1∶20万桐柏—信阳区域地球化学调查基本图件编制

A DISCUSSION ON THE MAP COMPILATION ELEMENTS IN1∶200000 TONGBAI-XINYANG REGIONAL GEOCHEMICAL SURVEY

桐柏—信阳一带区域地球化学调查是全国区域化探扫面的一部分。编图中涉及19和20投影带及4个1∶20万图幅的拼接,制图中存在不少技术难题。为了避免2个投影带产生的裂隙坐标不统一,将20带数据转换到19带,然后在高斯—克吕格座标表中查取座标自然值,并计算座标通用值后进行座标展绘,取得了较好的制图效果。

The TongbaiXinyang regional geochemical survey is a component part of the nationwide regional geochemical survey. The map compilation involves the collage of No.19 zone and No.20 zone as well as four 1∶200000 map sheets, and hence there exist quite a few difficult technical problems in mapmaking. In order to avoid the fissure coordinate inconsistency between the two projection zones, the authors converted the data of No.20 zone to No.10 zone, looked up the natural coordinate values in the GaussKruger coordinate table, and calculated the general coordinate values. On such a basis, the coordinate plotting was performed. The mapmaking result seems quite satisfactory.