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MATLAB 全景图切割及盒图显示的实现步骤

时间：2021-11-02 09:53     来源/作者：slandarer

part1 全景图切割

原图：

MATLAB 全景图切割及盒图显示的实现步骤

切割效果：

MATLAB 全景图切割及盒图显示的实现步骤
MATLAB 全景图切割及盒图显示的实现步骤

以下是切割部分步骤：
举这张图为例，图片格式hdr,jpg啥的都行：

MATLAB 全景图切割及盒图显示的实现步骤

1.1 边缘剔除

有些全景图会自带白灰色边缘，若是直接进行切割便会出现如下效果：

MATLAB 全景图切割及盒图显示的实现步骤

这时候我们首先要对原图进行白边剔除，代码如下：

oriPic=imread("test.hdr");
[rows,cols,~]=size(oriPic);

for i=cols:-1:1
    tempListR=oriPic(floor(rows/4):ceil(3*rows/4),i,1);
    tempListG=oriPic(floor(rows/4):ceil(3*rows/4),i,1);
    tempListB=oriPic(floor(rows/4):ceil(3*rows/4),i,1);
    if all(round(tempListR-mean(tempListR))==0)&&all(tempListR==tempListG)&&all(tempListR==tempListB)
        oriPic(:,i,:)=[];
    else
        break;
    end
end
oriPic=oriPic(:,end:-1:1,:);
for i=size(oriPic,2):-1:1
    tempListR=oriPic(floor(rows/4):ceil(3*rows/4),i,1);
    tempListG=oriPic(floor(rows/4):ceil(3*rows/4),i,1);
    tempListB=oriPic(floor(rows/4):ceil(3*rows/4),i,1);
    if all(round(tempListR-mean(tempListR))==0)&&all(tempListR==tempListG)&&all(tempListR==tempListB)
        oriPic(:,i,:)=[];
    else
        break;
    end
end
oriPic=oriPic(:,end:-1:1,:);
for i=rows:-1:1
    tempListR=oriPic(i,floor(cols/4):ceil(3*cols/4),1);
    tempListG=oriPic(i,floor(cols/4):ceil(3*cols/4),1);
    tempListB=oriPic(i,floor(cols/4):ceil(3*cols/4),1);
    if all(round(tempListR-mean(tempListR))==0)&&all(tempListR==tempListG)&&all(tempListR==tempListB)
        oriPic(i,:,:)=[];
    else
        break;
    end
end
oriPic=oriPic(end:-1:1,:,:);
for i=size(oriPic,1):-1:1
    tempListR=oriPic(i,floor(cols/4):ceil(3*cols/4),1);
    tempListG=oriPic(i,floor(cols/4):ceil(3*cols/4),1);
    tempListB=oriPic(i,floor(cols/4):ceil(3*cols/4),1);
    if all(round(tempListR-mean(tempListR))==0)&&all(tempListR==tempListG)&&all(tempListR==tempListB)
        oriPic(i,:,:)=[];
    else
        break;
    end
end
oriPic=oriPic(end:-1:1,:,:);

1.2 图像裁剪

我们要让完成的就是如下的变换和裁剪：

MATLAB 全景图切割及盒图显示的实现步骤
MATLAB 全景图切割及盒图显示的实现步骤

这部分其实已经有较为成熟的原理和代码：
代码参考：https://stackoverflow.com/questions/29678510/convert-21-equirectangular-panorama-to-cube-map

原理参考：
http://paulbourke.net/panorama/cubemaps/#1

http://paulbourke.net/panorama/cubemaps/

原理参考文章中更加清晰的变化图：

MATLAB 全景图切割及盒图显示的实现步骤

另：
在参考代码的基础上，对映射像素进行了插值处理，可以使图像更加平滑，原理如下：

MATLAB 全景图切割及盒图显示的实现步骤
MATLAB 全景图切割及盒图显示的实现步骤

主要函数代码：

function resultPic=createCubeMapFace(oriPic,id,height,width)
    [M,N,~]=size(oriPic);
    resultPic=zeros([height,width,3]);
    an=sin(pi/4);
    ak=cos(pi/4);
    
