Darker Textures than Photoreal

[hugopiugo 1]

Hi,

I used 1024x1024px textures to create a photoreal polygon to get the highest quality as possible near the runway.
Underneath I've created a photoreal with Sbuilder, with the resample process.
Everything is great, except when the sunrise or sunset time approaches. The 1024px textures get much darker than the resampled.
Here's an example:

The green area was made with Gmax, with 1024x1024 tiles. The red area is satellite image I got with Sbuilder.

Why do they have different colors sometimes during the day?

 

Thank you very much in advance