Are you referring to the background images, or the NavMesh?
A new NavMesh can be constructed using Unity shapes such as cubes, baking the NavMesh, and then hiding the original shapes. A tutorial on creating 3D NavMeshes can be found here.
2.5D games of the type covered by the tutorial typically rely on either photographs (which the tutorial uses), or pre-renderered backgrounds made in external 3D software such as Blender.
When importing backgrounds into a 2.5D game, it's important to have a means of matching up Unity's 3D camera / floor elements in a way that matches the backgrounds.
When using pre-rendered 3D backgrounds, this is fairly simple: so long as you have the original 3D file used to render the image, you can measure the dimensions, FOV etc used to produce it.
When working with photographs, you'll need to take measurements of the environment you're shooting in, as well as the physical camera settings, so that you can match things up again when you're working in Unity.
Comments
Are you referring to the background images, or the NavMesh?
A new NavMesh can be constructed using Unity shapes such as cubes, baking the NavMesh, and then hiding the original shapes. A tutorial on creating 3D NavMeshes can be found here.
2.5D games of the type covered by the tutorial typically rely on either photographs (which the tutorial uses), or pre-renderered backgrounds made in external 3D software such as Blender.
When importing backgrounds into a 2.5D game, it's important to have a means of matching up Unity's 3D camera / floor elements in a way that matches the backgrounds.
When using pre-rendered 3D backgrounds, this is fairly simple: so long as you have the original 3D file used to render the image, you can measure the dimensions, FOV etc used to produce it.
When working with photographs, you'll need to take measurements of the environment you're shooting in, as well as the physical camera settings, so that you can match things up again when you're working in Unity.