I wish to add imagery to my drawing as a backdrop to my design in AutoCAD
With an Autodesk subscription, you have access to load Bing maps into AutoCAD. This provides for you to load a road map or aerial photography. The difficulty is how you deal with the latitude and longitude coordinate system as you are most likely using Ordnance Survey mapping, which is based around its own coordinate system.
The first thing to determine is the location of your mapping. There are a number of good online tools for converting an Ordnance Survey, twelve figure map coordinate into a latitude and longitude (latlong), and there is also a useful ‘location sensor’ within KeyOSC. On the utilities ribbon panel, there is a pair of items. The function you need is the ‘Latitude/Longitude sensor’. This gives a latlong coordinate as you move your mouse around your drawing.
You should find an obvious reference point such as the corner of a significant building. Once you have identified a suitable significant feature, you can click on it, and KeyOSC will print to the command line the latlong at the selected point. Press enter to finish the command and then the F2 key so that you can copy the printed coordinate.
Move mouse. Latitude and longitude is shown on the status bar (press [ENTER] to exit):
Lat long at selected point (OS Grid x: 430811.4002, y: 265009.1037 is 52.282320 N and 1.549774 W.
Next, make sure you have the drawing units set correctly to metres using the UNITS command and, if you are in AutoCAD Civil 3D, that the AECDWGUNITSSETUP command also has the units set to metres.
Now you are ready to start the GEOGRAPHICLOCATION command. Enter the copied latlong into the ‘Address’ bar at the top of the dialog.
You can zoom in to the significant feature, the building corner of other reference point you selected, using your wheel mouse and, once you have identified the location, right-click on the feature. This gives a menu choice to ‘Drop Marker Here’.
Then click ‘Next’ and, from the GIS Coordinate system list, select GB_ORD1.
Note - This is some way down the list and you will have to scroll down to find it. Then click ‘Next’ again.
The next step is to select the building corner in your drawing and lastly set the rotation for the mapping (which will always be the default value). Note, depending on how you have coordinate and angular measurement set-up, this may be 90 degrees. This is perfectly normal if you have angular measurement configured so that North is straight up the page, with angles measured increasing in the clockwise direction.
You may just find that the aerial imagery doesn’t line up perfectly. To make small adjustments, you can ‘Reorient Marker’. This is a repeat of the last two steps of the process above, and may seem at first to be counterintuitive. It works a little like the PAN command, using the current location of the marker as the first of a ‘move’ for the imagery. You also need to confirm the default rotation. You can repeat this until you get it right.