System and method for automatic geometric correction using RPC
View Patent ↗The present invention relates to a technique for correcting a geometric image error calculated as a rational polynomial coefficient (RPC) only through a corresponding point extracted from a digital elevation model (DEM) and a stereoscopic image without direct measurement of a ground control point (GCP). To this end, a system for automatic geometric correction using an RPC in accordance with the present invention comprises: an auxiliary data extraction unit; a corresponding point extraction unit; a first ground coordinate extraction unit; a second ground coordinate extraction unit; an RPC correction model generation unit; and an image distortion correction unit. The auxiliary data extraction unit extracts two or more different images captured from the same ground surface and auxiliary data of the two or more different images. The corresponding point extraction unit extracts a corresponding point from the two or more different images through image matching. The first ground coordinate extraction unit extracts first ground coordinates from the corresponding point and an RPC model of the auxiliary data. The second ground coordinate extraction unit extracts second ground coordinates by using the first ground coordinates and a correlation coefficient of a DEM. The RPC correction model generation unit generates an RPC correction model by correcting the RPC model on the basis of the second ground coordinates. The image distortion correction unit corrects distortion of an image by allocating ground coordinates to each image coordinates of the image by using the second ground coordinates and the RPC correction model.
1. A system for automatic geometric correction using rational polynomial coefficients (RPCs), comprising:
a processor configured to:
extract two or more different images, acquired by photographing a same ground surface, and auxiliary data on the images;
extract a tie point from the two or more different images through image matching;
extract first ground coordinates from the tie point and an RPC (rational polynomial coefficient) model of the auxiliary data;
extract second ground coordinates using the first ground coordinates and correlation coefficients of a digital elevation model;
generate an RPC correction model by correcting the RPC model based on the second ground coordinates; and
correct distortion of the images by allocating ground coordinates to each set of image coordinates of the images using the second ground coordinates and the RPC correction model.
2. The system of claim 1 , wherein the processor is further configured to:
calculate an error in an X direction and an error in a Y direction between the first ground coordinates and the second ground coordinates;
analyze error tendency of the calculated X- and Y-direction errors in image column and line directions; and
correct the X- and Y-direction errors based on the analysis.
3. The system of claim 1 , wherein the processor is further configured to correct the RPC model using the second ground coordinates and the RPC correction model, thereby allocating ground coordinates to each set of image coordinates of the images.
4. A method for automatic geometric correction using rational polynomial coefficients (RPCs), comprising the steps of:
(a) extracting two or more different images, acquired by photographing a same ground surface, and auxiliary data on the images;
(b) extracting a tie point from the two or more different images through image matching;
(c) extracting first ground coordinates from the tie point and an RPC (rational polynomial coefficient) model of the auxiliary data;
(d) extracting second ground coordinates using the first ground coordinates and correlation coefficients of a digital elevation model;
(e) generating an RPC correction model by correcting the RPC model based on the second ground coordinates; and
(f) correcting distortion of the images by allocating ground coordinates to each set of image coordinates of the images using the second ground coordinates and the RPC correction model.
5. The method of claim 4 , wherein step (e) comprises:
calculating an error in an X direction and an error in a Y direction between the first ground coordinates and the second ground coordinates;
analyzing error tendency of the calculated X- and Y-direction errors in image column and line directions; and
correcting the X- and Y-direction errors based on the analysis.
6. The method of claim 4 , wherein step (f) comprises correcting the RPC model using the second ground coordinates and the RPC correction model, thereby allocating ground coordinates to each set of image coordinates of the images.
7. A non-transitory computer-readable storage medium having stored therein a program configured to perform a method of claim 4 .