So I think the overall quality of the maps could be greatly improved by pimping a bit what's actually outside the cities. Putting some trees and forests, using gradients on "non-built" ground to make it feel like it's not 100% flat, and maybe dividing the farmed areas into actual plot of lands (this last one might come hard to make look good, but it's worth thinking about, and maybe prototyping).
Here's a couple of Ideas
Is it really a detrimental botteneck tho? As an end user I would be more interested in a good end result rather than performance (if i where to choose). It's not like I need to generate 100's of maps in quick succession.
That is a pretty sick move to make it 3d :P
You have a good point about the unresponsiveness, but stating that in clear text to the user would be a quick fix for that tho. I mean, nobody likes to wait, but if you feel you know why you are waiting, most people are a lot more OK with it. Might be moot if the 3d method is that much better at drawing.
Hey, totally unrelated to this, but do you plan on adding rivers? Either through the cities or around the outskirts? With most cities in the real world springing up around them, I would think it a pretty good addition to this excellent generator.
Im not sure if other people have mentioned this idea, but I think visualizing terrain and slopes could be handled similarly to topographic maps. Instead of using a line where there is a increase of height you could have that each elevation be one solid shade of a the background color. The lower the terrain is to sea level, the darker the shade, and lighter it gets the higher it gets. an additional idea would be to have a customization option for how many elevations changes there are on a map. example: 10 shades or 5, etc. Random would simply pick a number between 1-20.
That would make it quite complex though. You dont want a city where there is a lot of places with a big altitude diffrence.
for example it would be okay to have 1 place in your city where there is a lvl10 and a lvl1 next to eachother, but haveing 6 of those places would make for a pretty odd city