如何使用Java在四边形内找到像素点？ [英] How do i find pixels points inside quadrilateral using Java?

问题描述

我做了一些图像处理，我有四边形4点的坐标。
（类似于梯形）
如何获得其中所有像素的坐标？我顺便使用Java。
谢谢！

Im doing some image processing and I have the coordinates of the 4 points of a quadrilateral. (something like a trapezium) How can i get the coordinates of all the pixels inside it? I'm using Java by the way. Thanks!

推荐答案

您需要扫描线多边形填充。

You need scanline polygon filling.

这是关于这个主题的快速PDF讲座：

Here's a quick PDF lecture on the subject:

http://www.cs.binghamton.edu/~reckert/460/lect11_2009-areafill-transformations.pdf

这是一个网页示例，其中包含一些示例C代码和基本概念的良好说明：

Here's a web page example with some sample C code and a good illustration of the basic idea:

http://alienryderflex.com/polygon_fill/

这是简短形式。将四边形线划分为左侧和右侧的线。对于每个恒定Y坐标行，找出左边的交叉点;弄清楚右线的交叉点;两个交叉点之间的那一行上的所有像素都在你的梯形内。

Here's the short form. Divide your quadrilateral lines into those that are on the left, and on the right. For each constant-Y-coordinate row, figure out the crossing point for the left line; figure out the crossing point for the right line; all pixels on that row between the two crossing points are inside of your trapezoid.

仅仅通过历史，这种事情最初（可能仍然是）已完成用于在软件中渲染3D场景。我认为它当时有一个不同的名字，但我不记得了。但是，您实际上不必绘制像素;无论你是否绘制它，算法都会给你像素。

Just by way of history, this sort of thing was originally (and probably still is) done for rendering 3d scenes in software. I think it had a different name back then, but I can't remember it. However, you don't actually have to draw the pixels; the algorithm will give you the pixels whether you draw them or not.

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