Create a map image like the ones seen on doom wiki

[Cyborggeffien]

How do people create images of levels like the ones you see on the doom wiki?

Here is an image to show what I'm talking about:

[Gez]

There exist two ways of generating images like this:
1. OMGIFOL's map creation script
2. SLADE 3's "Save map image" button, see tutorial here.