August 2, 2026

The QGIS program - Topo maps, part 2 - markers

In part 1 I explored a variety of sources for maps and learned about georeferencing. I next want to learn how to "clip" a map to a long/lat rectangle.
But first something else.

A layer with markers

What I ultimately will have is two layers. One with geology and the other with geography. I also want to have a third layer. It may act as a sort of scratchpad, or it may be more permanent and hold a collection of markers to points of interest.

I use Layer -- Create Layer -- New Shapefile layer.
I give it the name Points and set the geometry type to point.
I leave the CRS at EPSG:4326, but we will see about that.
I move it to the top of the layer stack.
I click the "pen" icon on the top toolbar, then a few icons to the right from it is a "add point feature" icon. Now I click on the map, it adds a point marker and brings up a dialog asking me to name the point. The name does not appear on the map.

I need to select the "hand" icon to get back to the ability to pan and zoom the map.
Now I can right click on the "Points" layer, select Styles and edit symbol, and then make the marker bigger, or a different color, or a different shape.
When I click the visibility checkbox in the layers list, the symbol comes and goes. When I zoom the map, the symbol stays a constant size -- so it doesn't shrink and vanish when I zoom out, which is good. This is indeed what I want.

Changing the marker

You can get to Layer Properties by double clicking on the "Points" layer, or right click to get a menu and then pick "Properties" from the bottom.

The very top shows "single symbol", but you have other choices. Below that is a hierarchy like diagram. Select "Simple Marker" and everything below changes. The top line below is "Symbol layer type". This is a menu and you can select SVG marker and get a bunch of new SVG Images below. Click on any one to select it.

There is an entry field below there (under Dynamic SVG parameters). On my system it displays: 

/usr/share/qgis/svg/amenity/amenity_post_box.svg
Next to this is a box with ... inside. You can click on this to browse your filesystem for some other graphic you created.

Labels

You can label each point. Select "Labels" rather than "Symbology". I found it set to "No Labels" and change it to "Single Labels". It now displays the numeric value I entered when I created the point. It won't lets me enter text for the point ID. More magic could probably be done here using expressions in the Value field:q
Feedback? Questions? Drop me a line!

Tom's Geology Info / tom@mmto.org