Light-obstructing objects is the term Design Master Electrical uses to describe anything that will block light during the outdoor photometric calculations. In this tutorial, the only light-obstructing object is the building itself. Design Master Electrical's light-obstructing objects can also be used to model overhangs, trees, etc.
To define a light-obstructing object in the shape of the building, first go to
DM Electrical 
Point-by-Point Photometrics Draw Light-Obstructing Shape
The Insert Light Obstructing Shape dialog will appear. Set the specifications for light obstructing solid to match those shown below. (The specifications that you will need to change are highlighted in yellow in the screen shot below. They will not be highlighted on your dialog box.) Once the specifications match, press OK.
Design Master Electrical will take you to the drawing and prompt you to indicate the first point of the photometric solid. Click on each corner of the building, beginning in one corner and working your way around the building. Once you have clicked on every corner of the building, you may press ENTER to close the object. Your drawing should match the one shown below.
Next, we will check the outdoor photometric information attached to light fixture S.