Monday, October 15, 2018

On the road

This blog and my Twitter will be less active in the next few days.

I'm on my way to California to have a few weeks off from work and celebrate. My partner completed her masters degree and I finished my PhD, so that's a good enough reason for us to celebrate. See you next month. 

ps. If you really have nothing else better to read in the meantime, have a look at this wonderful  PhD thesis.


image credit: ?, via @CityDescriber (funny bot by Geoff Boing)

Tuesday, October 9, 2018

Friday, October 5, 2018

How Democracies Die

Here is a great seminar by Steven Levitsky talking about his recent book on how democracies die. I cannot emphasize enough the importance of his message in times of strong political polarization like these.

ps. I know. Politics is not really the focus of this blog. However, the coming Brazilian elections (this weekend) are quite depressing and I've found this video very helpful to make sense of the mess we're in. Spoiler alert: the video will not cheer you up.



Thanks Daniel Cardinali for recommending me the video.

Thursday, October 4, 2018

Monday, October 1, 2018

How complete is OpenStreetMap data coverage?

Mikel Maron (MapBox) has addressed this question in 2015 using the CIA World Factbook as a reference. The coverage varies from country to country, as expected, but it's pretty good overall and it only gets better with time. You can check the results for your country here.

More recently, Barrington-Leigh and Millard-Ball addressed the same questions with different methods (ht Ralph Straumann). The authors arrived at a similar conclusion but they also draw some other interesting findings (see the abstract below).  Obs. I'm curious to know why Bolivia stands out from Latin America.

Barrington-Leigh, C., & Millard-Ball, A. (2017). The world’s user-generated road map is more than 80% complete. PloS one, 12(8), e0180698.
Abstract:
OpenStreetMap, a crowdsourced geographic database, provides the only global-level, openly licensed source of geospatial road data, and the only national-level source in many countries. However, researchers, policy makers, and citizens who want to make use of OpenStreetMap (OSM) have little information about whether it can be relied upon in a particular geographic setting. In this paper, we use two complementary, independent methods to assess the completeness of OSM road data in each country in the world. First, we undertake a visual assessment of OSM data against satellite imagery, which provides the input for estimates based on a multilevel regression and poststratification model. Second, we fit sigmoid curves to the cumulative length of contributions, and use them to estimate the saturation level for each country. Both techniques may have more general use for assessing the development and saturation of crowd-sourced data. Our results show that in many places, researchers and policymakers can rely on the completeness of OSM, or will soon be able to do so. We find (i) that globally, OSM is ∼83% complete, and more than 40% of countries—including several in the developing world—have a fully mapped street network; (ii) that well-governed countries with good Internet access tend to be more complete, and that completeness has a U-shaped relationship with population density—both sparsely populated areas and dense cities are the best mapped; and (iii) that existing global datasets used by the World Bank undercount roads by more than 30%.

Completeness of the OSM dataset, by grid cell, January 2016.

credit: Barrington-Leigh & Millard-Ball (2017)


Sunday, September 30, 2018

Quote of the Day - social science

“We live in an era of social science, and have become accustomed to understanding the social world in terms of 'forces,' 'pressures', 'processes', and 'developments'. It is easy to forget that those 'forces' are statistical summaries of the deeds of millions of men and women who act on their beliefs in pursuit of their desires. The habit of submerging the individual into abstractions can lead not only to bad science (it’s not as if the 'social forces' obeyed Newton’s laws) but to dehumanization" (Steven Pinker)

Sunday, September 23, 2018

The day I became a Doctor

I'm very glad  and relieved  to share the news that I became a doctor last week! It might take some time for the university to publish my PhD thesis, so I've decided to make the preprint of the thesis available for download here. I've also created a GitHub repository to share the R code used in the data wrangling, mapping and analysis in the thesis.

My examiners were Nihan Akyelken and Bert van Wee. They were super kind but very challenging, nonetheless. In the end, the PhD viva lasted for 2.5 hours and I was super nervous the whole time. I really enjoyed the viva, though, and I was so surprised when they said I had passed with no corrections that I almost jumped out of my chair. I got this result largely because of my incredibly  demanding  tireless supervisors Tim Schwanen and David Banister, to whom I'm extremely grateful.  All in all, I'm feeling incredibly happy and thankful for the whole journey and the support I received along the away from my family, friends and supervisors. It’s been a truly wonderful and humbling experience.

ps. I still have two papers of the thesis currently under review, but finishing the PhD means that now I'll have much more time to  procrastinate  work on new projects and some others that were put on hold.

photos by my lovely wife, Fabiana - also known as my third supervisor :)

Friday, September 14, 2018

Biographical note: back to the library

Working from the Oxford Bodleian Library and the Radcliffe Camera these days. Getting ready to my PhD defence and the seminar at UCL next week. The blog has been less active these days but I hope to post some good news in the coming days.


