Matlab：极坐标灰度图 [英] Matlab: polar coordinates grey scale plot

问题描述

编辑：我决定将这个问题分成两部分，因为它实际上是两个问题：1。如何在MATLAB（这个问题）和

因为MATLAB将图像存储为矩阵，极坐标我不完全匹配矩阵的'bins'。因此，我们目前使用插值算法将极坐标放入方阵中。但是，这非常慢。我看到两种方法可以解决这个问题：

1. 让MATLAB直接将数据点绘制为极坐标。


2. 计算一次如何从起始矩阵转换到结束矩阵，让MATLAB通过矩阵乘法来做到这一点。

一些基本信息：

输入矩阵大小：512×960

当前输出矩阵大小：1024×1024

解决方案

问题解决了（除了一个小缺陷），部分原因是KM Shihab Uddin指出了我正确的方向。不幸的是，使用冲浪意味着不断地在图中绘制图像，这也很慢。

因此，对于每个X和Y组合，我在X和Y值中都有单独的矩阵和灰度值（在一个名为C的矩阵中）。

我发现pcolor只是从顶部观察冲浪。所以我使用以下代码绘制我的图表。

 冲浪（X，Y，C * 255）
查看（[0,0,500]）
  

然而，这给了我一个完全黑色的图像。这是因为在我的情况下，surf（和pcolor）在径向上创建了960个网格线。解决方案是使用：

  surf（X，Y，img2 * 255，'EdgeColor'，'none'）
查看（[0,0,500]）
  

现在我有一个近乎完美的形象，就像我有之前。只有在我的960个径向线中，一个是白色的，所以我仍然必须解决这个问题。但是，我觉得这是函数surf的技术细节，回答这部分并不属于这个问题。

生成的图片

edit: I decided to split this question into two parts, because it were really two questions: 1. how to make a polar surface plot in MATLAB (this question) and 2. how to put fit polar data points into a coarse (and non-polar) matrix

I have a matrix that contains certain grey values (values between zero and one). These points are stored in a rectangular matrix, but really the data points are acquired by rotating the detector. This means that I actually have polar coordinates (I know the polar coordinates for every single pixel in my starting matrix).

I want to make a polar plot of the data points. I have the example of this below.

Because MATLAB stores images as matrices, the polar coordinates I have do not exactly match the 'bins' of the matrix. Therefore, we currently use an interpolation algorithm to put the polar coordinates into a square matrix. However, this is extremely slow. I see two methods to solve this issue:

1. let MATLAB directly plot the data points as polar.
2. calculate once how to convert from the start matrix to the end matrix and let MATLAB do this through matrix multiplication.

Some basic information:

Input matrix size: 512×960

Current output matrix size: 1024×1024

解决方案

The question was solved (apart from a minor flaw), partially because K.M. Shihab Uddin pointed me in the right direction. Unfortunately, using surf means continuously really plotting the image in a figure, and this is slow as well.

So I have X and Y values both in separate matrices and greyscale values (in a matrix called C) for every X and Y combination.

I found out that pcolor is just surf with a viewpoint from the top. So I used the following code to plot my graph.

surf(X,Y,C*255)
view([0,0,500])

However, this gave me a completely black image. This is because surf (and pcolor) create 960 grid lines radially in my case. The solution is to use:

surf(X,Y,img2*255,'EdgeColor','none')
view([0,0,500])

Now I have an almost perfect image, like I had before. Only, of my 960 radial lines, one is left white, so I still have to solve that. However, I feel this is a technical detail of the function surf, and answering this part does not belong in this question.

The resulting image

这篇关于Matlab：极坐标灰度图的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！