Basic images
  • L1R : Images with radiometric correction applied by KARI
  • L1G : Images with geometric correction applied for L1R using orbit information by KARI
한국항공우주연구원과 국토지리정보원간 교류
Calibration for production of basic images
  • Raw data
  • 방사보정, 대기보정, 기하보정 설명
    Radiometric correction Geometric correction
    Radiometric correction enhances the accuracy of the pixel values by addressing distortions caused the sensitivity of the satellite sensor over time or across its field of view can affect the image data. Geometric correction overcomes the distortions in the geometric relationship between the sensor and ground objects due to Earth's rotation, Earth's curvature, and satellite orbital errors.
  • 기본영상(L1R, L1G)

    Basic images
    (L1R and L1G)

Corrected images
  • Improved position accuracy (dozens of meters to several meters), improved spatial resolution (2m to 0.5m)
  • Precisely corrected images (L2R): the images with precise geometric correction applied for L1G using GCPs
  • Satellite orthoimages (L2G): the images with orthorectificaion applied for L2R by eliminating relief displacement and aligning each pixel's coordinates using DEM
GCP Chip을 이용한 기하보정 영상 - 기하보정 전 영상(기본영상 L1R) → GCP Chip - 위성영상 간 매칭 → 기하보정 된 영상(정밀보정영상L2R) → 수치표고모형(DEM) → 기하정사보정 완료 영상(위성정사영상L2G)
Process of orthorectification
위성정사영상 처리 과정
Introduction to GCP chips
  • Reference points in image format used for the automatic geometric correction of satellite images
  • Constructed from aerial orthophotos cropped to a certain size around national official GCPs
GCP Chip
gcp chip 설명
Item Description
Chip number ID number of GCP chips
Ground coordinates National unified GCPs
Ground coordinate representation Latitude, longitude, and altitude
Data source Aerial orthophotos
Chip size 1027×1027 pixels
Spatial resolution 0.25m
Spectral bands Blue, Green, and Red
Geometric correction of CAS500 images using GCP chips
기하보정전 위치정확도 약60~100m 위성영상-위성영상기준점 매칭 기하보정후 위치정확도 약0.5~2m
Basic plans for national GCP chip construction
  1. 01. Construction and standardization plans

    ACT 1 GCP Chip construction plans for CAS500 images

    ACT 2 Preparation for the standardization, shared utilization, and legislation of GCP chip construction

  2. 02. Database construction and update

    ACT 3 GCP chip database update for CAS500 images

    ACT 4 Various GCP chip construction nationwide

  3. 03. System development

    ACT 5 System design for automated construction of GCP chips, QA, distribution, and maintenance

    ACT 6 System implementation

  4. 04. Governance

    ACT 7 Operation of and inter-organizational initiative for GCP chip utilization

    ACT 8 Establishment of international cooperation for GCP chip construction for CAS500 images

Introduction to national GCP chips
GCP chip specification for orthorectification
남한과 북한의 GCP Chip 사양
Item South Korea North Korea
Ground coordinates used Unified control points, photo control points, and triangular control points Photo control points
Data source NGII aerial orthophoto Satellite images
Coordinate reference system GRS80 / UTM-K GRS80 / UTM-K
Spectral bands Blue, Green, and Red Panchromatic
Spatial resolution 0.25m 0.5m
Image size 1027×1027 pixels 513×513 pixels
Quantity Approximately 25,000 Approximately 25,000
GCP chip
example		 남한GCP Chip 형태 예시 북한GCP Chip 형태 예시