How to draw Curves in GIS Development
This article mainly introduces how to draw curves in GIS development, which has certain reference value. Interested friends can refer to it. I hope you will have a lot of gains after reading this article. Let Xiaobian take you to understand it together.
In map development, curves are sometimes used. In general, map APIs provide methods for drawing curves, or provide corresponding legends.
The following is a brief introduction to how to draw a Bezier curve according to the position of points on the map.
A Bézier curve, also known as a Bezier curve or Bézier curve, is a mathematical curve applied to two-dimensional graphics applications. General vector graphics software through it to accurately draw curves, Betz curve by segments and nodes, nodes are draggable fulcrum, segments like elastic rubber band, we see in the drawing tool pen tool is to do this vector curve. Bezier curve is a very important parametric curve in computer graphics. There are also Bezier curve tools in some mature bitmap software, such as PhotoShop. -- From Wikipedia
When drawing on a map, when drawing in a small range, the latitude and longitude coordinates or plane coordinate system are similar. When drawing in a large range, try to convert the latitude and longitude into length units (such as metric system), because the calculation is based on the corresponding distance.
Bessel's algorithm, you can search on github to a lot, according to their own development language to choose one of them can be.
Simple js example: github.com/Aaaaaaaty/bezierMaker.js
When drawing a curve, at least 3 points are needed to draw it. When passing in the coordinates of more than 3 points, the curve effect can be generated.
This algorithm itself has a lot of open source. When drawing on a map, it only involves latitude and longitude, which is a radian unit. There will be corresponding concerns when drawing it. Understand the principle and directly input the coordinates of the distance type to draw the above curve effect.
Note: When drawing curves on a three-dimensional spherical map, the height value should also be passed in as a factor, otherwise the effect of drawing will not be achieved.
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