jiayuasu commented on code in PR #1061:
URL: https://github.com/apache/sedona/pull/1061#discussion_r1376822795
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common/src/main/java/org/apache/sedona/common/raster/RasterAccessors.java:
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@@ -127,6 +128,70 @@ public static String getGeoReference(GridCoverage2D
raster, String format) {
}
}
+
+ public static double[] getGeoTransform(GridCoverage2D raster) throws
FactoryException {
+ // size of a pixel along the transformed i axis
+ double magnitudeI;
+
+ // size of a pixel along the transformed j axis
+ double magnitudeJ;
+
+ // angle by which the raster is rotated (Radians positive clockwise)
+ double thetaI;
+
+ // angle from transformed i axis to transformed j axis (Radians
positive counter-clockwise)
+ double thetaIJ;
+
+ RenderedImage renderedImage = raster.getRenderedImage();
+
+ // x ordinate of the upper-left corner of the upper-left pixel
+ double offsetX = renderedImage.getTileGridXOffset();
+
+ // y ordinate of the upper-left corner of the upper-left pixel
+ double offsetY = renderedImage.getTileGridYOffset();
+
+ double[] metadata = metadata(raster);
+ double scaleX = metadata[4];
+ double scaleY = metadata[5];
+ double skewX = metadata[6];
+ double skewY = metadata[7];
+
+ // pixel size in i direction - west-east
+ magnitudeI = Math.sqrt(scaleX * scaleX + skewY * skewY);
+
+ // pixel size in j direction - north-south
+ magnitudeJ = Math.sqrt(scaleY * scaleY + skewX * skewX);
+
+ // Rotation
+ thetaI = Math.acos(scaleX / magnitudeI);
+ double thetaTest = Math.acos(skewY / magnitudeI);
+ if (thetaTest < Math.PI / 2) {
+ thetaI = -thetaI;
+ }
+
+ // Angular separation
+ thetaIJ = Math.acos((((scaleX * skewX) + (skewY * scaleY)) /
(magnitudeI * magnitudeJ)));
Review Comment:
can `magnitude` be zero or other invalid values? If so, we need to add
handlers and test cases.
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