Very good point! Yeah, please be advised there's artistic license taken and the Z-axis scale is arbitrary (well, not arbitrary, it's linear but stretched and certainly doesn't start at 0). You're totally right that the difference between the lowest areas and the highest isn't really as exaggerated as it appears. The real delta between lowest and highest is about 2.7x. I'd argue though that a difference between ~$500/sq ft vs $1,200/sq ft is enough of a difference to make the top of the range feel entirely out of reach for anyone living in the bottom of the range, and that's what the sculpture was meant to convey.

Truly, you'd want to pin rent as 25% of income and then have the height be related to where you would need to be on the U.S. income scale as a percentile to be able to afford it.

ie: You've got a $899,000 home sale, that's supposedly a ~$4000/mo rent, which leads towards a "25% rule" of $16,000/mo income => $192,000/yr => which is supposedly 93.9%-ile.

Going from $4000/mo => $5000/mo, it seems like it takes you to 96.8%-ile.

The absolute difference in dollars scales ridiculously high though once you start getting above 90%ile though. Going by percentile practically makes it a logarithmic scale.

> Going by percentile practically makes it a logarithmic scale

In theory as well. Small changes of the log of a variable are approximately equivalent to small percent-changes.

Edit: Though percentile is a little different than percent-change.

My interpretation of it was that a 2.7X delta in price between lowest and highest isn't correlated linearly with affordability. i.e. a house that's twice as expensive per square foot doesn't make it half as affordable. People who already have to leverage themselves extensively to mortgage a property will never afford a property twice as expensive per square foot so it's actually infinitely less affordable, if you see what I mean.

That's the sort of "artistic license" that leads the adherents to the politics of envy to make proclamations about how life is somehow less worth living when you know someone else has more than you. When charitable, people call it hyperbole. At its core, it is simple emotional manipulation. At least you were subtle about it!

This is really nice art and data visualization too.

It's common to scale the elevation of a topographic map to exaggerate features [1], even non-linearly [2]. If you try to 3d print a raised relief globe without exaggeration it is surprisingly flat. If you're buying an expensive classroom globe, the specs talk about the exaggeration [2].

This is a sculpture, so whatever goes, but perhaps the designer looked at the version without exaggeration and noticed that it looked less emphatic.

I also think, as data visualization, this sculpture nicely shows the extreme change in price which occurs over small spatial distances. That's really important, and, actually, the tendency to make real estate price heatmaps with models that force continuity and prefer smoothness, like cubic splines, suppresses that aspect of the data. Railroad tracks and some beautification really are sometimes the only thing between million dollar homes and mobile parks.

It would be cool to see this with neighborhood boundaries/names on the mesh.

[1] "A raised-relief map or terrain model is a three-dimensional representation, usually of terrain, materialized as a physical artifact. When representing terrain, the vertical dimension is usually exaggerated by a factor between five and ten; this facilitates the visual recognition of terrain features." https://en.wikipedia.org/wiki/Raised-relief_map

[2] "Raised Relief: Yes. Elevations from 0-3,280 feet are magnified 60 times, higher elevations and ocean floor are exaggerated by 40 times." http://www.1worldglobes.com/1WorldGlobes/classroom_relief_gl...

Very true. So, the question becomes: is this 3D printed chart misleading or is it focused on the relevant data?

I must stress that I'm realize I'm being very analytic about a piece of art. As art and as a statement, I recognize that it is very well done. I just don't have much to say about it other than wondering if it is misleading.

Can the answer be both? If you're trying to use it as a chart to figure out home prices it doesn't provide enough information and it's misleading when it comes to determining the numeric relationship between regions. But if you're using it to get a sense of the impossibility of moving from one of the lower-cost parts of the city to one of the more expensive areas of SF, I think this captures that emotional feeling. I say that as a former SF homeowner who used to live right below the base of that big cliff face going from the Richmond up to Twin Peaks/Noe Valley. Looking at home prices in those areas gives you that feeling of smashing your face against one of those cliff walls.

What are you talking about? The Richmond is not adjacent to Twin Peaks or Noe Valley. It's not even close. There are several neighborhoods in between.

You're right, but I was talking about the steady increase in price as you move from the Inner Richmond southeast toward Noe Valley on the sculpture. That cuts through the Haight, Cole Valley, Castro, etc. In terms of how I binned the data by hexagons, that's a diagonal progression across 4 adjacent hexagons, moving from an average price of $766/sq ft on the eastern side of the Inner Richmond across all the way up to $1,050 in Noe Valley. In the photos of the sculpture it might be hard to identify how much that rising part of the sculpture is actually moving south, but it is (and can be seen a bit better if you play with the model yourself or watch the animated gif of it rotating).

I feel ya. Thanks for making this and thanks for sharing it!