Question

The Normalized Digital Surface Model is generally calculated as:

• A. DSM + DTM
• B. DSM $-$ DTM
• C. DTM $-$ DSM
• D. DSM/DTM

Hint:

Remember: \[ \boxed{ \text{DSM} = \text{Ground} + \text{Objects} } \] Therefore, \[ \boxed{ \text{DSM}-\text{DTM} = \text{Object Height} } \]

Answer 1

The Correct Option is B

Concept: A Normalized Digital Surface Model (nDSM) represents the height of objects above the ground surface. It is obtained by subtracting the ground elevation (DTM) from the surface elevation (DSM).

Step 1: Understand the models.
• DSM (Digital Surface Model): Includes buildings, trees and terrain.
• DTM (Digital Terrain Model): Represents only the bare earth.

Step 2: Compute nDSM. \[ \boxed{ \text{nDSM}=\text{DSM}-\text{DTM} } \] This gives the height of above-ground objects. Hence, \[ \boxed{\text{Normalized Digital Surface Model = DSM - DTM}.} \] Therefore, the correct option is \[ \boxed{(B).} \]