4.8.8. Total number of photographs

The total number of photographs are obtained by multiplying the number of photographs in each strip by the number of flight lines) (e.g., 6x2= 12 photographs in Figure 4.7).

To find out the total number of photographs taken during an aerial survey, you operate with two key components: the number of photographs taken in each strip (the cross-section of area covered during a single pass of the aircraft) and the total number of flight lines (the routes taken by the aircraft to cover the entire area). So, if there are 6 photographs taken in each flight strip and there are 2 flight lines, the total is calculated as follows: 6 (photographs per strip) multiplied by 2 (number of strips) equals 12 photographs in total.

Think of it like painting a large mural on a wall. If you paint 6 sections of the mural on one trip across the wall (one flight strip) and then take a second trip in a different direction to paint another 6 sections, you would end up with a total of 12 sections painted on the wall.

Flight lines refer to the paths the aircraft takes as it captures images. Each flight line covers a specific area, and the number of flight lines directly affects the total number of photographs taken.

Flight lines are essentially the defined routes in the air that the aircraft follows to ensure complete coverage of the area being photographed. When planning a photogrammetric survey, it's crucial to determine how many flight lines are necessary to adequately cover the entire area. For instance, if the survey requires more coverage, additional flight lines will be necessary, which in turn will increase the total photograph count.

Consider a gardener who is planting seeds across a large field. If she walks in rows (flight lines) every few feet to ensure no patch of ground is left unplanted, the number of rows she walks will directly impact how many seeds she plants—just like flight lines impact how many photographs are captured.

The number of flight lines is determined based on the coverage needed for the project's specific area size and characteristics.

When establishing flight lines, planners must consider the size of the area being surveyed and the required overlap between photos for accurate results. Larger areas may require more flight lines to ensure there are no gaps in the data, and specific terrain features may also impact where and how flight lines are created. This relationship is fundamental because effective aerial photography relies on comprehensive coverage for precise mapping.

Imagine you are taking a class photo of a large group. If you stand too far away, some people may be cut out of the picture. To avoid this, you need to adjust your position (flight line) based on how many people are in the photo (area size) and whether everyone needs to be in the frame (overlap).

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