    faceTransform=[0,0;
               pi/2,0;
               pi,0;
               -pi/2,0;
               0,-pi/2;
               0,pi];
    ftu=faceTransform(id,1);
    ftv=faceTransform(id,2);

    for y=0:height-1
        for x=0:width-1
            nx=y/height-0.5;
            ny=x/width-0.5;

            nx=nx*2*an;
            ny=ny*2*an;

            if (ftv == 0)
                u=atan2(nx, ak);
                v=atan2(ny*cos(u),ak);
                u=u+ftu;
            elseif(ftv>0)
                d=sqrt(nx*nx+ny*ny);
                v=pi/2-atan2(d,ak);
                u=atan2(ny,nx);
            else
                d=sqrt(nx*nx+ny*ny);
                v=-pi/2+atan2(d,ak);
                u=atan2(-ny,nx);
            end

            u=u/(pi);
            v=v/(pi/2);

            while(v<-1)
                v=v+2;
                u=u+1;
            end
            while(v>1)
                v=v-2;
                u=u+1;
            end
            while(u<-1)
                u=u+2;
            end
            while(u>1)
                u=u-2;
            end
            u=u/2+0.5;
            v=v/2+0.5;

            u=u*(N-1)+1;
            v=v*(M-1)+1;
            
            fv=floor(v);fv1=floor(v)+1;pv=v-fv;fv1(fv1>M)=M;
            fu=floor(u);fu1=floor(u)+1;pu=u-fu;fu1(fu1>N)=N;
            resultPic(x+1,y+1,:)=double(oriPic(fv,fu,:)).*(1-pv).*(1-pu)+...
                                 double(oriPic(fv1,fu,:)).*(pv).*(1-pu)+...
                                 double(oriPic(fv,fu1,:)).*(1-pv).*(pu)+...
                                 double(oriPic(fv1,fu1,:)).*(pv).*(pu);
        end
    end
    resultPic=uint8(resultPic);
end

函数调用及图像存储：
这里后面长宽数值可以任意设定，但是要求长宽数值一致，如果按照当前写法，结果被存储至result文件夹：

if ~exist("result","dir")
   mkdir("result");
end

for i=1:6
    resultPic=createCubeMapFace(oriPic,i,500,500);
    figure(i)
    imshow(resultPic)
    imwrite(resultPic,["result",num2str(i),".jpg"])
end

另： 如图所示
图片序号[1,2,3,4,5,6]分别对应图片[右，后，左，前，上，下]

MATLAB 全景图切割及盒图显示的实现步骤

1.3 完整代码

function panoramic2box
oriPic=imread("889027-884424860.jpg");
[rows,cols,~]=size(oriPic);

for i=cols:-1:1
    tempListR=oriPic(floor(rows/4):ceil(3*rows/4),i,1);
    tempListG=oriPic(floor(rows/4):ceil(3*rows/4),i,1);
    tempListB=oriPic(floor(rows/4):ceil(3*rows/4),i,1);
    if all(round(tempListR-mean(tempListR))==0)&&all(tempListR==tempListG)&&all(tempListR==tempListB)
        oriPic(:,i,:)=[];
    else
        break;
    end
end
oriPic=oriPic(:,end:-1:1,:);
for i=size(oriPic,2):-1:1
    tempListR=oriPic(floor(rows/4):ceil(3*rows/4),i,1);
    tempListG=oriPic(floor(rows/4):ceil(3*rows/4),i,1);
    tempListB=oriPic(floor(rows/4):ceil(3*rows/4),i,1);
    if all(round(tempListR-mean(tempListR))==0)&&all(tempListR==tempListG)&&all(tempListR==tempListB)
        oriPic(:,i,:)=[];
    else
        break;
    end
end
oriPic=oriPic(:,end:-1:1,:);
for i=rows:-1:1
    tempListR=oriPic(i,floor(cols/4):ceil(3*cols/4),1);
    tempListG=oriPic(i,floor(cols/4):ceil(3*cols/4),1);
    tempListB=oriPic(i,floor(cols/4):ceil(3*cols/4),1);
    if all(round(tempListR-mean(tempListR))==0)&&all(tempListR==tempListG)&&all(tempListR==tempListB)
        oriPic(i,:,:)=[];
    else
        break;
    end
end
oriPic=oriPic(end:-1:1,:,:);
for i=size(oriPic,1):-1:1
    tempListR=oriPic(i,floor(cols/4):ceil(3*cols/4),1);
    tempListG=oriPic(i,floor(cols/4):ceil(3*cols/4),1);
    tempListB=oriPic(i,floor(cols/4):ceil(3*cols/4),1);
    if all(round(tempListR-mean(tempListR))==0)&&all(tempListR==tempListG)&&all(tempListR==tempListB)
        oriPic(i,:,:)=[];
    else
        break;
    end
end
oriPic=oriPic(end:-1:1,:,:);
% =========================================================================
if ~exist("result","dir")
   mkdir("result");
end

