In studying dynamic remodeling of environmental mapping around a mobile robot operated remotely while data measured by the robot range sensor is sent from the robot to the operator, we introduce the Line & Hollow method and the Cell & Hollow method for environmental mapping. Results for the three types of environmental situation clarifies features and effectiveness of our approach. In Line & Hollow method, an isosceles triangle is set based on the range data. The base line is pulled to express obstacle shape and the inside is hollowed out to express vacant space. In Cell & Hollow method, the cell value corresponding to the range data is incremented, and an obstacle is assumed to be exist if the cell value exceeds the ascending threshold. The cell value is decremented on the line between the cell that measured data indicates and the cell located at the sensor, and the obstacle is deleted if the value drops below the descending threshold. We confirmed that environmental mapping for either reflects a dynamic environmental change.