China releases first nationwide geometric reference imagery

China's Ministry of Natural Resources released the country's first geometric reference imagery covering all land territory on August 27, providing a unified spatial benchmark for remote sensing imagery nationwide.

With a resolution of better than 0.5 meters, the dataset is designed to serve as a common "spatial ruler" for satellite imagery and improve the accuracy and consistency of remote sensing data.

Zhou Ping, director of the Data Processing Department at the Land Satellite Remote Sensing Application Center under the Ministry of Natural Resources, said images produced by different satellites can vary in geometric quality, making it difficult to align them accurately.

"Roads can appear discontinuous or misaligned" when different satellite images are overlaid, Zhou said. Using the geometric reference imagery, however, features such as the area of buildings and the length and direction of roads can be accurately aligned across images.

The need for a unified reference has become increasingly important as China's commercial remote sensing satellite sector expands rapidly. The lack of consistent imaging benchmarks has been a constraint on the industry's development.

By using the geometric reference imagery as a base map, companies and institutions can calibrate raw satellite imagery and ensure accurate alignment.

The dataset also addresses technical challenges in controlling imaging accuracy in mountainous and plateau areas, raising the overall positioning accuracy of remote sensing imagery across China by more than twofold, according to the ministry.

Yu Dequan, deputy director of the Land Satellite Remote Sensing Application Center, said the center has established China's first geometric reference imagery covering the country's entire land territory, with the highest overall accuracy to date.

The dataset will be promoted for use in building China's 3D real-world mapping system, natural resources surveys and monitoring, and commercial satellite remote sensing, Yu said.

The imagery will be made openly available to the public, which is expected to significantly reduce imagery production costs across industries and accelerate the development of satellite remote sensing applications.

Sun Hua, a senior researcher at the ministry's Department of Land Surveying and Mapping, said authorities will develop guidelines this year to standardize the use of the geometric reference imagery and ensure its efficient, secure and controlled application.

Authorities will also work with relevant departments to develop measures encouraging commercial satellite companies to make full use of the dataset, helping foster new business models and an ecosystem for the satellite remote sensing industry.