Flight Planning for Arial Photography: Initial Data, Flight Characteristics ′ Calculation, Distance between Strips (Especially for GATE-Geospatial 2022)

Glide to success with Doorsteptutor material for CBSE/Class-8 : get questions, notes, tests, video lectures and more- for all subjects of CBSE/Class-8.

Examrace Books on Mapping, GIS, and Remote Sensing prepares you throughly for a wide range of practical applications.

  • The planning of a photogrammetric project can be divided into three phases:
    • Flight planning that has to be followed to take all the aerial photos that will be used in the project.
    • Terrestrial control planning, as well as the execution of all surveying tasks that satisfy the accuracy required by the project.
    • Estimated costs associated with the project.
  • The main condition in the whole flight planning is obtaining an appropriate photographic coverage with a minimum of photographs, in a way that each part of the field, however small it may be, should be stereoscopically covered.
  • In other words, the entire surface should be covered in overlapping areas, both contiguous photographs of a flight path and overlapping areas of neighbour flight paths.
Flight Project of a Linear Layouts

As can be seen in the above figure, in the case of civil linear works, the geometry of a linear layout can complicate the capture of a photogram in terms of all areas having stereoscopic overlap.

Initial Data

  • The available initial data are the geometry of the area that is going to be overflown, and the scale of the cartography we want to make.
  • From this data, we should plan the flight by calculating the number of necessary photographs and their disposition so that the entire desired surface can be resituated.

Flight Characteristics՚ Calculation

  • Some of the premises mentioned in previous chapters will be reminded.
  • Firstly, the scale of the final product should be considered to know which scale should be used to measure the ground when taking the photogram.
Relation between Photographic and Cartographic
  • The second datum that must be obtained is the height of the flight, which is linked to the camera՚s focal length.
  • We cannot choose this datum, but we must adapt ourselves to the cameras of the company in charge of the photogrammetric flight.
  • Once this datum is known, we can obtain the flight՚s height over the ground.

Relation between the scale and the flight՚s Height

Flights Height Above Sea Level

According to the end lap and side lap that have been stated in the technical specifications, S1 and S2 dimensions of the stereoscopic models will be obtained as well as their overlap between strips.

Photographs Dimensions

Photogram՚s Size on the field

The distance travelled by plane between photographs is known as “Base” and is obtained as follows:

Base

Side lap refers to the distance between strips and is determined by the following parameters:

Side Lap Refers

Distance between Strips

If the working area is regular or if it may resemble a regular polygon, like the one in then, the strips would be parallel.

Flight Scheme in a Regular Area
  • Notwithstanding, if the area of the project has an irregular shape, or if it is long, narrow and not aligned with cardinal directions as the one in below figure (riverbeds, layouts of new roads, coastlines, etc.) it is uneconomic to fly in North-South or East-West directions because the strips obtained would have few useful photograms.
  • In this case, it is evident that we should fly parallel to lines of major longitudes, but being careful to cover the strips changes sufficiently.
Flight Scheme in a Irregular Area

Calculating Total Number of Photographs

Now, the number of photographs needed to cover the whole area will be calculated in detail, following figure geometry.

Photograms Disposition to Calculate the Total Number

The Number of Photographs in each strip “” is

Number of Photographs in each strip

The Number of Strips “” is

Number of Strips

Finally, the total number of Photographs is:

Total number of Photographs

  • n volume needed to store all the photographs, the number of ground control and checkpoints in the field will depend on this number.
  • That is why it should not be overvalued nor undervalued because the real costs of the project can differ from the estimated costs due to the wrong planning.

Developed by: