最多的3D三角使用极几何比例 [英] Up to scale in 3D triangulation using epipolar geometry

问题描述

我目前工作的一个项目中，我必须估计使用单眼相机检测到的二维兴趣点的三维坐标。

I'm currently working on a project in which I have to estimate 3D coordinates of 2D interest points detected using a monocular camera.

要更precise，我在输入图像序列（校准），它是必需的，接收新的图像时，进行三角左侧之间的点（previous）图像和右当前让3D点。

To be more precise, I have in input an image sequence (calibrated) and it is required, when receiving a new image, to triangulate points between the left (previous) image and the right current one to get 3D points.

要做到这一点，我在下面的步骤：

To do this, I'm following these steps:

1. 在当前图像中提取关键点
2. 当前和previous图像之间建立对应关系
3. 在计算使用RANSAC的基本矩阵E和高点算法
4. 从提取E中的变换矩阵R和平移向量t
5. 通过正交回归计算使用三角测量的三维点

由此产生的三维点是不正确的，当我重新投影他们上的图像。但是，我已阅读，三角测量点被定义为只到一个不确定的比例因子。

The resulting 3D points are not correct when I reproject them on the images. But, I have read that the triangulated points are defined to only up to an indeterminant scale factor.

所以我的问题是： 什么是向上扩展是指在这方面？什么是解决方案，使场景中的世界的真正的3D点坐标系？

So my question is: What does "up to scale" means in this context? And what is the solution to get the real 3D points in the scene's world coordinate frame?

我会很感激您的帮助！

推荐答案

您可能有错误或估计不好本质矩阵。未知比例系数不负责你看到重建的错误。无论全球范围内，投射到图像对的结果，从精彩的比赛和一个有效的本质矩阵估计3D点应该是一致的。

You are likely to have a bug or a poorly estimated essential matrix. The unknown scale factor cannot be responsible for the reconstruction errors you see. Regardless of global scale, the result of projecting onto the image pair a 3d point estimated from good matches and with a valid essential matrix should be consistent.

的高达秤在这方面的意思是说，即使有校准相机，估计本质矩阵的标准方法产生同样的结果，如果你有一个中一切都是​​由较大或较小的更换场景相同的量。您可以通过在场景识别已知的物理尺寸的对象，并强加你的计算机三维重建的规模相匹配的事后删除此混淆，例如。

The meaning of "up to scale" in this context is that, even with calibrated cameras, the standard method of estimating the essential matrix yields the same result if you replace your scene with one in which everything is larger or smaller by the same amount. You can remove this ambiguity after the fact, for example by identifying in the scene an object of known physical size, and imposing that your computed 3d reconstruction matches that size.

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