Home again



Saturday, September 8, 2018

Presenting a seminar at UCL on Sept 17th: Distributive Justice and Transportation Equity: Inequality in accessibility in Rio

Hi all. I will be in the UK over the next couple of weeks. My PhD defence is on Sept 18th  but I'm too nervous to talk about it these days . Wish me luck !

For those around London, I'll be presenting part of my doctoral research at UCL on Sept 17th (details below). This is part of a new seminar series on Transport and Social Equity jointly organized by the UCL research networks on socially just transport and planning. Thanks Beatriz Mella and Robin Hickman for the kind invitation.

[click on the image to enlarge it]


Thursday, September 6, 2018

Assorted Links

  1. Tokyo has a great public transport system....all things considered

  2. report: Migration Data using Social Media: a European Perspective by Zagheni et al

  3. imagineRio, a searchable atlas that illustrates the social and urban evolution of Rio de Janeiro over the entire history of the city

  4. self recommending: Machine Learning beyond Curve Fitting: An Intro to Causal Inference and do-Calculus, by Ferenc Huszár

  5. Brazil’s National Museum have been lost to fire

  6. The late Waldo Tobler's legendary, seminal, (but unpublished) PhD thesis from 1961 is actually downloadable online. HT Michiel  Meeteren

  7. When should you show percentage changes on a log or linear scale? Great post by Lisa Rost. I should re-read this post every now and then.

  8. Google has launched a search tool for datasets. This is only a beta version but the idea could be really useful in the next years

  9. Calculating driving isochrones considering traffic levels in QGIS (Python script here), by David. If you are more like an ArcGIS person, Riccardo has you covered. BTW, David and Ricardo run the great blog Digital Geography which is also on Twitter.

traffic enhanced isochrones during a in Birmingham
credit: davidribbon



and some isochrones of Chicago

credit: Riccardo

Tuesday, September 4, 2018

Open position at TSU/Oxford for Research Associate in Urban Mobility

This post is just a quick reminder that the Transport Studies Unit (TSU) at Oxford University is recruiting a senior researcher to work on the PEAK Urban project. Ten days left to apply. Job Details here.



This is a really exciting project working with Tim Schwanen (Twitter) in an extremely supportive environment with great colleagues in an excellent research center. I would jump at this opportunity if I could.


Friday, August 31, 2018

New paper out: Transport legacy of mega-events and the redistribution of accessibility to urban destinations


I'm glad to share that the 2nd paper of my thesis is now published. It will remain open access for the next 50 days. Downloaded it here.

This is the 1st empirical paper of my doctoral research. Two other empirical papers are currently under review, but you can read their preprints here and here. My theoretical paper is available here, in case you are looking to have some fun over the weekend.

Pereira, R. H. M. (2018). Transport legacy of mega-events and the redistribution of accessibility to urban destinations. Cities, 81, 45–60. doi:10.1016/j.cities.2018.03.013

Abstract:
Local governments increasingly justify the hosting of mega-events because of their legacy value, assuming that all local residents benefit from those events. Yet, little attention has been paid to the distributive question of who benefits from the transport legacy left by those events. This paper reflects on the delimitation of transport legacies and its social impacts in terms of how such developments can reshape urban accessibility to opportunities. It analyses the transformation in the transport system of Rio de Janeiro (Brazil) in preparation for the 2014 World Cup and the 2016 Olympic Games. That transformation involved substantial expansion in public transport infrastructure, followed by cuts in service levels and a reorganization of many bus lines to streamline the transport system. The paper examines whether those recent changes have increased the number of people from different income levels who could access Olympic sports venues and healthcare facilities by public transport within 15, 30, 60 and 90 min. The analysis uses a before-and-after comparison of Rio's transport network (2014–2017) and a quasi-counterfactual scenario to separate the effects of newly added infrastructure from the reorganization and cuts of transport services. The results show that the infrastructure expansion alone would have increased the number of people who could access the Olympic sports venues, but it would have only marginally improved people's access to healthcare facilities. Nonetheless, the findings indicate that the streamlined bus system have offset the benefits of infrastructure investments in a way that particularly penalizes the poor. The analysis of both the implemented changes to the public transport network and the counterfactual scenario show that the accessibility benefits from the recent cycle of investments and disinvestments in Rio generally accrued to middle- and higher-income groups, reinforcing existing patterns of urban inequality.