for i=1:6
    resultPic=createCubeMapFace(oriPic,i,500,500);
    figure(i)
    imshow(resultPic)
    imwrite(resultPic,["result",num2str(i),".jpg"])
end



% =========================================================================
function resultPic=createCubeMapFace(oriPic,id,height,width)
    [M,N,~]=size(oriPic);
    resultPic=zeros([height,width,3]);
    an=sin(pi/4);
    ak=cos(pi/4);
    
    faceTransform=[0,0;
               pi/2,0;
               pi,0;
               -pi/2,0;
               0,-pi/2;
               0,pi];
    ftu=faceTransform(id,1);
    ftv=faceTransform(id,2);

    for y=0:height-1
        for x=0:width-1
            nx=y/height-0.5;
            ny=x/width-0.5;

            nx=nx*2*an;
            ny=ny*2*an;

            if (ftv == 0)
                u=atan2(nx, ak);
                v=atan2(ny*cos(u),ak);
                u=u+ftu;
            elseif(ftv>0)
                d=sqrt(nx*nx+ny*ny);
                v=pi/2-atan2(d,ak);
                u=atan2(ny,nx);
            else
                d=sqrt(nx*nx+ny*ny);
                v=-pi/2+atan2(d,ak);
                u=atan2(-ny,nx);
            end

            u=u/(pi);
            v=v/(pi/2);

            while(v<-1)
                v=v+2;
                u=u+1;
            end
            while(v>1)
                v=v-2;
                u=u+1;
            end
            while(u<-1)
                u=u+2;
            end
            while(u>1)
                u=u-2;
            end
            u=u/2+0.5;
            v=v/2+0.5;

            u=u*(N-1)+1;
            v=v*(M-1)+1;
            
            fv=floor(v);fv1=floor(v)+1;pv=v-fv;fv1(fv1>M)=M;
            fu=floor(u);fu1=floor(u)+1;pu=u-fu;fu1(fu1>N)=N;
            resultPic(x+1,y+1,:)=double(oriPic(fv,fu,:)).*(1-pv).*(1-pu)+...
                                 double(oriPic(fv1,fu,:)).*(pv).*(1-pu)+...
                                 double(oriPic(fv,fu1,:)).*(1-pv).*(pu)+...
                                 double(oriPic(fv1,fu1,:)).*(pv).*(pu);
        end
    end
    resultPic=uint8(resultPic);
end
end

1.4 其他几组切割结果

图片源自：https://www.cgmodel.com/article/9004.html

MATLAB 全景图切割及盒图显示的实现步骤
MATLAB 全景图切割及盒图显示的实现步骤
MATLAB 全景图切割及盒图显示的实现步骤
MATLAB 全景图切割及盒图显示的实现步骤
MATLAB 全景图切割及盒图显示的实现步骤
MATLAB 全景图切割及盒图显示的实现步骤

part2 盒图展示

2.1 曲面绘制

使用surf绘制各个曲面后，并为各个曲面贴图：

for i=1:6
    oriPic.(["p",num2str(i)])=imread(["result",num2str(i),".jpg"]);   
end
[rows,cols,~]=size(oriPic.p1);
[baseXY,baseZ]=meshgrid(1:cols,rows:-1:1);

