Industrial desirability bug?
I think I have spotted a bug, or at least an interesting discrepancy, in the way that industrial desirability is calculated. I find it hard to believe I'm the first to notice this, but couldn't find any mention of it when I tried a forum search, so apologies if it's old news.
One of the desirability factors for all types of industry is slope. At least one advisor dialog suggests that industries prefer flat terrain, and this is what the Prima Strategy Guide says about it too. At this point you might be able to guess what the bug/discrepancy is... It's actually the other way around! Industries prefer building on slopes - the steeper the better.
I happened to notice it yesterday when I was taking a look at the desirability factors in the developer exemplars. Each industrial developer exemplar has the Slope Effect property, described as "How much slope is a factor in desirability". In every case it is set to 0,0,50,10 - suggesting that the steeper the slope, the greater the desirability boost. At first I thought it must actually be using a "flatness" variable rather than slope, but it turns out that desirability really does increase with slope.
Here are two industrial buildings in different parts of the Big City Tutorial tile, which I had been using to test a few things:
An I-M building on relatively flat terrain...
...and an I-HT building on more sloped terrain
From the query.txt files for these I got the following information:
I-M on flat terrain
...
| Slope: 1.2
...
| Desirability equation for I manufacturing
| desirability = base value: 47
| + land value effect, f(value: 1): 0
| + slope effect, f(value: 1.6): 0 ... I-HT on sloped terrain ... | Slope: 9.1 ... | Desirability equation for I high tech
| desirability = base value: -94
| + land value effect, f(value: 204): 6
| + slope effect, f(value: 16.9): 3 ... I'm not sure why there are two different numbers for slope, but it's clear that the more sloped terrain the I-HT is built on is having a small positive effect on desirability, while the flat terrain where the I-M is has zero effect. I tried a few different options for fixing this. Here's I-HT desirability in the same tile with the original slope effect of 0,0,50,10: Here I've reversed the relationship to 0,10,50,0: And here I've tried restricting the range of slopes that give a positive effect, and adding a negative effect to steeper slopes (0,10,10,0,20,-10): The overall effect on desirability is fairly small because slope has much less weight than other factors such as crime and pollution. Reversing the relationship to 0,10,50,0 increases desirability slightly over the whole tile, except on the steep undeveloped terrain the other side of the river (note the green square on the steepest ground in the first image that disappears in the second). Giving steeper slopes a negative effect reduces desirability in the more hilly terrain to the west and across the river. So although it's not really a big deal, it probably does reduce I-HT desirability a bit in cities on relatively flat tiles, in a way that I can't believe was intended.
| desirability = base value: 47
| + land value effect, f(value: 1): 0
| + slope effect, f(value: 1.6): 0 ... I-HT on sloped terrain ... | Slope: 9.1 ... | Desirability equation for I high tech
| desirability = base value: -94
| + land value effect, f(value: 204): 6
| + slope effect, f(value: 16.9): 3 ... I'm not sure why there are two different numbers for slope, but it's clear that the more sloped terrain the I-HT is built on is having a small positive effect on desirability, while the flat terrain where the I-M is has zero effect. I tried a few different options for fixing this. Here's I-HT desirability in the same tile with the original slope effect of 0,0,50,10: Here I've reversed the relationship to 0,10,50,0: And here I've tried restricting the range of slopes that give a positive effect, and adding a negative effect to steeper slopes (0,10,10,0,20,-10): The overall effect on desirability is fairly small because slope has much less weight than other factors such as crime and pollution. Reversing the relationship to 0,10,50,0 increases desirability slightly over the whole tile, except on the steep undeveloped terrain the other side of the river (note the green square on the steepest ground in the first image that disappears in the second). Giving steeper slopes a negative effect reduces desirability in the more hilly terrain to the west and across the river. So although it's not really a big deal, it probably does reduce I-HT desirability a bit in cities on relatively flat tiles, in a way that I can't believe was intended.