Thursday, August 30, 2018

This is how the future of urban transportation will look like

This is true. If this prediction turns out to be wrong in 200 years, I will personally stop writing/editing this blog.

cartoon by André Dahmer

ps. As Ian Philips ‏said: "Excellent to see that in the future there's no compulsory helmet rule for cyclists."

Thursday, August 23, 2018

The geography of Manhattan distorted by travel-times

The figure below was created by Stefan Musch from Gradient Metrics (hat tip Jean Legrand). The figure was created using R and ggplot2 based on travel-time estimates from Google Maps API. There is a bit more info about the creation process in this post and perhaps Stefan will share his code at some point.... please? :)

Echoing the comments of others on Twitter.  The figure does a great job illustrating how it is much harder to cross Manhattan from east to west than from north to south. Finally,  it would be great to see how this shape has changed over the last decades using historical travel time estimates.



credit: Stefan Musch (Gradient Metrics)

Sunday, August 19, 2018

The urban landscape of Hong Kong

Johnny Harris (Vox) has filmed a great series of short-videos that helps us understand the urban landscape of Hong Kong. In one of these videos, Johnny talks about how one of the most unaffordable housing markets in the world is driven by government's land-use regulations. The videos also cover the decline of Hong Kong's neon nightscape and even how feng shui shapes the city skyline. There is also a very informative one about the changing relationship between Hong Kong and China. You can check the list of videos below.



Monday, August 13, 2018

Urban Picture

Barcelona at day and night, by the talented Henry Do (ht Architecture)


Saturday, August 11, 2018

Assorted R Packages for Spatial Analysis

  1. RgeoProfile is an R package for carrying out geographic profiling - a technique derived from criminology that uses the spatial locations of linked crimes to infer the home location (or locations) from which the criminal is operating, by Steve LeComber

  2. rayshader is a package for producing hillshaded maps of elevation matrices with raytracing and spherical texture mapping, by Tyler Mogan.

  3. dodgr: fast calculations of pairwise distances on directed graphs in R, by Mark Padgham

  4. rmapshaper: a simple way to simplify shape files, by Andy Teucher

  5. rpostgis: Linking R with a PostGIS Spatial Database, by David Bucklin and Mathieu Basille

  6. osrmr: a wrapper around the OSRM API, a super fast routing engine for OpenStreetMaps, by Adrian Stämpfli-Schmid

  7. stplanr is a package providing various functions and data access for transport research, by Robin Lovelace. This is the core package underneath The Propensity to Cycle Tool

Monday, August 6, 2018

Tuesday, July 31, 2018

PhD Thesis submitted !

After  4 years, 9 months and 18 days  quite some time, I have finally submitted my thesis to the Examination School of Oxford University. The thesis is entitled “Distributive Justice and Transportation Equity: Inequality in accessibility in Rio de Janeiro”. You can read the abstract below.

Thank you Christine Moore , Homero Paltán and Kevin Wheeler for being there for me, literally !



I will soon share the thesis manuscript. For now, here is the abstract:

