Nautical Map Research Articles

In Search of Prester John and the ‘River of Gold’. Mecià de Viladestes’ Map and Late Medieval Knowledge about Africa

Abstract Mecià de Viladestes’ nautical map provides many-faceted incentives to travel down the African west coast, emphasising especially Africa’s riches in gold and the presence of a Christian ruler known as Prester John. Understanding maps not as a conclusive result of the collection of knowledge but as a means of communication, this article aims to explore the relations between contemporary Latin European conceptions about Africa, its representations on maps and their probable argumentative objectives. From Latin-African contacts the idea had arisen to form an alliance to fight the Muslims, attacking from two directions. The representation of sub-Saharan Africa on Mecià’s map can be interpreted as taking up this discussion to argue for further exploration of Africa down its Atlantic coast, which might have influenced future decision makers such as Henry the Navigator.

The work of mapping and the mapping of work: prosumer roles in crowdsourced maps

ABSTRACTThis paper presents an analysis of crowdsourcing work with a particular focus on exploring what forces and characteristics of the collaboration practices and technologies encourage and discourage prosumer work behaviours. Data were gathered through depth interviews with prosumers of a crowdsourced digital nautical map, observational netnographic research of prosumers on angling forums, and interviews and meetings with the map providers. Incorporating research on consumer work and prosumption, three distinct prosumer roles are identified based on how angling prosumers differentially produce and consume the crowdsourced maps. These roles show multiple behaviours along the prosumption continuum, and in so doing extend the continuum by introducing a second dimension – work as private versus public prosumer activity. It concludes by offering suggestions for marketers to engage with prosumers in crowdsourcing contexts.

MBES-CARIS Data Validation for Bathymetric Mapping of Shallow Water in the Kingdom of Bahrain on the Arabian Gulf

Sound navigating and ranging (SONAR) detection systems can provide valuable information for navigation and security, especially in shallow coastal areas. The last few years have seen an important increase in the volume of bathymetric data produced by Multi-Beam Echo-sounder Systems (MBES). Recently, the General Bathymetric Chart of the Oceans (GEBCO) released these MBES dataset preprocessed and processed with Computer Aided Resource Information System (CARIS) for public domain use. For the first time, this research focuses on the validation of these released MBES-CARIS dataset performance and robustness for bathymetric mapping of shallow water at the regional scale in the Kingdom of Bahrain (Arabian Gulf). The data were imported, converted and processed in a GIS environment. Only area that covers the Bahrain national water boundary was extracted, avoiding the land surfaces. As the released dataset were stored in a node-grid points uniformly spaced with approximately 923 m and 834 m in north and west directions, respectively, simple kriging was used for densification and bathymetric continuous surface map derivation with a 30 by 30 m pixel size. In addition to dataset cross-validation, 1200 bathymetric points representing different water depths between 0 and −30 m were selected randomly and extracted from a medium scale (1:100,000) nautical map, and they were used for validation purposes. The cross-validation results showed that the modeled semi-variogram was adjusted appropriately assuring satisfactory results. Moreover, the validation results by reference to the nautical map showed that when we consider the total validation points with different water depths, linear statistical regression analysis at a 95% confidence level (p < 0.05) provide a good coefficient of correlation (R2 = 0.95), a good index of agreement (D = 0.82), and a root mean square error (RMSE) of 1.34 m. However, when we consider only the validation points (~800) with depth lower than −10 m, both R2 and D decreased to 0.79 and 0.52, respectively, while the RMSE increased to 1.92 m. Otherwise, when we consider exclusively shallow water points (~400) with a depth higher than −10 m, the results showed a very significant R2 (0.97), a good D (0.84) and a low RMSE (0.51 m). Certainly, the released MBES-CARIS data are more appropriate for shallow water bathymetric mapping. However, for the relatively deeper areas the obtained results are relatively less accurate because probably the MBSE did not cover the bottom in several deeper pockmarks as the rapid change in depth. Possibly the steep slopes and the rough seafloor affect the integrity of the acquired raw data. Moreover, the interpolation of the missed areas’ values between MBSE acquisition data points may not reflect the true depths of these areas. It is possible also that the nautical map used for validation was not established with a good accuracy in the deeper regions.

Spatial Pattern of Bathymetry in Wangi-Wangi Island and Its Surrounding Based on GEBCO Data and Nautical Map

The study aims is to define bathymetry based on General Bathymetric Chart of the Oceans (GEBCO) and Nautical Map using GIS technique. The methods used in this study are the kriging method which combines the spatial correlation among the data using GIS and Remote Sensing software. The result shows that bathymetry at research area can be divided into five classes, these are: (1) 0-2 meter with area of 1.797,61 hectare, (2) 2-5 meter with area of 2.059,06 hectare, (3) 5-10 meter with area of 1.184,02 hectare, (4) 10-25 meter with area of 3.025.00 hectare, (5) 25-200 meter with area of 5.648.62 hectare.The spatial pattern of bathymetry dispersed from the shallow water at the edge of beach and more deep at the offshore, except at the eastern side of Wangi-Wangi island which has barrier reef and created basin between them.

Key Technology in a Lightweight WPF-Based Electronic Map Engine

This paper introduces key technology in design and development of a lightweight WPF-Based electronic map engine, systematically analyzes characteristics of WPF technology, designs the structure of electronic map engine components, elaborates on data organization and management, vector and raster spatial data indexing method, presents a electronic map engine specific for nautical map display style.

Meeting Peak Load Demand by an Offshore Wind Farm in Brazil

The Itamaracá island close to the state of Pernambuco in Brazil receives thousands of visitors during the period of long summer vacations (3 months), increasing the peak demand by a factor of almost 200%. The purpose of this work is to demonstrate that the offshore wind turbines can meet peak energy demand and at the same time reduce impact on conventional energy generation during other months as well. The method involves a nautical wind map at a height of 10 m, and extrapolating it for the desired height by logarithmic law. The annual wind energy output employs Weibull probability density function. The wind turbine siting is chosen with the aid of the nautical chart. The results obtained demonstrate that three wind turbines would generate about 30,000 MWh per year, sufficient for meeting electricity demand in the island.

Fosfatização de solos e evolução da paisagem no arquipélago de Abrolhos, BA

A atividade da avifauna nos ecossistemas terrestres imprime profundas alterações químicas e mineralógicas nos substratos minerais. O objetivo do presente trabalho é investigar os impactos da atividade da avifauna na evolução da paisagem do arquipélago de Abrolhos através do estudo da distribuição espacial dos solos e suas características químicas, com ênfase na fosfatização. Foram estudados dez perfis de solos representativos das principais unidades de paisagem do arquipélago. Com base em observação de campo e interpretação de carta náutica da Marinha do Brasil (n. 1311), em escala 1:100.000, foi produzido o mapa de solos das ilhas. A presença generalizada de solos fortemente ornitogênicos, em áreas sem nidificação atual ou com fraca nidificação, indica uma ocupação pretérita por aves bem mais ampla que a atual. Alguns solos estudados em Abrolhos são de difícil classificação e refletem influência marcante da avifauna, atual ou pretérita.