/*
* Copyright (c) 2011-2016, Peter Abeles. All Rights Reserved.
*
* This file is part of BoofCV (http://boofcv.org).
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package boofcv.alg.distort.spherical;
import georegression.geometry.ConvertCoordinates3D_F64;
import georegression.metric.UtilAngle;
import georegression.misc.GrlConstants;
import georegression.struct.point.Point2D_F64;
import georegression.struct.point.Point3D_F64;
/**
* Contains common operations for handling coordinates in an equirectangular image.
* On most globes, a positive latitude corresponds to the north pole, or up, and negative towards the south pole.
* Images have 0 on the top and increase downwards. To compensate for this the y-axis can be flipped. This
* is indicated by functions with FV (flip vertical) on the end of their name.
*
* Coordinate System:
* <ul>
* <li>longtitude is along the x-axis and goes from -pi to pi</li>
* <li>latitude is along the y-axis and goes from -pi/2 to pi/2</li>
* <li>image center (width/2, (height-1)/2.0) or (lat=0, lon=0) corresponds to a unit sphere of (1,0,0)</li>
* <li>unit sphere of (0,0,1) is pixel (width/2,0) and (0,0,-1) is (width/2,height-1)</li>
* <li>unit sphere of (0,1,0) is pixel (3*width/4,(height-1)/2) and (0,0,-1) is (width/4,(height-1)/2)</li>
* </ul>
* Coordinate System with y-flipped:
* <ul>
* <li>longtitude is along the x-axis and goes from -pi to pi</li>
* <li>latitude is along the y-axis and goes from pi/2 to -pi/2</li>
* <li>image center (width/2, height/2) or (lat=0, lon=0) corresponds to a unit sphere of (1,0,0)</li>
* <li>unit sphere of (0,0,1) is pixel (width/2,height-1) and (0,0,-1) is (width/2,0)</li>
* <li>unit sphere of (0,1,0) is pixel (3*width/4,(height-1)/2) and (0,0,-1) is (width/4,(height-1)/2)</li>
* </ul>
*
* @author Peter Abeles
*/
public class EquirectangularTools_F64 {
// input image width and height
int width;
int height;
// internal storage to avoid declaring new memory
Point2D_F64 temp = new Point2D_F64();
/**
* Specifies the image and which latitude/longtiude will comprise the center axises
* @param width Image width
* @param height Image height
*/
public void configure( int width , int height ) {
this.width = width;
this.height = height;
}
/**
* Converts equirectangular into normalized pointing vector
*
* @param x pixel coordinate in equirectangular image
* @param y pixel coordinate in equirectangular image
* @param norm Normalized pointing vector
*/
public void equiToNorm(double x , double y , Point3D_F64 norm ) {
equiToLonlat(x,y, temp);
ConvertCoordinates3D_F64.latlonToUnitVector(temp.y,temp.x, norm);
}
public void normToEqui( double nx , double ny , double nz , Point2D_F64 rect ) {
/**/double r = /**/Math.sqrt(nx*nx + ny*ny);
/**/double lon = /**/Math.atan2(ny,nx);
/**/double lat = UtilAngle.atanSafe(-nz,r);
lonlatToEqui( (double) lon, (double) lat,rect);
}
public void equiToNormFV(double x , double y , Point3D_F64 norm ) {
equiToLonlatFV(x,y, temp);
ConvertCoordinates3D_F64.latlonToUnitVector(temp.y,temp.x, norm);
}
public void normToEquiFV( double nx , double ny , double nz , Point2D_F64 rect ) {
/**/double r = /**/Math.sqrt(nx*nx + ny*ny);
/**/double lon = /**/Math.atan2(ny,nx);
/**/double lat = UtilAngle.atanSafe(-nz,r);
lonlatToEquiFV( (double) lon, (double) lat,rect);
}
/**
* Converts the equirectangular coordinate into a latitude and longitude
* @param x pixel coordinate in equirectangular image
* @param y pixel coordinate in equirectangular image
* @param lonlat (output) x = longitude, y = latitude
*/
public void equiToLonlat(double x , double y , Point2D_F64 lonlat ) {
lonlat.x = (x/width - 0.5)*GrlConstants.PI2; // longitude
lonlat.y = (y/(height-1) - 0.5)*GrlConstants.PI; // latitude
}
/**
* <p>
* Converts the equirectangular coordinate into a latitude and longitude.
* Vertical equirectangular axis has been flipped
* </p>
* y' = height - y - 1
*
* @param x pixel coordinate in equirectangular image
* @param y pixel coordinate in equirectangular image
* @param lonlat (output) x = longitude, y = latitude
*/
public void equiToLonlatFV(double x , double y , Point2D_F64 lonlat ) {
lonlat.x = (x/width - 0.5)*GrlConstants.PI2; // longitude
lonlat.y = ((height-y-1.0)/(height-1) - 0.5)*GrlConstants.PI; // latitude
}
/**
* Convert from latitude-longitude coordinates into equirectangular coordinates
* @param lon Longitude
* @param lat Latitude
* @param rect (Output) equirectangular coordinate
*/
public void lonlatToEqui(double lon , double lat , Point2D_F64 rect ) {
rect.x = UtilAngle.wrapZeroToOne(lon / GrlConstants.PI2 + 0.5)*width;
rect.y = UtilAngle.reflectZeroToOne(lat / GrlConstants.PI + 0.5)*(height-1);
}
/**
* Convert from latitude-longitude coordinates into equirectangular coordinates.
* Vertical equirectangular axis has been flipped
* @param lon Longitude
* @param lat Latitude
* @param rect (Output) equirectangular coordinate
*/
public void lonlatToEquiFV(double lon , double lat , Point2D_F64 rect ) {
rect.x = UtilAngle.wrapZeroToOne(lon / GrlConstants.PI2 + 0.5)*width;
rect.y = UtilAngle.reflectZeroToOne(lat / GrlConstants.PI + 0.5)*(height-1);
rect.y = height - rect.y - 1;
}
}