*3.1.1 Remote sensing sensors terrain swath coverage estimation in disaster events (RSTSC*e*)*

The remote sensing satellites on orbit operation have the capacity to change the view pointing angle of their sensors through the roll maneuvers; operational strategy implemented with the aim to allow the sensors to observe in different positions in direction to the vertical trajectory view angle on the terrain; from the nadir angle,

until some degrees above this angle. In consequence, by mean of this operational characteristic, the remote sensing satellites have the ability to change their coverage on the terrain, which allows the sensors to cover a greater terrain extension in each satellite pass, through the different pointing angles. Principally, the pointing angles variation of the remote sensors view on orbit from nadir, achieved through the roll maneuver, is useful in disasters management to scan from two different view angles identical areas involved in disaster events, with the aim to obtain images in different perspectives of the areas affected by disasters. Also it is useful to images analysis in a three dimensional model for the best understanding of damages in disasters; in the same way, the sensors pointing angle change is effective to accomplish the mapping and interpretation of the zones affected by disasters with the purpose to create simulations model for damages to facilitate the emergency response task and recovery.

For this reason, a proposal based on a methodology following a reliable operational procedure to manage the remote sensing sensors terrain swath coverage estimation (*RSTSC*e) in emergency or hazard events is formulated. Accordingly, first, a procedure to determine the remote sensing sensors terrain swath coverage estimation (*RSTSC*e), minimum in nadir pointing angle and maximum off-nadir pointing angle is established, considering the remote sensing sensors field of view (FOV) specifications for this estimation as a reference. Subsequently, the remote sensing sensor potential terrain swath coverage in nadir angle and off-nadir angle (RSTSCp) using the spherical trigonometry mathematical method considering the law of sines for this aim is determined. In this sense, Eq. (1) specified below is proposed to calculate the remote sensing sensors terrain swath coverage estimated (LSCs) minimum in nadir pointing angle and maximum off-nadir pointing angle in emergency response.

$$RSTSC\_t = \mathcal{Z} \cdot \mathcal{S}\_r \cdot \text{(tan }FOV\_t\text{)}\tag{1}$$

**193**

**Figure 4.**

*angle and off-nadir angle (RSTSC* p*).*

*Emergency Communications Network for Disaster Management*

*3.1.2 Remote sensing sensors potential terrain swath coverage in disaster* 

operational abilities to re-pointing the cameras in direction to the vertical trajectory of the view angle on the terrain from the nadir, can reach a wide swath coverage on the terrain. Operational capacity is useful to plan and develop diverse remote sensing satellite missions in disasters, with the aim to cover one or more specific terrain extensions affected during disasters in less time through different cameras view angles' characteristic that allows providing quick response in disasters events.

In emergency scenarios, the remote sensing sensors potential terrain swath coverage estimation, in nadir angle and off-nadir angle (RSTSCp), as an operational procedure implemented on the satellite platform through the roll maneuvers, is an effective and reliable operational strategy to forecast in diverse disaster events, the expected terrain swath width to be scanned with the remote sensing sensors in the future satellite passes, using different view angles of the sensors over the terrain or areas that will be covered in a planned mission. In consequence, it is an important strategy in the disaster management, because it makes possible the prediction and planning in advance the terrain extensions affected by the occurrence of disasters that possibly will be explored by the satellite sensors. Fundamentally, three mathematical approaches can be used to calculate the remote sensing sensor potential terrain swath coverage in nadir angle and off-nadir angle (RSTSCp). These mathematical formulations or methods are the next: oblique spherical triangle method, the spherical method using intersecting lines, and the planar surface projection method [5]. In specific, the oblique spherical triangle method based on the earth model illustrated in **Figure 4** is the method selected to predict the remote sensing sensor potential terrain swath coverage in nadir angle and off-nadir angle (RSTSCp), because it is the most reliable and accurate method to perform

The oblique spherical triangle method previously mentioned and selected to predict the remote sensing sensor potential terrain swath coverage in nadir angle and off-nadir angle (RSTSCp) is taken into account; It is specified that this methodology is based on a mathematical approach or solution by which is projected a straight line from the remote sensing satellite on-orbit operation until a perpendicular plane

*Oblique spherical triangle method to predict the remote sensing sensor potential terrain swath coverage in nadir* 

*DOI: http://dx.doi.org/10.5772/intechopen.85872*

the aforementioned operational calculation.

*events (RSTSC*p*)*

where *RSTSC*e is the remote sensing sensors terrain swath coverage estimation; *Sr* is the satellite ranging or altitude; *tan* tangent; and *FOVs* is the sensor field of view angle.