ax=gca;hold(ax,"on")


surf(baseXY(:,end:-1:1)-(1+rows)/2,-(rows-1)./2.*ones(size(baseXY)),baseZ,"CData",oriPic.p1,"EdgeColor","none","FaceColor","interp")
surf(-(rows-1)./2.*ones(size(baseXY)),baseXY-(1+rows)/2,baseZ,"CData",oriPic.p2,"EdgeColor","none","FaceColor","interp")
surf(baseXY-(1+rows)/2,(rows-1)./2.*ones(size(baseXY)),baseZ,"CData",oriPic.p3,"EdgeColor","none","FaceColor","interp")
surf((rows-1)./2.*ones(size(baseXY)),baseXY(:,end:-1:1)-(1+rows)/2,baseZ,"CData",oriPic.p4,"EdgeColor","none","FaceColor","interp")
surf(baseXY"-(1+rows)/2,baseXY-(1+rows)/2,ones(size(baseXY)),"CData",oriPic.p6(end:-1:1,end:-1:1,:),"EdgeColor","none","FaceColor","interp")
surf(baseXY"-(1+rows)/2,baseXY-(1+rows)/2,rows-1+ones(size(baseXY)),"CData",oriPic.p5(:,end:-1:1,:),"EdgeColor","none","FaceColor","interp")

MATLAB 全景图切割及盒图显示的实现步骤
MATLAB 全景图切割及盒图显示的实现步骤

2.2 视角调整

通过设置axes属性将视角调整至盒子里面

ax=axes("parent",fig,"position",[-0.45 -0.45 1.9 1.9]);hold(ax,"on")
ax.ZLim=[0,rows+1];
ax.XLim=[0-(1+rows)/2,rows+1-(1+rows)/2];
ax.YLim=[0-(1+rows)/2,rows+1-(1+rows)/2];
ax.Color=[0 0 0];
ax.CameraPosition=[0,0,rows/2];
ax.CameraPositionMode="manual";
ax.DataAspectRatio=[1,1,1];
ax.DataAspectRatioMode="manual";
ax.Projection="perspective";
ax.CameraTargetMode="manual";
ax.CameraViewAngle = 7;
ax.View=[-2.7391 90.0000];
ax.CameraTarget=[0 0 (rows-1)/2];
ax.Toolbar.Visible="on";

运行后点击那个三位旋转按钮即可开始漫游

MATLAB 全景图切割及盒图显示的实现步骤

此时的盒图是无缝隙版本，有缝隙版放在后面

MATLAB 全景图切割及盒图显示的实现步骤

2.3 完整代码

无缝隙版：

function showBox
for i=1:6
    oriPic.(["p",num2str(i)])=imread(["result",num2str(i),".jpg"]);   
end
[rows,cols,~]=size(oriPic.p1);
[baseXY,baseZ]=meshgrid(1:cols,rows:-1:1);

fig=figure("units","pixels","position",[300 80 500 500],...
                       "Numbertitle","off","menubar","none","resize","off",...
                       "name","box");
                   

ax=axes("parent",fig,"position",[-0.45 -0.45 1.9 1.9]);hold(ax,"on")
ax.ZLim=[0,rows+1];
ax.XLim=[0-(1+rows)/2,rows+1-(1+rows)/2];
ax.YLim=[0-(1+rows)/2,rows+1-(1+rows)/2];
ax.Color=[0 0 0];
ax.CameraPosition=[0,0,rows/2];
ax.CameraPositionMode="manual";
ax.DataAspectRatio=[1,1,1];
ax.DataAspectRatioMode="manual";
ax.Projection="perspective";
ax.CameraTargetMode="manual";
ax.CameraViewAngle = 7;
ax.View=[-2.7391 90.0000];
ax.CameraTarget=[0 0 (rows-1)/2];
ax.Toolbar.Visible="on";




