更新林相图的计算机辅助方法

常规编制与更新林相图的方法要求昂贵的光学机械纠正仪器、较高的操作技术和成本。文章提出一种利用计算机辅助纠正航空象片更新林相图的方法,可以降低成本,提高成图效率。为了实现这种方法,首先根据航空摄影理论分析,推导出适合编程的航空纠正数字化线性模型和算法。该模型要求在底图和航片上有四对控制点坐标,求算纠正参数。采用数字化仪测定这些坐标,求解参数,然后根据该线性模型对航片上编图要素的数字化坐标进行非共面变换,进而更新林相图。为完成这一过程需要四个程序模块和处理流程。使用这种方法更新林相图既能保证精度要求,又具有操作简单的优点。

THE METHOD WITH THE AID OF COMPUTER FOR RENEWING FOREST TYPE MAP

The traditional method for developing and renewing forest type map requires expensive optics machinery equipment and high level of operation technique and cost. The paper proposes a method of correcting aerial photo with computer and digitizer for renewing forest type map, which would decrease the cost and enhance effect of mapping. For peformance of the method, the method and algorithm of correcting aerial photo is developed based on theory analysis of photogrmmetry, which facilitates progamming. It is necessary for application of the model that coordinates of Four control points on both of base map and aerial photo must be known and parameters of the model are solved by them. The paper suggests these coordinates are measured by using digitizer, and the coordinates on photo to be mapped are converted into the map coordinate system; it also disucusses four programs and process formats for implementing the method. At last, it points out that the method is not only able to meet the accuracy, but has the advantage of simple operation for renewing forest type map.