Ask HN: Counting # of protestors?

I was at the anti-trump rally in Los Angeles today. The LAPD estimated the crowd size to be 8,000 however that number seemed very low to me. I'm wondering if anyone has some software than can look at footage to estimate crowd size. There are a few shots that capture the majority of the protest today like this: https://instagram.com/p/BMuxQDcjdI4/

Would love to have a hard count of how many ppl were there - not an estimation!

I remember stories about this from the Obama inauguration. IIRC, someone (google?) used areal shots, divide it into segments, assign those segments to different densities, and count the people in samples from all densities.

relevant: http://www.popularmechanics.com/science/a7121/the-curious-sc... and http://www.gkstill.com/Support/crowd-density/CrowdDensity-1....

I checked: about 20 per "row". To get the number of rows, figure out how long the street is and then divide by 2 metres. That's roughly how many people there are.

EDIT:

according to Wikipedia, Wiltshire Blvd is 25km long. I somehow don't think there are that many people in the crowd