensors acquiring this part of the UV wavelengths must be operated from low altitudes to minimize the effects of strong Rayleigh scattering to which the NUV radiation is subjected. However, the largest portion of this emitted energy is blocked by the ozone layer of the atmosphere, only allowing the near-ultraviolet or NUV (comprising the spectral band between 315 nm and 400 nm) to reach the earth's surface. Even though the sun has its peak emission of electromagnetic (EM) radiation in the visible waveband, it still produces a substantial amount of ultraviolet (UV) wavelengths (10–400 nm).
0 Comments
Leave a Reply. |