Overview of global Reference Systems (WRS) and summary of common tools

1. Introduction to the Global Reference System (WRS)

WRS (Worldwide Reference system) is one of the global reference systems used by Landsat satellites and an internationally representative global reference system. WRS is a fixed ground reference grid, which is based on the repetition characteristic of the satellite ground trajectory, which is combined with the imaging characteristics of the star. Its WRs reference grid is closely aligned with the imaging area of Landsat satellite data, and the two-dimensional coordinates of the WRS mesh are identified by path and row.

Currently WRS has two systems, WRS-1 (before 1983) and WRS-2 (after 1983). Landsat1-3 use WRS-2 with WRS-1,LANDSAT4, 5, 7, 8.

For us, the main purpose of understanding WRS is to make it easier to locate images. For example, we would like to download Landsat TM imagery data for a region, but we do not know the path/row of the area, and if we know about WRs, we can easily find the Path/row information for that area.

2.WR S-2 conversion between Path/row and Latitude/longitude

With the tools provided by NASA, you can easily convert between WRS-2 path/row and Latitude/longitude: http://landsat.usgs.gov/tools_latlong.php

The path/row of a known Landsat data region requires querying its latitude and longitude information, which can be done using the following methods:

Figure 1 Known path/row query latitude and longitude information

Conversely, if we know the latitude and longitude information for an area, it is also convenient to use the tool to query the Path/row of its corresponding Landsat data:

Figure 2 known latitude and longitude information query Path/row

3. wrs-1/2 vector file Download

: http://landsat.usgs.gov/tools_wrs-2_shapefile.php

From the above address can be downloaded to the global wrs-1/2 vector file (shp format), the basic information is as follows:

coverage : longitude-180°~ 180°/latitude-82.6°~ 82.6°

Projection Information : geographic Lat/lon

plane : WGS84

Unit : Decimal Degrees

at the same time, can be downloaded to global coverage WRS-2 the grid KML file and the KML file that covers the location of the WRS-2 center point in the West hemisphere. You can load the display directly on a KML-encoded geo-software such as Google Earth, and easily query the Path/row information for the corresponding region. For example: I want to query the Beijing city to use the Landsat8 path/row information, you can download to the global grid KML file loaded into Google Earth, and then locate in Beijing city, click the left mouse button to display the area of the Path/row (123/ 32) and other information (Figure 3).

Figure 3 Query area based on the KML file loaded onto Google Earth Path/row

4. WRS-1/2 Path/row and administrative divisions and latitude control in China

Figure 4 shows the WRS-1 reference system in China, the stripe number/row number and administrative divisions, the Latitude contrast chart:

Fig. 4 WRS-1 Path/row and administrative divisions and latitude and longitude of China in the scope of comparison

Figure 5 shows the WRS-2 reference system in China, the stripe number/row number and administrative divisions, the Latitude contrast chart:

Fig. 5 WRS-2 Path/row and administrative divisions and latitude and longitude of China in the scope of comparison

Resources:

1. http://www.gscloud.cn/page/page.shtml?pageid=C1B63222526359FF7EF1D5BFE166A5DC&tree=0

2. http://landsat.usgs.gov/worldwide_reference_system_WRS.php

3. http://blog.sina.com.cn/s/blog_4aa4593d0101jxgh.html

Reference Link: http://blog.sina.com.cn/s/blog_764b1e9d0102wdsm.html

Overview of global Reference Systems (WRS) and summary of common tools