【发布时间】：2019-01-22 23:08:31
【问题描述】：
过去两天，我一直在尝试将 360 度相机、单鱼眼图像转换为节点 js 中的 equirectangular 查看器。在 stackoverflow 中，同样的问题在伪代码中被询问和回答。我一直在尝试将伪代码转换为节点 js 并清除了一些错误。现在项目运行没有错误，但输出图像是空白的。
从那个伪中，我不知道 polar_w、polar_h 和 geo_w、geo_h、geo 和 polar 值，所以它给出了静态值来显示输出。这是我将伪代码转换为节点 js 的链接。 How to convert spherical coordinates to equirectangular projection coordinates?.
这是我尝试将球面图像转换为 equirectangular 查看器的代码：
exports.sphereImage=(request, response)=>{
var Jimp = require('jimp');
// Photo resolution
var img_w_px = 1280;
var img_h_px = 720;
var polar_w = 1280;
var polar_h = 720;
var geo_w = 1280;
var geo_h = 720;
var img_h_deg = 70;
var img_w_deg = 30;
// Camera field-of-view angles
var img_ha_deg = 70;
var img_va_deg = 40;
// Camera rotation angles
var hcam_deg = 230;
var vcam_deg = 60;
// Camera rotation angles in radians
var hcam_rad = hcam_deg/180.0*Math.PI;
var vcam_rad = vcam_rad/180.0*Math.PI;
// Rotation around y-axis for vertical rotation of camera
var rot_y = [
[Math.cos(vcam_rad), 0, Math.sin(vcam_rad)],
[0, 1, 0],
[-Math.sin(vcam_rad), 0, Math.cos(vcam_rad)]
];
// Rotation around z-axis for horizontal rotation of camera
var rot_z = [
[Math.cos(hcam_rad), -Math.sin(hcam_rad), 0],
[Math.sin(hcam_rad), Math.cos(hcam_rad), 0],
[0, 0, 1]
];
Jimp.read('./public/images/4-18-2-42.jpg', (err, lenna) => {
polar = new Jimp(img_w_px, img_h_px);
geo = new Jimp(img_w_px, img_h_px);
for(var i=0; i<img_h_px; ++i)
{
for(var j=0; j<img_w_px; ++j)
{
// var p = img.getPixelAt(i, j);
var p = lenna.getPixelColor(i, j)
// var p = getPixels(img, { x: i, y: j })
// Calculate relative position to center in degrees
var p_theta = (j - img_w_px / 2.0) / img_w_px * img_w_deg / 180.0 * Math.PI;
var p_phi = -(i - img_h_px / 2.0) / img_h_px * img_h_deg / 180.0 *Math. PI;
// Transform into cartesian coordinates
var p_x = Math.cos(p_phi) * Math.cos(p_theta);
var p_y = Math.cos(p_phi) * Math.sin(p_theta);
var p_z = Math.sin(p_phi);
var p0 = {p_x, p_y, p_z};
// Apply rotation matrices (note, z-axis is the vertical one)
// First vertically
var p1 = rot_y[1][2][3] * p0;
var p2 = rot_z[1][2][3] * p1;
// Transform back into spherical coordinates
var theta = Math.atan2(p2[1], p2[0]);
var phi = Math.asin(p2[2]);
// Retrieve longitude,latitude
var longitude = theta / Math.PI * 180.0;
var latitude = phi / Math.PI * 180.0;
// Now we can use longitude,latitude coordinates in many different
projections, such as:
// Polar projection
{
var polar_x_px = (0.5*Math.PI + phi)*0.5 * Math.cos(theta)
/Math.PI*180.0 * polar_w;
var polar_y_px = (0.5*Math.PI + phi)*0.5 * Math.sin(theta)
/Math.PI*180.0 * polar_h;
polar.setPixelColor(p, polar_x_px, polar_y_px);
}
// Geographical (=equirectangular) projection
{
var geo_x_px = (longitude + 180) * geo_w;
var geo_y_px = (latitude + 90) * geo_h;
// geo.setPixel(geo_x_px, geo_y_px, p.getRGB());
geo.setPixelColor(p, geo_x_px, geo_y_px);
}
// ...
