I’ve been working on a terrain texture detailing shader to overcome low quality issues when using low resolution ortho photos. Actually, the ortho photos which I use have a resolution between 2 and 25 m/pixel. To achieve a higher quality, the shader applies the detail noise based on the following rules:
Original texel == green? → apply grass texture
Original texel == gray? → apply pebbles texture
else → apply a generic natural texture (a mix between rocks and other stuff)
The high detail noise is additionally mixed with a low detail noise to get rid of repeating patterns. The colors and noise textures can be changed based on the geotypical environment (urban, rural, desert, etc.)
There is still room for improvement, e.g. water surfaces are not yet considered.
It is very important, that the shader does not affect the overall impression when viewed from higher altitudes:
Very nice! Beautiful!
I was going to say fade out the effect with distance or something but the “after” high altitude shot actually looks better to my eyes.