To help facilitate the placement of drainage-system objects, SWMM can utilize an image as a backdrop behind a project’s study area map. This image is typically a site map of some kind with known dimensions. Any bitmap image file (BMP extension), JPEG image file (JPG or JPEG extension) can be used as a backdrop. These images would typically come from a CAD or GIS drawing of the site or perhaps from an electronically published or scanned topographic or street map.
To add the background image, right click on the empty space on the Schematic view to open context menu. Navigate to Background -> Change Background.
In the pop-up window, navigate to and double click on the background image for undeveloped site at “…\backgound\undeveloped site.jpg”. The background image will be added to the Schematic view. Scroll the mouse wheel to zoom in/out the image until it is properly displayed on the Schematic view.