}
}
geo.write('./public/images/4-18-2-42-00001.jpg');
polar.write('./public/images/4-18-2-42-00002.jpg');
});
}
并尝试了另一种方法，将图像分成四个部分来检测汽车。使用 image-slice 模块将图像切成四部分，并使用 jimp 模块进行读写。但不幸的是，无法正确检测到汽车。
这是我用于切片图像的代码：
exports.sliceImage=(request, response)=>{
var imageToSlices = require('image-to-slices');
var lineXArray = [540, 540];
var lineYArray = [960, 960];
var source = './public/images/4-18-2-42.jpg'; // width: 300, height: 300
imageToSlices(source, lineXArray, lineYArray, {
saveToDir: './public/images/',
clipperOptions: {
canvas: require('canvas')
}
}, function() {
console.log('the source image has been sliced into 9 sections!');
});
}//sliceImage
为了从图像中检测汽车，我使用了 opencv4nodejs。未正确检测到汽车。这是我用于检测汽车的代码：
function runDetectCarExample(img=null){
if(img==null){
img = cv.imread('./public/images/section-1.jpg');
}else
{
img=cv.imread(img);
}
const minConfidence = 0.06;
const predictions = classifyImg(img).filter(res => res.confidence > minConfidence && res.className=='car');
const drawClassDetections = makeDrawClassDetections(predictions);
const getRandomColor = () => new cv.Vec(Math.random() * 255, Math.random() * 255, 255);
drawClassDetections(img, 'car', getRandomColor);
cv.imwrite('./public/images/section-'+Math.random()+'.jpg', img);
var name="distanceFromCamera";
var focalLen= 1.6 ;//Focal length in mm
var realObjHeight=254 ;//Real Height of Object in mm
var cameraFrameHeight=960;//Height of Image in pxl
var imgHeight=960;//Image Height in pxl
var sensorHeight=10;//Sensor height in mm
var R = 6378.1 //#Radius of the Earth
var brng = 1.57 //#Bearing is 90 degrees converted to radians.
var hc=(200/100);//Camera height in m
predictions
.forEach((data)=> {
// imgHeight=img.rows;//Image Height in pxl
// realObjHeight=data.rect.height;
// data.rect[name]=((focalLen)*(realObjHeight)*
(cameraFrameHeight))/((imgHeight)*(sensorHeight));
var dc=(((data.rect.width * focalLen) / img.cols)*2.54)*100; // meters
console.log(Math.floor(parseInt(data.rect.width)));
// var dc=((Math.floor(parseInt(data.rect.width)* 0.264583) * focalLen) / img.cols); // mm
var lat1=13.0002855;//13.000356;
var lon1=80.2046441;//80.204632;
// Gate 13.0002855,80.2046441
// Brazil Polsec : -19.860566, -43.969436
// var d=Math.sqrt((dc*dc)+(hc*hc));
// d=(data.rect[name])/1000;
data.rect[name]=d=dc/1000;
lat1 =toRadians(lat1);
lon1 = toRadians(lon1);
brng =toRadians(90);
// lat2 = Math.asin( Math.sin(lat1)*Math.cos(d/R) +
// Math.cos(lat1)*Math.sin(d/R)*Math.cos(brng));
// lon2 = lon1 +
Math.atan2(Math.sin(brng)*Math.sin(d/R)*Math.cos(lat1),
// Math.cos(d/R)-Math.sin(lat1)*Math.sin(lat2));
var lat2 = Math.asin(Math.sin(lat1) * Math.cos(d/6371) +
Math.cos(lat1) * Math.sin(d/6371) * Math.cos(brng));
var lon2 = lon1 + Math.atan2(Math.sin(brng) * Math.sin(d/6371) * Math.cos(lat1),
Math.cos(d/6371) - Math.sin(lat1) * Math.sin(lat2));
lat2 = toDegrees(lat2);
lon2 = toDegrees(lon2);
data.rect['latLong']=lat2+','+lon2;
// console.log(brng);
});
response.send(predictions);
cv.imshowWait('img', img);
};
这里是需要转换成等距矩形的鱼眼图像。
非常感谢任何帮助......
【问题讨论】：
-
这是很多代码供我们在这里切入以查找问题，尤其是当您还没有明确说明问题的真正含义时。我认为你需要做的是精简它，专注于问题的核心，并使用像 Mocha 这样的单元测试框架编写测试，明确定义一系列输入值的预期行为。
-
你应该清理你的问题，并坚持你所问的抽象核心。您需要的是鱼眼投影映射到等角投影。在复制并粘贴答案中的代码之前，最好先了解一下这到底是什么。
标签： javascript node.js image-processing three.js projection