Class

Type of relief

Ds

R1

Very low relief

Ds < 10 m

R2

Low relief

10 < Ds< 25 m

R3

Fairly low relief

25 < Ds< 50 m

R4

Moderate relief

50 < Ds< 100 m

R5

Fairly strong relief

100 < Ds< 250 m

R6

Strong relief

250 < Ds< 500 m

R7

Very strong relief

500 m < Ds