surf(baseXY(:,end:-1:1)-(1+rows)/2,-(rows-1)./2.*ones(size(baseXY)),baseZ,"CData",oriPic.p1,"EdgeColor","none","FaceColor","interp")
surf(-(rows-1)./2.*ones(size(baseXY)),baseXY-(1+rows)/2,baseZ,"CData",oriPic.p2,"EdgeColor","none","FaceColor","interp")
surf(baseXY-(1+rows)/2,(rows-1)./2.*ones(size(baseXY)),baseZ,"CData",oriPic.p3,"EdgeColor","none","FaceColor","interp")
surf((rows-1)./2.*ones(size(baseXY)),baseXY(:,end:-1:1)-(1+rows)/2,baseZ,"CData",oriPic.p4,"EdgeColor","none","FaceColor","interp")
surf(baseXY"-(1+rows)/2,baseXY-(1+rows)/2,ones(size(baseXY)),"CData",oriPic.p6(end:-1:1,end:-1:1,:),"EdgeColor","none","FaceColor","interp")
surf(baseXY"-(1+rows)/2,baseXY-(1+rows)/2,rows-1+ones(size(baseXY)),"CData",oriPic.p5(:,end:-1:1,:),"EdgeColor","none","FaceColor","interp")

end

MATLAB 全景图切割及盒图显示的实现步骤

有缝隙版：

function showBox2
for i=1:6
    oriPic.(["p",num2str(i)])=imread(["result",num2str(i),".jpg"]);   
end
[rows,cols,~]=size(oriPic.p1);
[baseXY,baseZ]=meshgrid(1:cols,rows:-1:1);

fig=figure("units","pixels","position",[300 80 500 500],...
                       "Numbertitle","off","menubar","none","resize","off",...
                       "name","box");
                   

ax=axes("parent",fig,"position",[-0.45 -0.45 1.9 1.9]);hold(ax,"on")
ax.ZLim=[0,rows+1];
ax.XLim=[0-(1+rows)/2,rows+1-(1+rows)/2];
ax.YLim=[0-(1+rows)/2,rows+1-(1+rows)/2];
ax.Color=[0 0 0];
ax.CameraPosition=[0,0,rows/2];
ax.CameraPositionMode="manual";
ax.DataAspectRatio=[1,1,1];
ax.DataAspectRatioMode="manual";
ax.Projection="perspective";
ax.CameraTargetMode="manual";
ax.CameraViewAngle = 7;
ax.View=[-2.7391 90.0000];
ax.CameraTarget=[0 0 (rows+1)/2];
ax.Toolbar.Visible="on";




surf(baseXY(:,end:-1:1)-rows/2,-rows./2.*ones(size(baseXY)),baseZ,"CData",oriPic.p1,"EdgeColor","none","FaceColor","interp")
surf(-rows./2.*ones(size(baseXY)),baseXY-(1+rows)/2,baseZ,"CData",oriPic.p2,"EdgeColor","none","FaceColor","interp")
surf(baseXY-(1+rows)/2,rows./2.*ones(size(baseXY)),baseZ,"CData",oriPic.p3,"EdgeColor","none","FaceColor","interp")
surf(rows./2.*ones(size(baseXY)),baseXY(:,end:-1:1)-(1+rows)/2,baseZ,"CData",oriPic.p4,"EdgeColor","none","FaceColor","interp")
surf(baseXY"-(1+rows)/2,baseXY-(1+rows)/2,zeros(size(baseXY)),"CData",oriPic.p6(end:-1:1,end:-1:1,:),"EdgeColor","none","FaceColor","interp")
surf(baseXY"-(1+rows)/2,baseXY-(1+rows)/2,rows+ones(size(baseXY)),"CData",oriPic.p5(:,end:-1:1,:),"EdgeColor","none","FaceColor","interp")

end

MATLAB 全景图切割及盒图显示的实现步骤
MATLAB 全景图切割及盒图显示的实现步骤

以上就是MATLAB 全景图切割及盒图显示的详细内容，更多关于MATLAB 全景图的资料请关注服务器之家其它相关文章！

原文链接：https://blog.csdn.net/slandarer/article/details/116719145

标签：
matlab 全景图 

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