Aiming at the problems that the measuring accuracy of traditional digital level is affected by measurement distance and field of view and the fixed code element can hardly ensure the measuring accuracy both at long and short distances, to further improve the measuring accuracy of digital level, the paper puts forward an encoding and decoding scheme. Taking advantage of the isotropic nature of circle, it uses circular bar codes to substitute the traditional bar code for preparation, uses area array CCD to obtain two-dimensional encoded images, applies different encoding systems at different distances, uses the maximum similarity matching algorithm in rough measurement and makes resolution based on proportion in accurate measurement. Comparative experiments show that this method has a higher resolution, higher measuring accuracy, and can realize high-accuracy and quick leveling. Measuring range of the device is 2-100 m and the absolute error of single point measurement is less than ±0.2 mm.%针对传统的数字水准仪测量精度受到测量距离和视场的制约,固定的码元难以兼容远近测量的精度等问题,为进一步提高数字水准仪的测量精度,该文提出一种编解码方案,利用圆的各向同性性质,以圆形码代替传统条形码进行编制,并且采用面阵CCD获取二维编码图像,同时在远近不同距离采用不同进制编码,在解码粗测时应用最大相似匹配算法,精测时应用比例求解.对比实验证明,该编解码方法分辨率较高,测量更加准确,实现高精度、快速水准测量.测量范围为2~100 m,单点测量绝对误差小于±0.2 mm.
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