   Public transport policies play a key role in shaping the social and spatial structure of cities. These policies influence how easily people can access opportunities, including health and educational services and job positions. The accessibility impacts of transport policies thus have important implications for social inequalities and for the promotion of just and inclusive cities. However, in the transportation literature, there is still little theoretically informed understanding of justice and what it means in the context of transport policies. Moreover, few studies have moved beyond descriptive analyses of accessibility inequalities to evaluate how much those inequalities result from transport policies themselves. This is particularly true in cities from the global South, where accessibility and equity have so far remained marginal concerns in the policy realm. 
   This thesis builds on theories of distributive justice and examines how they can guide the evaluation of transport policies and plans. It points to pathways for rigorous assessment of the accessibility impacts of transport policies and it contributes to current discussions on transportation equity. A justice framework is developed to assess the distributional effects of transport policies. This framework is then applied to evaluate recent transport policies developed in Rio de Janeiro (Brazil) in preparation to host sports mega-events, such as the 2014 FIFA World Cup and the 2016 Olympic Games, which included substantial expansion of the rail and Bus Rapid Transit (BRT) infrastructure. This research presents ex-post analyses of the policies implemented between 2014 and 2017 and ex-ante analysis of an as yet unfinished BRT project. It evaluates how the planned transport legacy of those mega-events impacted accessibility to sports venues, healthcare facilities, public schools and job opportunities for different income groups. 
   The results show that there were overall accessibility benefits from the expansion in transport infrastructure between 2014 and 2017, but these were generally offset by the reduction in bus service levels that followed an economic crisis that hit the city after the Olympics. Quasi-counterfactual analysis suggests that, even if the city had not been hit by the economic crisis, recent transport investments related to mega-events would have led to higher accessibility gains for wealthier groups and increased inequalities in access to opportunities. Results suggest that those investments had, or would have had, greater impact on inequalities of access to jobs than in access to schools and healthcare facilities. The evaluation of the future accessibility impacts of the unfinished BRT corridor, nonetheless, indicates that such project could significantly improve access to job opportunities for a large share of Rio’s population, particularly lower-income groups. Spatial analysis techniques show that the magnitude and statistical significance of these results depend on the spatial scale and travel time threshold selected for cumulative opportunity accessibility analysis. These results demonstrate that the ad-hoc methodological choices of accessibility analysis commonly used in the academic and policy literature can change the conclusions of equity assessments of transportation projects.



Monday, July 23, 2018

Mapping the diversity of population ageing across Europe with a ternary colour scheme

Ilya Kashnitsky and Jonas Schöley have recently published this correspondence in The Lancet where they show a very clever way to visualize the spatial heterogeneity of population age structures using choropleth map with ternary colour scheme. The data wrangling was done in R, and the code to replicate get the data and replicate the figure is available on Github.

Needless to say that, if you're interested in demography, R and data, you should be following the work and twitter accounts of Ilya and Jonas.

click on to image to enlarge it

image credit: Ilya Kashnitsky and Jonas Schöley.

Monday, July 16, 2018

Tuk Tuk Uber

While I was in Dar es Salaam a few weeks ago, Manuel Santana drew my attention to these three-wheeler tuk tuks with "Uber" written at the back (photo below). At first, I thought that was just a marketing strategy or perhaps a funny joke. Little did I knew that those tuk tuks are regular service providers registered with Uber. This is quite telling of Uber's flexibility to adapt to the particularities of each local context (for better or worse).

ps. In case you're wondering, we didn't take Tuk Tuk Uber... We wouldn't be able to squeeze four people in a Tuk Tuk after dinner.



photo credit: Manuel Santana

Sunday, July 15, 2018

Friday, July 6, 2018

Chart of the day: The rich cultural diversity of 200 Years of US immigration

The accumulated history of US immigration visualized as rings in a growing tree trunk. The chart was created by Pedro M. Cruz and John Wihbey using IPUMS data. It's the first time I see migration data depicted in this way and it does a really terrific job drawing attention to composition diversity and population history.

UPDATE: Leah Boustan has just drawn my attention on Twitter for an important shortcoming of this cart. Leah has rightly pointed that:
"This graphic is great for visualizing changes in composition of immigrant flow to US over time but obscures dramatic fluctuations in magnitude. ~1 mil immigrants entered per year in 1910, down to 100k by 1930 — yet the concentric circles makes it seem like entry grows over time"


Thursday, July 5, 2018

TSU/Oxford is recruiting a Research Associate in Urban Mobility

The Transport Studies Unit (TSU / Oxford University) is recruiting a Research Associate in Urban Mobility to work on the PEAK Urban project. If you are interested on questions of transport accessibility, knowledge co-production*, transportation equity and everyday mobilities, you should take a closer look at the Job Details.

* participatory research in which local community members are involved as co-researchers.





This is a really exciting project working with Tim Schwanen (Twitter) in an extremely supportive environment with great colleagues in an excellent research center. I would jump at this opportunity if I could.


Friday, June 29, 2018

Quote of the Day: induced demand


“We assume that car use is an incompressible liquid that must be routed somewhere. But it’s more more like a gas that fills whatever space it's given.” Ian Lockwood, HT Taras Grescoe

Thursday, June 28, 2018

8th Anniversary of Urban Demographics Blog!

