We present a novel deep architecture and a training strategy to learn a local feature pipeline from scratch, using collections of images without the need for human supervision. To do so we exploit depth and relative camera pose cues to create a virtual target that the network should achieve on one image, provided the outputs of the network for the other image. While this process is inherently non-differentiable, we show that we can optimize the network in a two-branch setup by confining it to one branch, while preserving differentiability in the other. We train our method on both indoor and outdoor datasets, with depth data from 3D sensors for the former, and depth estimates from an off-the-shelf Structure-from-Motion solution for the latter. Our models outperform the state of the art on sparse feature matching on both datasets, while running at 60+ fps for QVGA images.


Is Arizona's Horseshoe Bend too popular for its own good?
Horseshoe Bend once was a scenic overlook known only to locals. But social media has made it a tourism star, requiring changes to keep up with crowds.
HORSESHOE BEND — In simpler times (before social media), Horseshoe Bend was a quiet yet spectacular stop along a lonely stretch of highway in northern Arizona.
Visitors would wander in from U.S. 89, just south of Page, Arizona, either because they'd heard of the dramatic bend in the Colorado River from locals, or noticed the small sign pointing the way and reacted quickly enough to make the sharp turn.
They would take a sandy path to an overlook where the land dropped away steeply to reveal a canvas only nature could paint — an emerald river hundreds of feet below, tracing a graceful arc at the bottom of sharp-edged cliffs.
A few hundred people might stop each day during the summer road-trip season. In winter, maybe just a few dozen.
But those languid days are long gone, lost in the exhaust fumes of the tour buses, party vans and SUVs that choke an area never meant to hold so much glass and steel. Each day they disgorge thousands of visitors, many from China and Germany and France and Japan.
Last year, roughly 1.5 million people made the half-mile hike to see the way the Colorado River crafted an artful canyon. Officials for Glen Canyon National Recreation Area, of which Horseshoe Bend is a part, estimate that 2 million people will visit in 2018. Precise numbers aren't available because there's no entrance station.
It wasn't always that way. Page City Manager Crystal Dyches remembers heading to Horseshoe Bend when she needed to get away, enjoying a view uncluttered by people.
No longer. Horseshoe Bend is one of the most popular destinations in northwestern Arizona, so much so that parking restrictions were recently put in place for safety's sake.
Large tour buses, which often arrive several at a time during the busy summer months, are no longer allowed to park. They can only drop off and pick up passengers, according to restrictions that went into effect in June.
Visitors can no longer park along U.S. 89, a dangerous but common practice when the lot fills up. Drivers who can't find a spot in the lot must return at another time.
Restrictions or no, the same scenes play out each day at the attraction almost too popular for its own good.
Cars circle the lot for parking spots. Tourist fall into lockstep along the sandy trail over the ridge, some pausing at the top to catch their breath.
The trail descends the ridge. At the bottom, sand yields to smooth, rippling stone that flows toward the canyon of the Colorado, disappearing like a stream over a waterfall.
With each step forward, the canyon reveals a little more of itself. Many visitors stop 10 or 20 feet short of the ledge, satisfied with an obscured but safe view, standing on tiptoe to glimpse the green water below.
Others approach the sheer cliff cautiously, assuming a prone position to poke their heads and shoulders over the abyss, then rolling on their back to take a selfie.
A daring few sit on the edge, legs dangling for dramatic effect.
Below, a boat powering upriver marred the polished green surface, the craft trailed by the thin white scratch of a wake that served as a reminder this was not a painting.
Visitors wander along the unprotected rim. There no trails leading down, just a sharp edge with solid ground on one side and empty air on the other.
Accidents are rare, but they do happen. On May 6, 2018, a Phoenix man fell 800 feet to his death. Zachary Wallace, 33, slipped over the edge, his brother told National Park Service rangers. In July 2010, a Greek tourist fell to his death.
Summer heat also poses a danger. Visitors ill-prepared for the short hike — some making the trek with little or no water — wind up calling 911, according to Pamela Rice, assistant superintendent for Glen Canyon National Recreation Area.
These are among the reasons park officials approved a $750,000 project to build a viewing deck with safety railing, as well as gently sloping, ADA-compatible trails that skirt the high point of the ridge. The new path is slightly longer but easier to navigate.
The deck opened June 19, providing a safer way to view the canyon, though visitors are free to explore the ledge as they please.
The opening of the new trail was postponed to January 2019 as construction was suspended due to the summer heat. Work will recommence in September.
A second phase of improvements starts later this year when the City of Page begins construction of a new parking lot.
The project, now in the design process, will include 310 parking stalls for cars and buses, with a potential of up to 130 additional stalls, according to Kim Johnson the city's community development director. She said work is expected to be completed by spring 2019.
The plans also include the installation of three booths to facilitate fee collection, Johnson said. The amount has yet to be determined, though officials are considering $10 for cars, $50 per small or mid-size bus and $100 per large bus.
Revenue is expected to be split between between the National Park Service and Page, and much of it used to maintain and improve the area.
Once the parking lot and entrance booths are finished, officials will turn their attention to a spacious visitor center designed to blend into the surroundings, according to Dyches, teh city manager. That work could start in the latter half of 2019 if the project is included in Page's 2019-2020 budget, she said.
Page officials also are in touch with the Arizona Department of Transportation in an effort to widen U.S. 89 at the Horseshoe Bend turnoff.
The addition of a left-turn lane likely would reduce accidents caused by visitors who slow or stop to make the turn into Horseshoe Bend, Dyches said.
Details: Horseshoe Bend is 3 miles south of Page on U.S. 89. Horseshoe Bend Tours offers a shuttle that runs hourly 8 a.m.-4 p.m. $30, $20 for ages 6-11. 435-275-4594, horseshoebendtours.com.


