projections投影图projectionn.投影；投射；规划；发射；凸出物；预测；放映projection programs预测程式projection histogram投影直方图projection perimeter投射式视野计projection character投影特征projection operators射影算子projection zoom lens变焦距镜头projection technique投射技术,投影技术projection direction投影方向projection equipment放映设备projection apparatus投影仪