基于STL模型的船舶吃水转换功能实现

提出一种基于船舶外壳STL模型及S-H多边形剪裁算法的船舶吃水转化方法。根据船舶设计部门提供的船舶STL模型，用船舶六面水尺所在的平面切割STL模型，得到各个水尺的封闭多边形。根据船舶当前的载况计算出船舶的首尾吃水及横倾角，确定倾斜水线面的方程。基于S-H多边形剪裁算法，将各个水尺的封闭多边形和水线面求交即可计算出六面吃水。以6.4万吨散货船“Spring Cosmos”和25万吨矿砂船“Shandong Ren He”为例进行实例计算，和船舶设计软件NAPA计算值相比，绝对误差都在1 cm左右，证明上述方法的正确性。实验表明：算法计算精度较高，通用性好，适用于船舶任意载况，具有一定的工程实用价值。

Ship draft conversion based STL model

A ship draft conversion method is proposed based on ship STL model and S-H polygon clipping algorithm. Ship's shell STL model is provided by the ship design department. By using of the planes which is determined by six draft marks to clip the STL model, closed polygons of each draft mark is obtained. According to the current loading condition to calculate the heel angle and fore-and-aft draft, the equation of the inclined waterline is calculated. Six drafts is calculated through the polygon and water plane intersection by using of S-H clipping algorithm. 64 000 DWT bulk carrier Spring Cos-mos and 250 000 DWT ore carrier Shandong Ren He were taken as examples to calculate six draft, compared with the result calculated by ship design software NAPA, all the absolute errors are about 1 cm, method mentioned above is proved. Experi-ments showed that algorithm's calculation precision is higher and can applicable to use in any ship loading condition. The method has a certain practical application value and versatility.