14. starptautiskā konference 2012 - Latvijas Jūras akadēmija

Proceedings of 14th International conference „Maritime Transport and Infrastructure - 2012”consistent ice packs located? (2) Where is the shell ice, lightercompounded ice located? (3) Where arethe crevasses accessible for navigation and, ultimately: most optimal course of voyage for getting intothe ice-free waters with minimal efforts and related risks?The basis of this method is deployment of UVA on short notice, as well as to get protractedvisual image of ice situation around the ship, compared with this view from bridge. Once this methodis used, command and control of UAV is being conducted by means of ‘’direct control”, or control bythe method of pre-planned waypoints. In particular situations, when ice-fields have to be crossedwithin restricted geographical areas, the ‘’direct control ‘’ of UAV is better suited, because it is moresimplistic and enables fast camera’s switching from ‘’perspective’’ to ‘’detailed’’ mode of view andobservation. The mode of ‘’perspective observation’’ is being executed on the certain altitude of flight,where the water space is being best visually embraced from, thus delivering better qualitycomprehension about ice conditions in surroundings. Altitude of flight is also constrained by cloudbase height and air visibility.In order to execute the surveillance pattern by method of Perspective surveillance (Fig.2),UAV is being raised up to definite altitude H, with further surveillance route in transversal plane togeneral course CoG. The flight is being executed within the range of ‘’direct control’’ from the ship,which is located at point O. First surveillance route dc delivers the factual visual data and informationwithin defined water zone ABCD. In case if acquired data do not provide sufficient information foroptimal route selection, then flight is being switch over to automated mode, when UAV proceedsbetween pre-planned waypoints. The automated mode’s waypoints should be designated consideringthe transverse ‘’sweep range’’ from initial surveillance track dc, in order to prevent surveillance gapsand blank spots. It means that for the sake of reliable data from two adjacent flying surveillance tracks,there should be 20-30% coverage overlap.Upon the initial visual screening, once preliminary data and information has been acquiredabout crevasses in ice-fields, ice thickness, ice concentration and availability of ice-free water space, aseafarer comes to a decision on further surveillance: if deemed necessary to get more detailed visualdata from certain areas.Fig. 2. The method of perspective surveillanceAdditional surveillance is being conducted by the method of ‘’Detailed Surveillance’’, whenthe flight is being executed on the low altitude with the main purpose to rectify ice conditions insurroundings and to eliminate doubts about most optimal ship’s course selection. DetailedSurveillance utilizes such the camera’s generous features like in-zooming of an object and/orobserving a particular object from different angles of view.In the process of Detailed Surveillance ice crevasses and ice-openings are being surveyed,with the aim to clarify their sizing and dimensions.60