如何进行2D图片绘制 [英] How to perform 2D picture plotting

问题描述

嗨


当我模拟 Kelvin Shipe Wake [ ^ ]我需要绘制结果。



我想要的如下图所示：

https://skydrive.live.com/?cid=31C12AA3E3EE0DCB&id=31C12AA3E3EE0DCB!505 [ ^ ]



我使用的代码是（在每个矩形上）：

Hi
When I simulated a Kelvin Shipe Wake[^] I had a need of plotting the result.

And I wanted something like the picture below:
https://skydrive.live.com/?cid=31C12AA3E3EE0DCB&id=31C12AA3E3EE0DCB!505[^]

The code I used was (on each rectangle):

Public Function ColorGradient(ByVal Value As Single) As Brush
    Dim val As Single
    Dim bt As Byte

    Val = 1 - Math.Abs(Value) * 10 / 3
    If Val() > 1 Then Val = 1
    If Val() < 0 Then Val = 0
    bt = Val() * 255

    If Value > 0 Then
        'Red color
        Return New SolidColorBrush(Color.FromRgb(255, bt, bt))
    ElseIf Value < 0 Then
        'Blue color
        Return New SolidColorBrush(Color.FromRgb(bt, bt, 255))
    Else
        'White color
        Return New SolidColorBrush(Colors.White)
    End If
End Function

这些情节叫做什么？如果我不知道这个名字，我不知道该搜索什么...

（可能你知道任何文章的表现比我粗略的版本好吗？）



编辑：

Kelvin Wake代码如下所示：

What are these kind of plots called? If I dont know the name I dont know what to search for...
(and possibly Do you know any articles that performs better versions than my crude example?)


The Kelvin Wake code looks like this:

Private Function MidPointKelvin(ByVal x As Double, ByVal y As Double)
    Dim m As Double = 80
    Dim h As Double = Math.PI / (2 * m)
    Dim p As Double = 0.001
    Dim pheda, t1, t2, sum, g1, gp1, cg1, sg1, sgp1 As Double
    sum = 0
    For i As Integer = 1 To m
        pheda = -(Math.PI / 2) + (2 * i - 1) * h
        g1 = g0(x, y, pheda)
        gp1 = gp(x, y, pheda)
        cg1 = Math.Sin(gp1 * h)
        sg1 = Math.Sin(g1)
        sgp1 = Math.Sin(gp1 * h)
        t1 = p * 2 * h * cg1
        t2 = 2 * gp1 * cg1 * sgp1
        sum = sum + (t1 + t2) / (p + gp1 ^ 2)
    Next
    Return sum
End Function

Private Function g0(ByVal x As Double, ByVal y As Double, ByVal p As Double) As Double
    Return (x - y * Math.Tan(p)) / Math.Cos(p)
End Function

Private Function gp(ByVal x As Double, ByVal y As Double, ByVal p As Double) As Double
    Return -(1 / Math.Cos(p)) ^ 3 + (1 / Math.Cos(p)) * Math.Tan(p) * (x - y * Math.Tan(p))
End Function

这是一份直接副本：

http://demonstrations.wolfram.com/KelvinShipWavePattern/ [ ^ ]

（点击预览查看代码）

And it is a direct copy from :
http://demonstrations.wolfram.com/KelvinShipWavePattern/[^]
(Click preview to see the code)

推荐答案

也许这是视错觉（可能不是，见下面看，但看起来像大图片的外部计数器是弯曲的，这不适合马赫锥体描述的物理模型。



请参阅：

http://en.wikipedia.org/wiki/Cherenkov_radiation [ ^ ]。



是的，船上波浪的数学与切伦科夫的辐射相同;我之所以引用这个页面只是因为目前缺少Mach''s cone上的英文维基百科页面。还有一个动画图片，我在相关的英文维基百科页面上也找不到：



http://upload.wikimedia.org/wikipedia/commons/8/87/Cherenkov_radiation-animation.gif [ ^ ]（点击查看动画）。 />


您引用的第一个图像为 https： //skydrive.live.com/?cid=31C12AA3E3EE0DCB&id=31C12AA3E3EE0DCB！505 5.5 [ ^ ]当然不适合物理模型。如果你真的想描绘船上的波浪，你使用你所展示的波浪图片是不正确的。



如果你模仿别的东西，请解释。

-SA

Maybe this is optical illusion (probably not, see below), but it looks like outer counters of a big pictures are curved, which would not fit a physical model which is described by the Mach cone.

Please see:
http://en.wikipedia.org/wiki/Cherenkov_radiation[^].

Yes, the mathematics of the wave from a boat is identical to the Cherenkov''s radiation; I''ve referenced this page just because the English Wikipedia page on Mach''s cone is presently missing. There is also an animated picture, which I also could not find on related English Wikipedia pages:

http://upload.wikimedia.org/wikipedia/commons/8/87/Cherenkov_radiation-animation.gif[^] (click to see the animation).

Your very first image you referenced as https://skydrive.live.com/?cid=31C12AA3E3EE0DCB&id=31C12AA3E3EE0DCB!505[^] certainly does not fit the physical model. If you really want to depict the wave from a boat, you the use of the wave picture you show would not be correct.

If you model something else, please explain.

—SA

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