Validação de ortomosaicos e modelos digitais de terreno utilizando fotografias obtidas com câmera digital não métrica acoplada a um VANT

Resumo

generated by aerial photography program using aerial photographs taken with an Unmanned Aerial Vehicle (UAV) in the city of Goiás - GO, Brazil. The fl ight plan was drawn up in the program E-mo-tion. The camera used was a Canon IXUS 220 HS, with spatial resolution of 12 megapixel, CMOS sensor equipped with type 1/2.3 “ (4000 x 3000 pixels), 1.54 μm sensor element, and calibrated focal length of 4.382 mm, coupled to the UAV Swinglet CAM model. The fl ight was performed at approximately 716 meters above the ground with side and longitudinal overlapping of 40% and 70%, respectively, with a Ground Sampling Distance (GSD) of 25 cm. The photogrammetric block had 9 tracks, with 62 photos, covering 889.39 ha. From those photos we generated two Orthomosaics and two Digital Surface Model (DSM) with Pix4Dmapper software. The fi rst orthomosaic and DSM were generated using direct georeferencing without ground point supporting (i.e., without geodesic GPS survey). The second orthomosaic and DSM were generated using, in addition to direct georeferencing, eight pre-signaled GPS points on the ground. The bias was analyzed by Student’s test (t) and accuracy by the probability of the chi-square (), following the standards set by the Federal Decree 89.817/84. The fi rst orthomosaic, without ground point supporting, was classifi ed as Class A on the scale 1/2.500, while the second orthomosaic, generated with ground point supporting, was classifi ed as Class A on the scale of 1/1.125. Thus, the fi rst orthomosaic presented a planialtimetric trend. Although the program has generated the DSM, DTM was evaluated due all the control points implanted on the ground. The DTM evaluated with and without ground point supporting presented vertical displacement trend. It was evident the needing of ground point supporting for making orthomosaics and DTM with UAV.

Descrição

Palavras-chave

Padrão de exatidão cartográfica, Coordenadas tridimensionais, Alvos pré-sinalizados, Drones, Standard cartographic, Accuracy, Three-dimensional coordinates, Pre-fl agged targets

Citação

ALVES JÚNIOR, Leomar Rufino et al. Validação de ortomosaicos e modelos digitais de terreno utilizando fotografias obtidas com câmera digital não métrica acoplada a um VANT. Revista Brasileira de Cartografia, Rio de Janeiro, v. 67, n. 7, p. 1453-1466, nov./dez. 2015.