Just a few days ago, the Urban Demographics blog had its 8th Anniversary. I have reduced the activity in the blog quite a bit over the past year because I moved houses twice (from Oxford to Cambridge the other place, and then from the other place to Brasilia), and also because I've tried to procrastinate less focus on my thesis writing (more news on this soon). Still, this has been a great year, specially because I've had the chance to meet in person a few dozens of people who told me the blog had been actually helpful in pointing out useful study references, data sources etc. Please, feel free to drop me a line with suggestions on how to improve the blog.

Here just a few quick stats that show a summary of the blog over the past year. 

The 5 most popular posts:
  1. How much residential space could you rent with $1,500 in 30 global cities?
  2. The long-term effect of slavery on inequality today
  3. Using deep learning and Google Street View to estimate the socioeconomic characteristics of neighborhoods
  4. Heads up for some useful R packages
  5. Making a geogif with QGIS


Where do readers come from? (164 countries | 4,217 Cities) 
  1. United States (32.9%)
  2. Brazil (8%)
  3. United Kingdom (7.4%)
  4. Canada (3.8%)
  5. Germany (3.5%)

Thursday, June 21, 2018

On my way to Dar es Salaam

The blog has been quiet lately because I've been trying to finish my PhD thesis  I've been saying this for over a year now   but here are two quick updates. 

The 4th paper of my PhD has been accepted for publication in the Journal of Transport Geography \o/. You can read the pre-print of the study here.


The second update is that I will be in Dar es Salaam next week presenting this paper at a workshop organized by the Volvo Research and Education Foundation (VREF), who also kindly invited me to attend the Mobilize summit organized by ITDP.

I'm very excited to learn about some of the urban development challenges faced by African cities. This will also be a great opportunity to discuss how we can improve research methods to assess the equity impacts of transport policies on people's access to opportunities.

Wednesday, June 13, 2018

Staying away from trouble

When your boss is looking for you to discuss that project report but you just want to finish your PhD thesis. #truestory


image credit: ? via Glaucia Marcondes

Friday, June 8, 2018

Globally consistent estimate of carbon footprints of 189 countries and 13,000 cities

Daniel D Moran et colleagues developed the Global Gridded Model of Carbon Footprints (GGMCF). This model provides a globally consistent and spatially resolved (250m) estimate of carbon footprints in per capita and absolute terms across 189 countries. Their paper got recently accepted for publication (see below) and their data is freely available. Kudos to the team!

Moran, D., Kanemoto, K., Jiborn, M., Wood, R., Többen, J., & Seto, K. (2018). Carbon footprints of 13,000 cities. Environmental Research Letters.

Abstract:
While it is understood that cities generate the majority of carbon emissions, for most cities, towns, and rural areas around the world no carbon footprint (CF) has been estimated. The Gridded Global Model of City Footprints (GGMCF) presented here downscales national CFs into a 250m gridded model using data on population, purchasing power, and existing subnational CF studies from the US, China, EU, and Japan. Studies have shown that CFs are highly concentrated by income, with the top decile of earners driving 30-45% of emissions. Even allowing for significant modeling uncertainties, we find that emissions are similarly concentrated in a small number of cities. The highest emitting 100 urban areas (defined as contiguous population clusters) account for 18% of the global carbon footprint. While many of the cities with the highest footprints are in countries with high carbon footprints, nearly one quarter of the top cities (41 of the top 200) are in countries with relatively low emissions. In these cities population and affluence combine to drive footprints at a scale similar to those of cities in high-income countries. We conclude that concerted action by a limited number of local governments can have a disproportionate impact on global emissions.

credit: Moran et al

Tuesday, June 5, 2018

PolicySpace: agent-based modeling for public policy analysis

I've posted before about the "Humans of Simulated New York", a comprehensive agent-based model (ABM) of city life that is being led by Francis Tseng.

On a similar vein, my colleague from Ipea Bernardo Furtado has been developing the PolicySpace project, an agent-based modelling platform for public policy analysis. According to Furtado:


"PolicySpace is an agent-based model, including families, citizens, residences, businesses, markets, taxes, mobility, and municipalities, that allows “what-if” questions. It is an in silico laboratory, of extremely low relative cost. Yet, it is flexible, adaptable, that anticipates trajectories and, quantitatively, measures horizontal effects across sectors, places and times. The book reviews the literature, explains concepts, and describes the methodology. It details the model, its parameters, and the full process. It validates the proposal and illustrates with applications."



