Creating a MapMarker to imitate XML Drawable - Maps V217 Jul 2013 | Maps Xamarin.Android
So from here I have two choices, either create an image with the desired marker, or draw it programatically on a Bitmap Canvas. The first one is easy enough and I will not show that here, it is just a simple image you pop into the drawable folders in your Android project. The latter is way more fun and could be useful to you. The sample will be using Xamarin.Android to demonstrate how it is done there, however, it may be applicable to Java Android.
So first you need to know how big you want to have the marker to be.
In this case I just set it to 60dp, you can experiment with that. Now you have to do the drawing action.
Now that you have your BitmapDescriptor you can set it as an Icon for the map Marker.