前段时间做了气象方面的工作，要在gis地图上叠加卫星影像。
gis地图是墨卡托投影，卫星影像是等经纬度投影，不能直接叠加。
于是整出了这个等经纬度影像 转 墨卡托影像的程序。
上代码：
import java.awt.image.BufferedImage;import java.io.File;import java.io.IOException;import java.util.ArrayList;import java.util.List;import javax.imageio.ImageIO;/** * 等经纬度影像 转 墨卡托影像 * 基本思路： * 1、赤道上经度跨越1度，其代表的距离恒定不变。 * 2、（经纬度影像）由起止经纬度可以计算出径向距离，得到径向有多少像素，从而可以计算出一像素代表多少米； * 3、纬度到赤道的距离有公式可以计算出，再由第2步得到的一像素代表多少米，就可以知道纬度需要多少像素填充。 * @author RainingTime * */public class LatLonImage2MercatorImage {public static void main(String[] args) throws IOException {long start = System.currentTimeMillis(); //原始数据起止经纬度{{开始纬度、开始经度}、{结束纬度、结束经度}}，左上角开始，右下角结束Double[][] sourceRange = {{53.817,60.2}, {4.83,138.78}};//裁剪区域起止经纬度{{开始纬度、开始经度}、{结束纬度、结束经度}}，左上角开始，右下角结束。//若不需要裁剪，则令cutRange = sourceRange Double[][] cutRange = {{53.817,60.2}, {4.83,138.78}}; String imageType = "png"; String source = "C:/Users/RainingTime/Desktop/FY4影像/FY4A_20210421074900000.jpg"; String outPut = "C:/Users/RainingTime/Desktop/FY4影像/FY4A_20210421074900000-mkt." + imageType; BufferedImage sourceImage = ImageIO.read(new File(source)); BufferedImage mercator = imageToMercator(sourceImage, sourceRange, cutRange, imageType);ImageIO.write(mercator, imageType, new File(outPut)); long end = System.currentTimeMillis(); System.out.println("转换完成，用时："+(end-start)+"ms");}/** * png、jpg影像转墨卡托投影 * @param sourcePath原始影像 * @param outPutPath输出影像 * @param sourceRange原始影像经纬度范围，要求左上角开始，右下角结束：{{开始纬度、开始经度}、{结束纬度、结束经度}} * @param cutRange裁剪区域经纬度范围，要求左上角开始，右下角结束：{{开始纬度、开始经度}、{结束纬度、结束经度}}，为null时默认不裁剪 * @param imageType输出影像格式，png、jpg两种 * @throws IOException */public static BufferedImage imageToMercator(BufferedImage sourceImage, Double[][] sourceRange, Double[][] cutRange, String imageType) throws IOException {double sourceStartLat = sourceRange[0][0];double sourceStartLon = sourceRange[0][1];double sourceEndLat = sourceRange[1][0];double sourceEndLon = sourceRange[1][1];double cutStartLat = sourceStartLat;double cutStartLon = sourceStartLon;double cutEndLat = sourceEndLat;double cutEndLon = sourceEndLon;if(cutRange != null){cutStartLat = cutRange[0][0];cutStartLon = cutRange[0][1];cutEndLat = cutRange[1][0];cutEndLon = cutRange[1][1];}if(sourceEndLat>sourceStartLat || sourceStartLon>sourceEndLon){System.out.println("数据源经纬度坐标从左上角开始，右下角结束！");return null;}if(cutEndLat>cutStartLat || cutStartLon>cutEndLon){System.out.println("裁剪区域经纬度坐标从左上角开始，右下角结束！");return null;}/** * earthRadius = 6378137;//地球赤道半径6378137米 * 20037508.3427892 = earthRadius * (math.pi - 0);//赤道周长的一半 * 85.05112877980659 = (math.atan(math.exp(aa / earthRadius))-math.pi/4)*2 * 180 / math.pi;//墨卡托最大有效纬度 */if(cutStartLat > 85.051128){System.out.println("墨卡托投影起始纬度最大为：85.051128，裁剪区域将被限定。");cutStartLat = 85.051128;}if(cutEndLat <- 85.051128){System.out.println("墨卡托投影终止纬度最小为：-85.051128，裁剪区域将被限定。");cutEndLat = -85.051128;} int sourceWidth = sourceImage.getWidth();int sourceHeight = sourceImage.getHeight();double lonStep = (sourceEndLon-sourceStartLon)/(sourceWidth-1);double latStep = (sourceEndLat-sourceStartLat)/(sourceHeight-1);System.out.println("sourceWidth: " + sourceWidth + ", sourceHeight: " + sourceHeight + ", latStep: " + latStep + ", lonStep: " + lonStep);int cutWidth = (int)((cutEndLon - cutStartLon)/lonStep + 0.5) + 1;int cutHeight = (int)((cutEndLat - cutStartLat)/latStep + 0.5) + 1;System.out.println("cutWidth: "+cutWidth+", cutHeight: "+cutHeight);//截止纬度与赤道之间有多少个点，北半球为正值int start = (int)((Math.log(Math.tan((90 + cutStartLat) * Math.PI / 360)) / (Math.PI / 180))/ lonStep + 0.5);//起始纬度与赤道之间有多少个点，南半球为负值int end = (int)((Math.log(Math.tan((90 + cutEndLat) * Math.PI / 360)) / (Math.PI / 180))/ lonStep + 0.5);int mwidth = cutWidth;//墨卡托投影宽度int mheight = start - end + 1;//墨卡托投影高度System.out.println("mwidth: "+mwidth+", mheight: "+mheight);//建立预设List<List<Integer>> list = new ArrayList<List<Integer>>();List<Integer> innerList = null;for(int y=0; y<mheight; y++){innerList = new ArrayList<Integer>();for(int x=0; x<mwidth; x++){innerList.add(0);//填充0，透明图层}list.add(innerList);innerList = null;}//填充真实数据int equator = -1;//赤道的像素y轴坐标BufferedImage outImage = null;if("png".equals(imageType)){outImage = new BufferedImage(mwidth, mheight, BufferedImage.TYPE_INT_ARGB);}else{outImage = new BufferedImage(mwidth, mheight, BufferedImage.TYPE_INT_RGB);}List<Integer> yIndexList = new ArrayList<Integer>(); for(int y=0; y<cutHeight; y++){double lat = cutStartLat + (y * latStep);//截止纬度 减 当前纬度，得到纬度差if(-85.051128 <= lat && lat <= 85.051128){int oy = start - (int)((Math.log(Math.tan((90 + lat) * Math.PI / 360)) / (Math.PI / 180)) / lonStep + 0.5);if(oy<mheight){yIndexList.add(oy);if(lat == 0.0 || (lat>0.0 && (lat+0.5*latStep)<0.0) || (lat<0.0 && (lat-0.5*latStep)>0.0)){//赤道equator = oy;}for(int x=0; x<cutWidth; x++){ int px = (int)((cutStartLon+x*lonStep-sourceStartLon)/lonStep + 0.5); int py = (int)((cutStartLat+y*latStep-sourceStartLat)/latStep + 0.5);int rgb = sourceImage.getRGB(px, py);list.get(oy).set(x, rgb);}}}}System.out.println("赤道的像素y轴坐标："+equator);for(int y=0; y<mheight; y++){if(y <= equator){for(int i=0; i<yIndexList.size(); i++){if(y == yIndexList.get(i)){for(int x=0; x<cutWidth; x++){outImage.setRGB(x, y, list.get(y).get(x));}break;} else if(y > yIndexList.get(i) && (i+1)<yIndexList.size() && y < yIndexList.get(i+1)){for(int x=0; x<cutWidth; x++){outImage.setRGB(x, y, list.get(yIndexList.get(i+1)).get(x));}break;}}} else {for(int i=0; i<yIndexList.size(); i++){if(y == yIndexList.get(i)){for(int x=0; x<cutWidth; x++){outImage.setRGB(x, y, list.get(y).get(x));}break;} else if(y > yIndexList.get(i) && (i+1)<yIndexList.size() && y < yIndexList.get(i+1)){for(int x=0; x<cutWidth; x++){outImage.setRGB(x, y, list.get(yIndexList.get(i)).get(x));}break;}}}}list = null;return outImage;}}原图：风云四A星真彩色云图，来源：http://www.nmc.cn/publish/satellite/FY4A-true-color.htm
输出：因为不能上传大于5M的图片，这里将图片压缩了下才上传的。
传送门：墨卡托影像 转 等经纬度影像，墨卡托图片 转 等经纬度图片