How can I author objects with perspective that fit into a tile-based map but span multiple tiles?

Question

I'm creating a tilemap city and trying to figure out the most efficient way to create unique building scenes. The trick is, I need to maintain a sort of 2D, almost-top-down perspective, which is hard to do with buildings or large objects that span multiple tiles.

I've tried doing three buildings at a time, and mixing and matching the base layer and colors, like this:

This creates a weird overlapping effect, and also doesn't seem that efficient from a production standpoint. But it was the best way to have shadows appear correctly on the neighboring buildings.

I'm wondering if modular buildings would be the way to go? That way I can mix and match any set of buildings together as tiles:

I guess I would have to risk some perspective and shadowing to get the buildings to align correctly.

What sort of authoring process could I use to allow me to create a variety of buildings (or other objects) that maintain this perspective while spanning multiple tiles worth of screen space? Would you recommend creating blank buildings, and then affixing art overlays as necessary to make the buildings unique? Or should they be directly part of the building tile (for example, create a separate tileset of buildings signs and colorings)?

Answer 1

I found an efficient way to build a city fast (or whatever you're trying to build) is definitely to go modular, and make indexed fittings for your buildings. For example:

Single buildings, referenced as A, B, C, etc...

Signs, skins, etc. associated to each:

Now you can mix and match to create a dynamic city quickly

Of the approaches I've tried, this works best.

Answer 2

I think what you are looking for is a form of parallel projection.

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Answer 3

I think I found the best way to do it with the least amount of tiles...

All you need is 6 distinct tiles, composed of polygons:

Then you can create whichever building sizes you want from just these tiles:

And to resolve issue of fitting signs, textures, etc... just take the same approach! :)