Surveying precision comparison between UAV,s surveying without ground control points, RTK, PPK compared to conventional GPS in forestry plans

Precision surveying of plantations is important for forest management. But on the other hand, terrestrial area calculation of plantations has problems such as topography, presence of herbaceous, woody intrusive species, relatively low accuracy of conventional GPS in forestry plans, the cost and time of use of DGPS. UAVs have plenty of advantages, such as time and space flexibility in surveying with precise accuracy in centimeter level.

In this research, a drone was used without ground control points, (RTK) system or (PPK) for surveying, and its accuracy was compared to conventional GPS in forestry. The UAV that used was a quadcopter with a spatial resolution of 2/5 centimeters. In order to compare the precision, 7 sites 0/5, 1, 1/5, 2, 2/5, 3 and 4 hectares were used. GPS tracking was done using point and track method. UAV, s flight conducted at heights of 50 and 75 m, and a surveying with theodolite was used as a precision alignment index.

The results of this study showed that surveying using conventional GPS in forestry is based on point method is more accurate than track method, and UAV surveying with no ground control points or (RTK) system or (PPK) is not more accurate than the conventional GPS used in forestry and with increasing flight altitude, its error increases with a nearly constant trend, but by applying the correction coefficient obtained from the ground index, the precision of the UAV surveying is more accurate than the GPS, and the error will be less than one percent decrease.

Considering that in Iran, this technique has not yet entered the studies of preparation and implementation of forestry plans and monitoring of afforestation and their surveying, the results of this study can be effective in the implementation of forestry plans.