LiDAR Altimetry Data Evaluation According to the Brazilian Map Accuracy Standards
ISBN 978-85-88783-11-9
Authors
1Ferreira, F.R.; 2Cintra, J.P.
1POLYTECHNIC SCHOOL OF THE UNIVERSITY OF SAO PAULO Email: flavia.re@hotmail.com
2POLYTECHNIC SCHOOL OF THE UNIVERSITY OF SAO PAULO Email: jpcintra@usp.br
Abstract
LiDAR (Light Detection And Ranging) has been consolidated as a mapping technology, contributing to the geographic information science. An altimetry accuracy test of LiDAR points was conducted; these were obtained by profiling an urbanized area in the city of Sao Paulo, Brazil. The density of the points was 1.5 points per m². For the accuracy test, a 1: 1,000 - scale mapping was used as the reference product. The contours of the reference mapping, which was 1 m of equidistance, were converted into eleven polygons (areas). Points classified as “ground” by LiDAR were selected in each of these areas in order to verify the difference between the value of the altitude of each point and the value of the average elevation of the area comprising the point. These differences were subjected to a similar test to the accuracy test according to the altimetry accuracy standard for digital cartographic products of the new Brazilian map accuracy standards. In the eleven data sets tested, seven met class B for 1: 10,000 scale, one met class B for 1: 25,000 scale, and the other three, respectively, met class B, C and D for scale 1: 5,000. By visual inspection, the set that obtained poorest classification was one narrow range in the Pinheiros River ring road, in which landslides have occurred. In summary, we developed a new methodology for altimetric quality control, and found that this product is suitable for mapping, taking into account the purpose, the scale of the mapping and the accuracy required for concrete application.