The Piauí nickel reserve is located at Brejo Seco, in the city of Capitão Gervásio de Oliveira, southeast of the State of Piauí, about 50 km away from the city of São João do Piauí and 530 km from Teresina, Capital of the State.
São João do Piauí is located at west, it is the main city of this micro region and, more at south, at about 80 km, the city of São Raimundo Nonato is located, where the National Park Serra da Capivara is located
The agreement VALE / ESTEIO, according to a terminology defined by VALE, intended to perform “Aerial LASER Topographic survey, needed for pre-feasibility studied of Piauí Nickel Project”.
The aerial photogrammetry has appeared as a very appropriate (and effective) methodology in capturing information to support projects in general for the mining field, and with information obtained through photogrammetry in this contract, VALE will have conditions to quickly and accurately define the best positioning of roads that lead to the mine, as well as a better outline for transmission lines. In addition, it will be able to perform terrain relief studies that might help in a macro view of cuts and landfills, taking into account the specific LASER survey results.
As initial activity for this service, ESTEIO performed a colored aerial photogrammetric coverage using LEICA ADS40 digital sensor.
The aerial photogrammetric coverage was performed taking into account the following parameters:
As a result, approximately 900 km² of area were mapped, distributed in the cities of São João do Piauí, Campo Alegre do Fidalgo, Capitão Gervásio Oliveira and Dom Inocêncio, in the State of Piauí.
With the purpose of making the existing products compatible, ESTEIO performed a confirmation of the existing landmarks coordinates based on the documentation provided by VALE.
Basic support, supplementary support, monument location, GPS measurement and geometric leveling implementation activities were developed.
LASER Profiling
To meet the altimetric data collection requirements, ESTEIO has used, for the Piauí Nickel Project, the LASER Profiling technology using the LEICA ALS50 equipment.
Following the example of the photo flight, data from LASER flight were submitted to a preliminary verification, with the purpose to confirm the quality of the information.
After the preliminary verification of the flight quality, the standard inspection was performed, quoting as main details, observing the following:
With LASER survey data processed, a LAS binary file was obtained with information from all pulses. These data are converted into ASCII files with xyz extension.
Having the ASCII files with ENHi coordinates as information source, we had the LASER signal return, and it was possible to generate composition images.
The composition image, a hypsometric image merged with an intensity image, allows viewing the altitude and highlighting the region’s details, in this specific case we were able to highlight with high quality the region’s vegetation and hydrography.
The composition image was chosen by VALE as final product for delivery, so hypsometric and intensity images were used only to generate composition images (see model next).
Based on LASER data, contour lines with 1 meter interval were also delivered.
Already filtered and cleared DTM data formed the LASER points cloud referring to the terrain. These points, treated as TIN (Triangle Irregular Network) algorithms, are inserted in the process to form triangles and consequently create contour lines.
With the purpose to validate LASER activities, altimetric control points were performed in the Field, in addition to GPS surveys for LASER profiling flight base.
In order to prove the quality of the DTM generated, 152 points distributed along the area were compared. The service was executed observing the quality and reliability, and within topographic tolerances according contract specifications.
Products Generates
LASER Profiling and aerial photogrammetric coverage results enabled the confection of the following cartographic products: