"If this SGO LOGO is 3,000 people .... Can this be 26,000 people?"
Various objections were raised to this comparison. Among which:
- The scale/camera distance is different
- The SG50 people are using umbrellas
- The venue is different (Bishan Park vs Hong Lim Park)
Yet, if one opens an umbrella, one can accommodate at most one other person underneath (if you blow up the SG50 photo you will see that everyone is using standard one-person umbrellas [not the huge ones]).
So I decided to make some estimates.
Let us make the simplifying assumption that Hong Lim Park is a rectangle.
This inflates the estimate a bit by including some road, Telok Ayer Hong Lim Green Community Centre and Kreta Ayer NPP.
Rotating the Google Maps image (Google Maps no longer allows you to rotate the maps grr), we find that Hong Lim Park is 338 px by 181 px. It is also a trapezium, but assuming it is a rectangle it more-or-less cancels out.
Following the onscreen scale, we note that 83 pixels is 50m in length. So Hong Lim Park is about 204m by 109m, for an area of 22,236 square metres.
According to Wired, in a packed crowd each person takes up 2.5 square feet (~0.25 square metres). Other estimates I've seen are similar.
So if the whole area of Hong Lim Park were packed with people, we would have 88,944 people in there, which is even bigger than the supposed event attendance of 26,000.
However, what we see in the original photo (or others) is not a packed crowd.
Returning to Wired:
In a loose crowd, where people are at an arms length of each other, figure about 10 square feet of space per person.
In the photo (and others), we can see that people are on average from one to half an arms length from each other, so that gives us a crowd of 22,000 to 44,000 people.
Yet, note that this is assuming the *whole* of Hong Lim Park was filled. In reality it looks like maybe a third to a half of the total area was filled with the crowd.
So there can't have been more than 22,000 people there, and that is being generous. A lower bound for event attendance would be about 7,000.
Alternatively, measuring the size of the lightup it seems to take up about 1/6 of Hong Lim Park, which when combined with the packed crowd calculations gives 15,000 at most.
I heard that event attendance for Pink Dot was estimated by clocking people walking in and out, so there would've been a lot of double and triple-or-more-counting.