Today (10/31/2013) IBGE releases, on its website, orthorectified and mosaicked images of Tocantins, obtained through the AVNIR-2 sensor of the ALOS satellite.

The orthorectified images and the sheets (at 1:100 000) of the ortho-mosaics are available in GeoTIFF format on IBGE webpage, through the link 
ftp://geoftp.ibge.gov.br/imagens_orbitais/

For further informationon on  this product, see ftp://geoftp.ibge.gov.br/imagens_orbitais/ortoimagens/Descritivo_Projeto_BC100_TO_situacao2013_outubro_v1.pdf

Collection integrates project BC 100

The image collection released by IBGE is part of the project "Cartographic Base 1: 100 000" (BC 100), which was elaborated to give society access to orthorectified images, ortho-mosaics and image-maps of several Federation Units. The idea is to meet the demands for updated information, compatible with the 1:100.000 scale.

The orthorectified images undergo a correction process in relation to the several geometric distortions, caused by different factors, such as the angle from which the image is taken, the relief, the Earth's curvature and rotation. The mosaicking process gathers a set of orthorectified images from AVNIR-2 which are cut and assembled to cover all the area equivalent to the topographic sheet dimension. The mosaics were radiometrically enhanced in order to convey an easier visualization and interpretation of the elements.

The collection released today comes with orthorectified images and ortho-mosaics thoroughly covering the territory of Tocantins - which corresponds to 127 sheets of systematic terrestrial mapping.

Satellite images with 10 m spatial resolution

The AVNIR-2 sensor produces images with a spatial resolution of 10 meters, in four spectral bands, corresponding to blue, green, red and near infrared. The images used were obtained between the years 2006 and 2010, 91% of them were concentrated between 2009 and 2010.