The formula to calculate the Ground Sample Distance (GSD) is:
\[ GSD = \frac{A \times SH}{FL \times IH} \]
Where:
GSD, short for ground sample distance, is a metric used with drone mapping and surveying to relate the focal length, resolution, and camera distance from the object. Knowing all but one of any of the variables present in the formula above means a person can solve for the missing variable. The units for GSD are distance per pixel, i.e. cm/pixel.
Let's say the altitude (A) is 100 meters, the sensor width/height (SH) is 36 mm, the focal length (FL) is 50 mm, and the image width/length (IH) is 4000 pixels. Using the formula:
\[ GSD = \frac{100 \times 36}{50 \times 4000} \approx 0.018 \]
So, the ground sample distance (GSD) is approximately 0.018 cm/pixel.
Definition: Calculates the ground sampling distance (GSD) based on sensor parameters and flight altitude.
Formula: \( GSD = \frac{S \times H}{F} \)
Example: \( GSD = \frac{0.005 \times 100}{50} \)
Definition: Calculates the ground distance between two points based on their coordinates.
Formula: \( D = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2} \)
Example: \( D = \sqrt{(10 - 4)^2 + (8 - 2)^2} \)
Definition: Calculates the average ground sampling distance over a given area.
Formula: \( \text{Average GSD} = \frac{\sum GSD_i}{n} \)
Example: \( \text{Average GSD} = \frac{0.1 + 0.2 + 0.15}{3} \)
Definition: Converts map distance to actual ground distance.
Formula: \( \text{Ground Distance} = \text{Map Distance} \times \text{Scale Factor} \)
Example: \( \text{Ground Distance} = 5 \times 1000 \)
