Rio Negro in the Amazon, LiDAR satellite image. The Rio Negro is one of the largest tributary rivers of the Amazon. This area, just north-west of Manaus, the capital of the Brazilian state of Amazonas, is around 50 kilometres across. LiDAR combines optical and laser imaging to produce digital elevation maps (DEMs), with differences in elevation shown by the colour-coding of the image. Image data obtained by the radar and optical sensors on the Advanced Land Observation Satellite (ALOS) of the Japan Aerospace Exploration Agency (JAXA).