Votorantin Metais Níquel S.A’s mineral research Project, carried out in the City of Montes Claros de Goiás − GO − Brazil, revealed that the future mine shall produce 25 thousand tons of nickel per year.
The economic feasibility studies that Votorantim Metais is conducting should be completed in 2009, so the mine can become operational in 2012. It is investing R$ 558 million in this project alone, which will generate 420 direct jobs and 2 thousand indirect jobs.
ESTEIO S.A. was hired to conduct the mapping that will be the basis for Votorantin Metais Níquel S.A.’s engineering projects. An accurate planialtimetric survey was carried out, making use of airborne LASER and photogrammetric aerial camera, in the region of Montes Claros de Goiás, adding up to 567.00 Km² of contours of elevation mapping and 26.00 Km² of digital orthophotomaps.
Laser Survey
LEICA Geosystems’ ALS 50 II (Airborne Laser Scanner) equipment is a planialtimetric survey system that uses a LASER beams emitter / receiver associated to a GPS receiver and an Inertial System, these devices being managed and integrated by a central computer. It has a swath angle of up to 75º and it can fly in altitudes up to 6,000 meters.
For this project, we used 2,300 meters of altitude and opening angle of 26º, resulting in 1.2 meter of average spacing between the points in the Digital Surface model.
Flight Steps
The flight for aerial photographs in the 1:8.000 scale was made up of 5 surveyed strips at an average flight height of 1,200 meters. This originated the orthophotomaps in the 1:2.000 scale.
The LASER flight was made up of 25 strips, performed at 2,300 meters, originating contour lines of 1 x 1 m to cover the 567,00 km² of the project.
Digital Surface Model (DSM) and Digital Terrain Model (DTM)
The data gathered through LASER survey, in addition to having (x,y,z) information, also have an intensity value of the signal reflected. These values are used in composition images of hypsometry/intensity for planimetric presentation of LASER information.
The multiple pulses characteristic of the LASER system enables the ranking of the various returns of the LASER signal, allowing the separation of the points that are above the surface (DSM) from the points that compose the terrain (DTM). After this processing, the LASER data are ready for the generation of the digital surface and terrain models.
Contour Lines
DTM points already filtered and depurated will form the LASER points cloud. These points will be treated with TIN (Triangle Irregular Network) algorithms to form triangles and, consequently, create contour lines.
Digital Orthophotomaps
The aerial photographs were orthorectified by means of the obtaining of images with geometric precision equivalent to the restituted charts.
Contour lines were projected, meter by meter, over the images to generate final products in the 1:2.000 scale.