Making a topographic map in Illustrator can be done in a few simple steps. First, create a new document with a desired map size (in inches or centimeters) and a resolution of 300 ppi. Next, select the Base Map layer and click on the Add Layer Mask button (in the Layers panel). This will create a new layer entitled Base Map Mask.
Select the Brush tool and set the brush size to 100% (or use the keyboard shortcut [B]). Paint over the entire map with the black brush to create a dark background.
Now, make sure the Base Map Mask layer is still selected and click on the Edit Mask button (in the Layers panel). This will open the Layer Mask Options dialog box. In this dialog box, you will need to select the Select All tool and click on the Clear button to remove the background from the map.
Next, click on the Add Source button and select the Layer with the Base Map Mask layer. This will add the map data from the Base Map layer to the selection, making it easy to fill in the details.
To fill in the details, first click on the Add Point button and add points to the map by clicking and dragging. Next, add lines by clicking and dragging from one point to another.
To add a curve to a line, click and drag from a point on the line to another point on the line. You can also use the Pen tool to create lines and curves.
To add features to the map, click on the Add Polygon button and add polygons by clicking and dragging. You can also use the Ellipse tool to create elliptical shapes.
Finally, to add text to the map, click on the Add Text button and type in the desired text.
When you are finished, you can Save the map as desired.