text:
if ENV['COVERAGE']
  require 'simplecov'
  require 'coveralls'

  SimpleCov.start { add_filter '/spec/' }
  SimpleCov.merge_timeout 300
end

require 'bundler/setup'

require 'i18n'

require 'vagrant-lxc'

Dir[File.dirname(__FILE__) + "/support/**/*.rb"].each { |f| require f }

RSpec.configure do |config|
  config.treat_symbols_as_metadata_keys_with_true_values = true
  config.run_all_when_everything_filtered = true
  config.filter_run :focus

  # Run specs in random order to surface order dependencies. If you find an
  # order dependency and want to debug it, you can fix the order by providing
  # the seed, which is printed after each run.
  #     --seed 1234
  config.order = 'random'

  config.mock_with :rspec do |c|
    c.yield_receiver_to_any_instance_implementation_blocks = true
  end
  config.expect_with :rspec do |c|
    c.syntax = :expect
  end
  config.raise_errors_for_deprecations!
end

redpajama_set_name: RedPajamaGithub


text:
tod news
Massachusetts Governor taps well-known transit advocate for transportation secretary
Gabrielle Gurley | Commonweath Magazine
Stephanie Pollack May know more about the MBTA than anyone alive. She's been a dogged advocate for transit expansion. She opposed the repeal of gas tax indexing, believing the state needs a steady stream of new revenue to meet infrastructure needs. And she has lots of solid ideas for dealing with the state's transportation problems. The catch is most of them cost money.
How does a transportation advocate with stellar policy bona fides but limited public sector experience work with a Republican governor who has sworn off new taxes and fees?
We're about to find out. Pollack, one of the Bay State's foremost transportation experts, was tapped by Gov. Charlie Baker on Tuesday to become the first woman to lead the state Department of Transportation.
"Stephanie is one of the top transportation minds in Massachusetts," said former transportation secretary Richard Davey who headed up MassDOT from 2011 to 2014.
Michael Wider, the outgoing president of the Massachusetts Taxpayers Foundation, recently told CommonWealth that ideally Baker needed a transportation visionary to helm one of the state's most complex sectors.
In selecting Pollack, Baker is going with the vision thing. Pollack, associate director of Northeastern University's Dukakis Center for Urban and Regional Policy, has been a fervent advocate of the need to invest in state transportation assets, while being well-versed in the sector's deep financial problems. "Massachusetts has run up all its credit cards in the transportation area," Pollack told CommonWealth in 2008.
Although she lacks direct public sector experience, Pollack has credibility on Beacon Hill as one of the go-to experts for lawmakers on transportation policy issues, particularly in the most recent debates over new revenues.
She also should work well within MassDOT. "Stephanie is the type of person who can bring a calming influence on the management side and let the day-to-day operations staff do their jobs," said Davey.
Pollack has spent ten years at the Dukakis Center, where she advised Patrick administration officials and worked on several important studies of state and federal transportation policy.
"She was helpful to us in the implementation of both transportation reform and MassDOT's [environmental responsibility and sustainability initiative]," said Jeffrey Mullan, who headed MassDOT from 2009 to 2011. "Her passion for the field and her fundamental understanding of how it is that we arrived at the point we are now at will serve her well in her new role."
Pollack has one of the most challenging missions of any member of the Baker cabinet. Former governor Deval Patrick went through five transportation secretaries. State residents, who are perhaps more intimately acquainted with transportation than any other state government department, are vocal about its shortcomings.
Pollack comes into a sector that has been leeching revenues after the repeals of gas tax indexing and the tech tax.
