51 DITU map API map scale and Coordinate Transformation

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• Proportional level definition table

Proportional level definition table

 

The proportion level used has a total of 13 levels ranging from 0 to 12. Their correspondence with the actual scale is as follows:

Level 0 -------------------- 1: 25 m
Level 1 -------------------- 1: 50 m
Level 2 -------------------- 1: 100 m
Level 3 -------------------- 1: 250 m
Level 4 -------------------- 1: 500 m
Level 5 -------------------- 1: 1 km
Level 6 --------------------. 5 km
Level 7 -------------------- 1: 5 km
Level 8 -------------------- 1: 10 km
Level 9 -------------------- 1: 25 km
Level 10 ------------------- 1: 50 km
Grade 11 ------------------- 1: 100 km
Level 12 ------------------- 1: 500 km

In short, 0-level maps are the most detailed, and 12-level maps are the simplest.

 

The longitude and latitude units used in the map application interface are NTU. You need to convert the longitude and latitude values of other units. The following are common conversion relationships:

Basic conversion: NTU = degree * 100000 Degree = NTU/100000 For example: Longitude = 116.21345 ° Latitude = 39.445875 ° NTU longitude: 116.21345*100000 = 11621345 (NTU) NTU latitude: 39.445874*100000 = 3944587 (NTU) Degree conversion: Convert degrees into units Degree = degree + minute/60 For example: Longitude = 116 ° 20. 12' Latitude = 39 ° 12. 34' Longitude = 116 + 20.12/60 = 116.33533 ° Latitude = 39 + 12.34/60 = 39.20567 ° NTU longitude = 116.33533*100000 = 11633533 (NTU) NTU latitude = 39.20567*100000 = 3920567 (NTU) Degree-to-Second Conversion: Converts the data in the unit of measure to the data in the unit of measure. Degree = degree + minute/60 + seconds/60/60 For example: Longitude = 116 ° 20' 43" Latitude = 39 ° 12' 37" Longitude = 116 + 20/60 + 43/60/60 = 116.34528 ° Latitude = 39 + 12/60 + 37/60/60 = 39.21028 ° NTU longitude = 116.34528*100000 = 11634528 (NTU) NTU latitude = 39.21028*100000 = 3921028 (NTU) The latitude and longitude values in the format are converted first, and then the preceding calculation is used.

You can use the latitude and longitude unit conversion tool to convert

• All the longitude and latitude of the map interface are irreversible encrypted. Therefore, before using the map interface, you must encrypt the real longitude and latitude (unit: NTU, you can use the encryption tool to convert the real latitude and longitude into the encrypted latitude and longitude.

Basic knowledge related to longitude and latitude:

NTU is equivalent to one in 100,000.

How to calculate the longitude distance

For example, if the latitude of Point A is 3995400 and that of point B is 3995300, the difference between the two points is 100 meters along the weft.
The longitude of Point A is 11695400, And the longitude of point B is 11695300. The difference between the two points is about 77 meters along the longitude line,
The approximate formula can be used to calculate the value:
Longitude distance = longitude difference * Cos (latitude value) = 100 * Cos (39) = 77 meters.

How to calculate the distance between two points

For example, the longitude of Point A is 11695400, And the latitude is 3995400. The longitude of point B is 11695300, And the latitude is 3995300.
Formula: distance between two points = [(a point longitude-B point longitude) ^ 2 + (a point latitude-B point latitude) ^ 2] ^ (1/2) = [(11695400-11695300) ^ 2
+ (3995400-3995300) ^ 2] ^ (1/2) = (10000 + 10000) ^ (1/2) = 141 meters

Formula Description: addition +, subtraction-, multiplication *, Division/, power operation ^ (1/2) represents the square root ^ 2 represents the square.