基于cornerstone3D的dicom影像浏览器 第二十七章 设置vr相机，复位视图

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前言

1. VR窗口通过设置相机显示“前视( A )”、“后视( P )”、“左视( L )”、“右视( R )”、“俯视( S )”、“仰视( I )” 图像
2. 实现各视图复位功能
   效果如下：
   

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一、VR视图设置相机位置

1. 相机位置参数

vtk坐标系，以人体为例：
x 轴正向： 从右至左 [1,0,0]，反向：从左至右[-1,0,0]
y轴正向：从前至后[0,1,0]，反向：从后至前[0,-1,0]
z轴正向：从下至上[0,0,1]，反向：从上至下[0,0,-1]
相机的两个参数：

1. viewPlaneNormal，视平面法向量，与视线相反的方向。如相机对着物体拍摄，从物体指向相机镜头的方向就是视平面法向量。
2. viewUp，相机向上的方向

于是可得以下参数：
前视( A ): viewPlaneNormal即为y轴反向[0, -1, 0]，viewUp z轴正向[0,0,1]
后视( P ): viewPlaneNormal即为y轴正向[0, 1, 0]，viewUp z轴正向[0,0,1]
左视( L ): viewPlaneNormal即为x轴正向[1, 0, 0]，viewUp z轴正向[0,0,1]
右视( R ): viewPlaneNormal即为x轴反向[-1, 0, 0]，viewUp z轴正向[0,0,1]
俯视( S ): viewPlaneNormal即为z轴正向[0, 0, 1]，viewUp y轴正向[0,1,0]或反向[0,-1,0]
仰视( I ): viewPlaneNormal即为z轴反向[0, 0, -1]，viewUp y轴反向[0,-1,0]

2. 修改mprvr.js

1. 获取viewport camera
2. 设置camera两个参数viewPlaneNormal、viewUp
3. 调用viewport.resetCamera()应用生效

const cameraPos = {A: {viewPlaneNormal: [0, -1, 0],viewUp: [0, 0, 1]},P: {viewPlaneNormal: [0, 1, 0],viewUp: [0, 0, 1]},L: {viewPlaneNormal: [1, 0, 0],viewUp: [0, 0, 1]},R: {viewPlaneNormal: [-1, 0, 0],viewUp: [0, 0, 1]},S: {viewPlaneNormal: [0, 0, 1],viewUp: [0, 1, 0]},I: {viewPlaneNormal: [0, 0, -1],viewUp: [0, -1, 0]}
};export default class MPR {...setCameraPosition(position) {// 获取相机位置参数const data = cameraPos[position];const viewport = this.renderingEngine.getViewport(idVolume);// 设置相机位置参数viewport.setCamera({viewUp: data.viewUp,viewPlaneNormal: data.viewPlaneNormal});viewport.resetCamera();}
}

3. 调用流程

1) 修改Toolbar3D.vue

• 添加操作元素el-select
• 绑定变量currentCameraPos
• 监听currentCameraPos变化，发送changeCameraPos事件

<script setup name="Toolbar3D">
const cameraPos = [{name:"前视(A)", value: "A"},{name:"后视(P)", value: "P"},{name:"左视(L)", value: "L"},{name:"右视(R)", value: "R"},{name:"俯视(S)", value: "S"},{name:"仰视(I)", value: "I"},
];
const currentCameraPos = ref("A");
watch(currentCameraPos, (newValue) => {emit("action", { name: "changeCameraPos", value: newValue });
});
</script>
<template>...<div class="toolbar-row"><div class="pre-label">Camera:</div><el-select v-model="currentCameraPos" placeholder="Select Camera Position" style="width: 200px"><el-option v-for="item in cameraPos" :key="item.value" :label="item.name" :value="item.value" /></el-select></div>
</template>

2) 修改View3d.vue

在OnToolbarAction中添加事件响应

async function OnToolbarAction(action) {...case "changeCameraPos":displayArea.value.setCameraPosition(action.value);break;
}

3) 修改DisplayerArea3D.vue

添加并导出函数setCameraPosition

const setCameraPosition = position => {theMPR.setCameraPosition(position);
};defineExpose({...setCameraPosition
});

二、所有视图复位

1.复位流程说明

VR视图：

1. 图像加载成功后保存相机初始参数
2. 相机参数设置为初始参数
3. 设置默认preset

切片视图：
3. 调用viewport.resetCamera()
4. 设置默认窗宽窗位

修改mprvr.js，在loadImages函数中保存相机初始参数。增加resetCamera函数

const initVolumeCamera = {viewUp: [],viewPlaneNormal: [],position: [],focalPoint: [],viewAngle: 0,parallelScale: 1
};export default class MPR {...async loadImages(imageIds) {...this.renderingEngine.renderViewports(viewportIds);const viewport = this.renderingEngine.getViewport(idVolume);await setVolumesForViewports(this.renderingEngine, [{ volumeId }], [idVolume]).then(() => {viewport.setProperties({preset: "CT-Coronary-Arteries-2"});// 保存相机初始参数const camera = viewport.getCamera();initVolumeCamera.viewUp = camera.viewUp;initVolumeCamera.viewPlaneNormal = camera.viewPlaneNormal;initVolumeCamera.position = camera.position;initVolumeCamera.focalPoint = camera.focalPoint;initVolumeCamera.viewAngle = camera.viewAngle;initVolumeCamera.parallelScale = camera.parallelScale;});...}resetCamera() {if (!this.loaded) return;viewportIds.forEach(viewportId => {const viewport = this.renderingEngine.getViewport(viewportId);if (viewport) {if (viewportId === idVolume) { // VR视图// 设置默认presetviewport.setProperties({preset: "CT-Coronary-Arteries-2"});// 设置初始相机参数const camera = viewport.getCamera();camera.viewUp = initVolumeCamera.viewUp;camera.viewPlaneNormal = initVolumeCamera.viewPlaneNormal;camera.position = initVolumeCamera.position;camera.focalPoint = initVolumeCamera.focalPoint;camera.viewAngle = initVolumeCamera.viewAngle;camera.parallelScale = initVolumeCamera.parallelScale;viewport.setCamera(camera);} else { // 切片视图viewport.resetCamera();viewport.render();}}});}
}

2. 调用流程

1) Toolbar3D中添加"复位"按钮，发送reset事件

2) View3d.vue中响应reset事件，调用DispalerArea3D中的reset函数

3) DisplayerArea3D中添加并导出reset函数，增加setDefaultWindow函数

// defWW, defWL在load函数中保存了默认窗值
const setDefaultWindow = () => {theMPR.setWindow(defWW.value, defWL.value);
};const reset = () => {theMPR.resetCamera();setDefaultWindow();
};defineExpose({...reset 
});

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总结

1.讲解VR视图六个正向视图的相机参数是如何设置的
2.VR视图与切片视图复位