## 1 Introduction and Related Works
In particular, they do not have characteristic elements that are easily associated with the surrounding landscape in which they are installed, which could better integrate them with the landscape, further improving their quality impact. A further consideration comes from the Countryside Agency and Scottish Natural Heritage [13], which provides the following definition of landscape:  
\"Landscape [...] results from the way that different components of our environment--both natural (the influences of geology, soils, climate, flora and fauna) and cultural (the historical and current impact of land use, settlement, enclosure and other human interventions). People's perceptions turn land into the concept of landscape. This is not just about visual perception, or how we see the land, but also how we hear, smell and feel our surroundings, and the feelings, memories or associations that they evoke.\"  
From the previous statement, we can achieve two key-factors involved in the definition of landscape:  
- The \"cultural\" elements of a land/territory as landscape main factors, in addition to natural elements. - The \"perceptions\" of the landscape as a mix of sight as well as feelings (i.e., physical as well as psychological sensations). Therefore, the visual impact is also related to people's visual amenity, which is defined as: \"the overall pleasantness of the views they enjoy of their surroundings\" in Guidelines for Landscape and Visual Impact Assessment--Third Edition, 2013 (GLVIA3) [18]. Again, the GLVIA3 [18] states:  
\"An assessment of visual effects deals with the effects of change on views available to people and their visual amenity. The concern here is with assessing how the surroundings of individuals or groups of people may be specifically affected by changes in the content and character of views as a result of the change or loss of existing elements of the landscape and/or introduction of new elements.\"  
Within the mitigation measures to be implemented in the design of facilities, [19] includes the following requirement/guideline among the others:  
\"Where it is not practicable to screen or integrate a facility into the landscape, consider designing the facility to be a feature in the landscape, taking into consideration the form, texture and arrangement of buildings and structures.\"  
To sum up, the related literature review highlights the lack of recent methodological innovation capable of supporting the development of alternative design of pylons, with an enhanced visual quality. The current design method is based on the optimization of reticular structures (or trusses) made of galvanized steel [20; 21; 22; 23; 24], focusing on the reduction of the cost of material, transportation, erection, and maintenance. An interesting approach to topology in the pylon design is presented in [25]. With respect to the visual impact, all these approaches completely neglect the integration of the design process with methods for enhancing its quality, and the shape of pylons placed in very different areas does not present structural nor morphological differences between urban, agricultural or wild areas. Again, the literature review highlights two opposite point of views about visual impact. On the one hand, according to [PERSON] [7], the visual impact may be defined as \"any modification in landforms, water bodies, or vegetation, or any introduction of structures or other human-made visual elements, that negatively or positively affects the visual character or quality of a landscape through the introduction of visual contrasts in the basic elements of form, line, color, and texture\". On the other hand, the visual impact, depending on the subjective perception of the observer, could be improved thanks to harmonious elements with respect to the landscape, but also which bring to people's mind cultural, historical, naturalistic references, suggesting harmonious and not disruptive perceptions.