I have raw data with x, y, z coordinates before work and after work. I have to calculate mass volume between two of them. I have converted two files into tin. I have used surface difference (3D Analyst) tool in Arcscene. Output file contain column Volume in m3. Is this correct steps of calculation ?
Yes, these are the fundamental steps to achieve your goal.
The outputs according to ESRI can be read as;
Volume—The volume of space between the input and reference surface that is bounded by the polygon. Volume will always be 0 for areas where the two surfaces are the same.
SArea—The surface area of the input surface that is bounded by the polygon.
Code—A numeric value that describes the spatial relationship of the surface to the reference plane. -1 indicates the surface is below the reference plane, 0 indicates the surface is the same as the reference plane, and 1 indicates the surface is above the reference plane.
Ensure you data is projected. Ensure your x,y,z units and projection are all use the same base-level unit (say meters).
Before and after does not matter so much as all you will get is inverted numbers so just switch the sign. Technically you have before and after the wrong way around as I assume before is your reference layer. It is all in the ArcGIS help link.
in_surface = The terrain or TIN surface whose relative displacement is being evaluated from the reference surface.
in_reference_surface = The terrain or TIN surface that will be used as the baseline for determining the relative displacement of the input surface.