How to make a Minimap with Tilemap

I'm creating an isometric game that uses Tilemap renderers to create 3d walls/floors in an isometric view by manipulating their rotation. I have a floor that is using a tilemap renderer that uses sprites as tiles.

I have a minimap icon system working where important objects have an additional sprite icon in a layer visible only to the MinimapIcon Camera. I also want this for the floor but I don't want to copy the floor's tilemap renderer and change the sprite tile to my minimap sprite tile because I have a lot of floor.

Is there a way for my minimap camera to see my floor and output my minimap sprite tile instead of the floor tile that it actually is? Maybe a stencil shader? Or an X-ray shader of some sort?

 

Can you just use the built-in Unity layers and make the minimap camera only see layers you want, whereas the main camera sees all the layers? (or however)

 

Hi, thanks for the reply.

I mentioned in my second paragraph that I am indeed doing that. But I would like to avoid having to duplicate my entire floor simply for the purpose of the minimap, so I was asking if there was a way to do it without duplicating it. Would this extra floor layer have any impact on performance if it only appears on one layer?