## 5 Camera Placement based on HybVOR Approach
### Deploying Camera Network  
After highlighting the importance of placing cameras on Voronoi edges in Section 5.1, the next step is to find the best position of each camera in order to achieve the maximum possible coverage while minimizing the number of cameras. To do so, the best location on the Voronoi edge will be defined based on three constraints: (1) Parameters of cameras, (2) the location of buildings and (3) minimizing the foreshortening effect. In this work, two assumptions are considered; the first one is that cameras should be installed on poles. This statement has been confirmed by the costal guard of Jeddah Seaport. The second assumption states that all cameras have the same following parameters (_c.f._ Section 3.1):  
* **OFFSETB = 0** (there is no artificial target on the field). * **AZIMUTH1 = 0\({}^{\circ}\)** (the starting horizontal angle). * **AZIMUTH2 = 360\({}^{\circ}\)** (the ending horizontal angle of the scan range). * **VERT1 = 90\({}^{\circ}\)** (the upper limit of the vertical angle). * **VERT2 = -90\({}^{\circ}\)** (the lower limit of the vertical angle). * **RADIUS1 = 0** (the starting distance from which a point may be visible). * **RADIUS2 = Constant** (the ending distance where any point beyond this distance will be surely not visible, this parameter represent the camera range). There are two other parameters of cameras that may take varying values, which are **SPOT** and **OFFSETETA**:  
* **SPOT** corresponds to the ground elevation where the camera will be placed. * **OFFSETETA** is related to the height of buildings to be monitored from each camera. In order to generate Voronoi diagrams, buildings' footprints are used as generator objects. These footprints may be produced either from an existing model of 3D buildings or form topographic surveys. Figure 8: Camera placement on the Voronoi edge for a better observability and coverage for roads. Once the Voronoi diagram is generated, each edge will be split from one of its two Voronoi vertices based on the camera range as follows:  
1. If the length of a Voronoi edge is less than the range of the camera, then this edge will not be divided. 2. If the length of a Voronoi edge is more than the range of the camera, then this edge will be divided into equal segments. The number of these new segments is calculated based on the following procedure: \[IF\ ((L_{VE})Mod\ (R_{cam})=0)\ Then\ Ns=Ceil\ \left(\frac{L_{VE}}{R_{cam}}\right)\] (4) \[\text{ELSE}\ ((L_{VE})Mod\ (R_{Cam})<>0)\ \text{Then\ Ns}=Ceil\ \left(\frac{L_{VE}}{R_{Cam}} \right)+1\] (5)  
where:  
**-**: **Ns**: is the number of new segments generated from splitting a Voronoi Edge. **-**: **Ceil**: is the mathematical function that calculates the integer part of a number (for example Ceil(1.45) = 1). **-**: **Mod**: is the mathematical function that calculates the remainder of a division. **-**: **L**ve**: is the original length of the Voronoi edge. **-**: **R**Cam**: is the range of the camera. Thereafter, the length of each new generated segments will be equal to:  
\[L_{SPVE}\ =\left(\frac{L_{VE}}{Ns}\right) \tag{6}\]  
where \(\mathbf{L_{SPVE}}\) is the length of each new segment that is produced form splitting the corresponding original Voronoi edge. Following the subdivision of a Voronoi edge into equal segments, a camera is placed at the midpoint of each new segment. The choice of placing cameras in such a way increases the observability of buildings. Indeed, if a camera is placed on a Voronoi Vertex, it may cause narrow angles to monitor buildings (and building entrances in particular), which is one of the main reasons behind the  
Figure 9: Placing Cameras on Voronoi edge. (**A**) Voronoi edge length is less than camera range, (**B**) Voronoi edge length is more than camera range. foreshortening problem. Figure 9 shows the placement of cameras in the middle of Voronoi segments with respect to the surrounding buildings (_c.f._ Section 5.1).