In surveying work, scale topographic maps such as 1:500,1:1000, 1:2000 are often heard. What is the relationship between these scales, ground resolution (spatial resolution), and flight height? Here I briefly summarize and share with you.
1. Scale accuracy
The main factor for determining the scale of a map is the size of the smallest ground object to be expressed on the map; The plane position of the point or the distance between two points must be accurate to what extent, so we need to know the scale accuracy, generally, the minimum distance between two points that human eyes can distinguish is 0.1. Therefore, the horizontal distance of the field represented by 0.1mm on the topographic map is called scale precision. According to the scale precision, you can not only determine the precise extent of the ground distance according to the scale, but also determine the scale of the measurement according to the specified precision of the measurement distance. For example, when mapping a 1:1000 scale topographic map, the accuracy of the above-ground distance is 0.1mm × 1000=0.1m. If the accuracy of 0.5m can be expressed in the map, the scale used for the survey is 0.1/0.5m = 1/5000. 1:10000, urban planning and design (overall urban planning, plant location, regional location, and program comparison), etc., 1:5000, as above; 1:20000 urban detailed planning and preliminary design of the Project 1:1000, urban detailed planning, management, underground civil air defense project completion drawing, construction plans design of the project, etc. 1:500 0.05 as above.
2. The relationship between scale and resolution
Scale 1:50000 representative 1 m on the map, representing the actual 50000 m. The conversion formula between meters and pixels is: dpi is the number of pixels per inch
1 inch = 0.0254 m = 96 pixels;
1 pixel = 0.0254/96=0.00026458 m
One pixel in the figure represents
0.00026458*50000=13.2291667 m.
Scale 1:50000 representative 1 m on the map, representing the actual 50000 m. The conversion formula between meters and pixels is: dpi is the number of pixels per inch
1 inch = 0.0254 m = 96 pixels;
1 pixel = 0.0254/96=0.00026458 m
One pixel in the figure represents
0.00026458*50000=13.2291667 m.
3. Relationship between flight height and ground resolution
1. Scale accuracy
The main factor for determining the scale of a map is the size of the smallest ground object to be expressed on the map; The plane position of the point or the distance between two points must be accurate to what extent, so we need to know the scale accuracy, generally, the minimum distance between two points that human eyes can distinguish is 0.1. Therefore, the horizontal distance of the field represented by 0.1mm on the topographic map is called scale precision. According to the scale precision, you can not only determine the precise extent of the ground distance according to the scale, but also determine the scale of the measurement according to the specified precision of the measurement distance. For example, when mapping a 1:1000 scale topographic map, the accuracy of the above-ground distance is 0.1mm × 1000=0.1m. If the accuracy of 0.5m can be expressed in the map, the scale used for the survey is 0.1/0.5m = 1/5000. 1:10000, urban planning and design (overall urban planning, plant location, regional location, and program comparison), etc., 1:5000, as above; 1:20000 urban detailed planning and preliminary design of the Project 1:1000, urban detailed planning, management, underground civil air defense project completion drawing, construction plans design of the project, etc. 1:500 0.05 as above.
2. The relationship between scale and resolution
Scale 1:50000 representative 1 m on the map, representing the actual 50000 m. The conversion formula between meters and pixels is: dpi is the number of pixels per inch
1 inch = 0.0254 m = 96 pixels;
1 pixel = 0.0254/96=0.00026458 m
One pixel in the figure represents
0.00026458*50000=13.2291667 m.
Scale 1:50000 representative 1 m on the map, representing the actual 50000 m. The conversion formula between meters and pixels is: dpi is the number of pixels per inch
1 inch = 0.0254 m = 96 pixels;
1 pixel = 0.0254/96=0.00026458 m
One pixel in the figure represents
0.00026458*50000=13.2291667 m.
3. Relationship between flight height and ground resolution
If the photosensitive element is 1 inch, it is 12.8*9.6, the length of Boom Shot is 8mm, and the maximum resolution is 5472 × 3078, the pixel size is 2.7um. If the GSD of the photo to be shot is 5cm, the altitude is 148m.
4 Photosensitive element size schematic diagram
