I use to color maps by scrap altitude. 

Lately I noticed Therion color gradient starts from 0 m altitude to maximum cave altitude. Because caves don't reach 0 m almost all color range is unused and most scraps are colored with similar colors. If I remember correctly some time ago Therion used all color range because color gradient extended from minimum cave altitude (not 0 m) to maximum. 

Am I missing something? Is there a way to use all available colors?

Thanks,

Marco