Container Survey Data

Container Survey with Drone PIX4D

The video on the left was created using Pix4D, another aerial mapping software with a couplle of extra features. Personally I feel there is no direct winner in terms of end result, one out performs the other in different areas. For this purpose, I wanted to creat a "fly through" of the 3D modelled buidling site

I am listing some of the acronyms used in our work and had to stop to think about whether to list these together or separately, since I am not a pro by any stretch, but I will, for the benefit of those less knowledgeable than I am but who would like to grasp the concept

  • DEM: Digital Elevation Model
  • DSM: Digital Surface Model
  • DTM: Digital Terrain Model

DEM is a subset of DTM and the most fundamental component of DTM.

In practice, these terms (DTM, DEM, DHM, and DTEM) are often assumed to be synonymous and indeed this is often the case. But sometimes they actually refer to different products. That is, there may be slight differences between these terms. Li (1990) has made a comparative analysis of these differences as follows:

Ground: “the solid surface of the earth”; “a solid base or foundation”; “a surface of the earth”; “bottom of the sea”; etc.

Height: “measurement from base to top”; “elevation above the ground or recognized level, especially that of the sea”; “distance upwards”; etc.

Elevation: “height above a given level, especially that of sea”; “height above the horizon”; etc.

Terrain: “tract of country considered with regarded to its natural features, etc.”; “an extent of ground, region, territory”; etc.

Below is a slide image of  a Mosaic, DTM and DSM

Whats the difference?

In my experience, DEM is most of the time used as a generic term for DSMs and DTMs. The image on the left from Wikipedia depicts the differences between DSMs and DTMs well:

DSM = (earth) surface including objects on it

DTM = (earth) surface without any objects