She also has to handle the problems of the MBTA, which will be under new pressures to improve performance and spruce up trains, buses, and stationsas the 2024 Summer Olympics selection looms.
"[MBTA] is definitely more about putting out fires than expanding service. It's really getting hard to use the system," Pollack told CommonWealth in 2013.
But she has some cards to play. Both the Red and Orange lines will have new rail cars in the next several years. She can look forward to steering other projects that she once advocated for like the Green Line extension."You need a steady hand at the top to make sure that the bureaucracy is moving those projects forward," said Davey.
Reforms, such as the establishment of a project selection advisory councilto look at specific transportation proposals recommendation may, according to Davey, take some of politics out of projects and give lawmakers a sense of what projects are feasible in the current fiscal climate.
One thing is certain: Since former governor Patrick and state lawmakers recently tussled over new transportation revenues, there is going to be little appetite to revisit the issue.
"Often people believe that 50 cents should buy you a dollar's worth of projects in Massachusetts and it's just not possible," Davey said. "The [latest] reform and revenue [debate], while it didn't deliver all of the major capital projects people wanted, it has delivered some fiscal stability in the short term to MassDOT and the T. So there really is an opportunity for someone like Stephanie to help think about what the next decade, two decades look like. Frankly, that may be the way to sell a further revenue conversation down the line."
© 2015 TR Advisors | 77 Franklin Street, 9th Floor, Boston, MA 02110 | Asset Management | Brokerage | Consulting | Resources | About TRA | Contact Us | Site Map

redpajama_set_name: RedPajamaCommonCrawl


text:
Q: Why is this considered ordered sampling (Casella Berger)? I'm working on example 1.18 in Casella & Berger and I'm confused by the solution.
The problem states:

If n balls are placed at random into n cells, find the probability that exactly one cell remains empty.

In the solutions manual, it states that there are $n^n$ total ways to place $n$ balls into $n$ cells. This implies the sampling method is ordered with replacement. I agree that the $n$ cells are sampled with replacement. But, why is it considered ordered?
My logic:
Let's pretend there are 3 cells. If I place a ball into {1,1,2}, {1,2,1}, or {2,1,1}, in the end I have 2 balls in cell 1, and 1 ball in cell 2. The ordering does not matter.
What am I misunderstanding here?

A: Since this problem is self study (and the solution is given in the text) I'll sketch out how I would approach the problem and let you fill in the gaps. I think it's easiest to approach by counting the valid orderings (like Michael suggested in the comments) and dividing by the total possible orderings.
The problem becomes easier when you think about what must be true if only one cell is empty. Here's a hint: if precisely one cell is empty, can a cell have 3 balls in it?
Solution hidden below:

 No. If precisely 1 cell is empty, then precisely 1 other cell has 2 balls in it and the rest have 1 ball. If one cell had 3 balls then at least 2 cells must be empty.

Given that, it's straightforward to count the number of valid events and total events.
How many ways can we choose the 2 cells which don't have 1 ball in them?

 ${n}\choose{2}$

How many ways can we order the balls and place them into cells?

 $n!$

That gives us our numerator, the total number of possible orderings:

 ${{n}\choose{2}} \cdot n!$

How many ways can I place $n$ balls into $n$ cells? Well the first ball can be placed into $n$ cells, the second into $n$ cells, and so on leading to $n^n$ total possible arrangements of the system. This gives the probability as (number valid)/(total):

 ${{n}\choose{2}}\ n!\ /\ n^n$

redpajama_set_name: RedPajamaStackExchange