I have checked the values. For example, I have the following values generated by i.landsat.toar (Reflectance of Landsat-7 ETM+ (method dos4)) for Band 1: Range of data: Range of data: min = 0.01 max = 0.384689793990633 After applying i.topo.corr the values changed to Range of data: min = -252.767458308413 max = 2928.43556843211. I am a begginer user and any support will be welcome.

Hi reima, for Landsat MSS3, Landsat 5 TM and one Landsat OIL it worked fine and I got a really good result. But for Landsat another OLI and for Landsat 7 ETM+ it does not work. I used exactly the same commands. It runs normally without any error, but the result is a "white" image (white square for all bands).