Continuous Visible Query for Three-Dimensional Objects in Spatial Databases

<table class="figure-group"><tr class="fig-image" id="a"><td><object data="https://static-preview.hindawi.com/articles/mpe/volume-2016/6340856/figures/6340856.fig.005a.svgz" name="6340856.fig.005a" type="image/svg+xml"></object></td></tr><tr class="fig-caption"><td><b>(a) </b>Calculation of the projection angle</td></tr><tr class="fig-image" id="b"><td><object data="https://static-preview.hindawi.com/articles/mpe/volume-2016/6340856/figures/6340856.fig.005b.svgz" name="6340856.fig.005b" type="image/svg+xml"></object></td></tr><tr class="fig-caption"><td><b>(b) </b>Distance between query point and different points in projection of object</td></tr></table>

<div>Change of distance and projection angle.</div>

Mathematical Problems in Engineering

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Figure 5

Figure 5: Continuous Visible Query for Three-Dimensional Objects in Spatial Databases 