For instance, to demonstrate the application of Eq. (1), the computation to estimate the terrain swath coverage (*RSTSC*e) minimum in nadir pointing angle, and the terrain swath coverage (*RSTSC*e) at maximum off-nadir pointing angle for the PAN and multispectral camera (PMC) of the Remote Sensing Satellite-1, as well as to the high-resolution camera (HRC) of the Remote Sensing Satellite-2, is executed; in this case, for both remote sensing satellites, an average ranging or altitude onorbit operation around 640 km is considered. In **Table 2**, the results obtained once the corresponding calculations have been done are specified.

It is notable, through the results obtained and specified in **Table 2** using Eq. (1), that the Remote Sensing Satellite-1 and Remote Sensing Satellite-2, using their


**Table 2.**

*Remote Sensing Satellite-1 and Remote Sensing Satellite-2 cameras terrain swath coverage estimation.*

*Emergency Communications Network for Disaster Management DOI: http://dx.doi.org/10.5772/intechopen.85872*

*Natural Hazards - Risk, Exposure, Response, and Resilience*

until some degrees above this angle. In consequence, by mean of this operational characteristic, the remote sensing satellites have the ability to change their coverage on the terrain, which allows the sensors to cover a greater terrain extension in each satellite pass, through the different pointing angles. Principally, the pointing angles variation of the remote sensors view on orbit from nadir, achieved through the roll maneuver, is useful in disasters management to scan from two different view angles identical areas involved in disaster events, with the aim to obtain images in different perspectives of the areas affected by disasters. Also it is useful to images analysis in a three dimensional model for the best understanding of damages in disasters; in the same way, the sensors pointing angle change is effective to accomplish the mapping and interpretation of the zones affected by disasters with the purpose to create simulations model for damages to facilitate the emergency response task and recovery. For this reason, a proposal based on a methodology following a reliable operational procedure to manage the remote sensing sensors terrain swath coverage estimation (*RSTSC*e) in emergency or hazard events is formulated. Accordingly, first, a procedure to determine the remote sensing sensors terrain swath coverage estimation (*RSTSC*e), minimum in nadir pointing angle and maximum off-nadir pointing angle is established, considering the remote sensing sensors field of view (FOV) specifications for this estimation as a reference. Subsequently, the remote sensing sensor potential terrain swath coverage in nadir angle and off-nadir angle (RSTSCp) using the spherical trigonometry mathematical method considering the law of sines for this aim is determined. In this sense, Eq. (1) specified below is proposed to calculate the remote sensing sensors terrain swath coverage estimated (LSCs) minimum in nadir pointing angle and maximum off-nadir pointing angle in emergency response.

*RSTSCe* = 2 ∙ *Sr* ∙ (*tan FOVs*) (1)

where *RSTSC*e is the remote sensing sensors terrain swath coverage estimation;

For instance, to demonstrate the application of Eq. (1), the computation to estimate the terrain swath coverage (*RSTSC*e) minimum in nadir pointing angle, and the terrain swath coverage (*RSTSC*e) at maximum off-nadir pointing angle for the PAN and multispectral camera (PMC) of the Remote Sensing Satellite-1, as well as to the high-resolution camera (HRC) of the Remote Sensing Satellite-2, is executed; in this case, for both remote sensing satellites, an average ranging or altitude onorbit operation around 640 km is considered. In **Table 2**, the results obtained once

It is notable, through the results obtained and specified in **Table 2** using Eq. (1),

**Camera FOV max-off nadir angle**

PMC 5.15° 31° 115.328 km 768 km

HRC 2.93° 29° 65.51 km 709 km

that the Remote Sensing Satellite-1 and Remote Sensing Satellite-2, using their

*Remote Sensing Satellite-1 and Remote Sensing Satellite-2 cameras terrain swath coverage estimation.*

is the sensor field of view

**RSTSCe in nadir angle**

**RSTSCe max-off nadir angle**

*Sr* is the satellite ranging or altitude; *tan* tangent; and *FOVs*

the corresponding calculations have been done are specified.

**Camera FOV in nadir angle**

**Satellite camera**

**192**

**Table 2.**

angle.

**Satellite platform**

Remote Sensing Satellite-1

Remote Sensing Satellite-2 operational abilities to re-pointing the cameras in direction to the vertical trajectory of the view angle on the terrain from the nadir, can reach a wide swath coverage on the terrain. Operational capacity is useful to plan and develop diverse remote sensing satellite missions in disasters, with the aim to cover one or more specific terrain extensions affected during disasters in less time through different cameras view angles' characteristic that allows providing quick response in disasters events.