The platform allows for the ex-ante evaluation/simulation of public policy alternatives in a way that takes into account the emergent complexity of the interactions between portions of society and institutions, in space and time. PolicySpace was originally designed for the Brazilian case but it is easily adaptable to other contexts. The code is written in Python, it is open source and the full code is available on Github. The platform is also modular, so it can expanded in a flexible way to gradually incorporate different aspects considered to be relevant for a variety of policy realms. For example, Francis Tseng is further expanding the PolicySpace platform to incorporate public and private urban transportation at fine spatial scale.

Earlier this year, Bernardo published a book where he presents a literature review of ABM and where he introduces, validates and demonstrates applications of PolicySpaceThe book PDF is freely available both in English and in Portuguese.

Give Bernardo a shout if you would like to collaborate on the project, use it in your own applications or just give him some feedback.  He is co-organizing a special issue on Complexity Science and Public Policy, so some of you might be interested in that as well.


image credit: Francis Tseng and Bernardo Furtado

Thursday, May 31, 2018

Should cyclists be forced to wear helmets?

Here is a short summary of the evidence on bike helmets and cycle safety provided by some experts interviewed by the Guardian - HT Rachel Aldred and Phil Maynard.

Saturday, May 26, 2018

The creative process lollipop chart

Stefanie Posavec came up with this brilliant 'chart' to illustrate the creative process of coming up with a great idea.

It reminds me of a story of this Brazilian band (Paralamas do Sucesso), when the lead singer/composer was asked about their success. Long time ago a journalist asked him: "When a band releases a new album, they usually get one maybe two songs in the top hits. How come you get so many top hits for every new album you release after so many years on the road?". His secrete, his said, was that every day he would write the lyrics of a new song. It took a lot of discipline, for sure, but at the end of the year he would have more than 300 songs. Most of them would suck, of course, but certainly a few would be good material that could be worked further.

Ok, I don't remember the exact words of the dialogue, but you get the idea. And frankly, I think that's a good advice for young researchers looking for good research questions. Read a lot of papers so you have an informed understanding of what are the knowledge gaps in your field. Then put yourself to ask as many questions as you can think of and write them down without censoring yourself. At some point you will have many questions (20? 50?). Revisit your list of questions after a few weeks and some more reading. You'll realize most of them won't work. Some are too ambitious, some have been answered already, some are just not that relevant etc. Once you have three or four questions that sound reasonably good, it's time to do more reading and to discuss these questions with more experienced mentors/supervisors/friends. Remember to be humble.

"You ask me if I keep a notebook to record my great ideas. I've only ever had one." (Albert Einstein )

The bottom line is this:

Tuesday, May 22, 2018

Using deep learning and satellite imagery to improve land use classification in cities

Marta Gonzalez and colleagues have a recent paper using deep learning and satellite image data to improve land use classification. The authors have made documented code and Jupyter notebooks available hereI'm self recommitting the paper and code to my future self. HT Marco De Nadai.


Albert, A., Kaur, J., & Gonzalez, M. C. (2017, August). Using convolutional networks and satellite imagery to identify patterns in urban environments at a large scale. In Proceedings of the 23rd ACM SIGKDD International Conference on Knowledge Discovery and Data Mining (pp. 1357-1366). ACM.


Abstact:
Urban planning applications (energy audits, investment, etc.) require an understanding of built infrastructure and its environment, i.e., both low-level, physical features (amount of vegetation, building area and geometry etc.), as well as higher-level concepts such as land use classes (which encode expert understanding of socio-economic end uses). This kind of data is expensive and labor-intensive to obtain, which limits its availability (particularly in developing countries). We analyze patterns in land use in urban neighborhoods using large-scale satellite imagery data (which is available worldwide from third-party providers) and state-of-the-art computer vision techniques based on deep convolutional neural networks. For supervision, given the limited availability of standard benchmarks for remote-sensing data, we obtain ground truth land use class labels carefully sampled from open-source surveys, in particular the Urban Atlas land classification dataset of $20$ land use classes across $~300$ European cities. We use this data to train and compare deep architectures which have recently shown good performance on standard computer vision tasks (image classification and segmentation), including on geospatial data. Furthermore, we show that the deep representations extracted from satellite imagery of urban environments can be used to compare neighborhoods across several cities. We make our dataset available for other machine learning researchers to use for remote-sensing applications.


Tuesday, May 15, 2018

Urban Picture

Nova Iguaçu (Brazil). Nova Iguaçu is a municipality in the Metropolitan Area of Rio de Janeiro. The ocean and some of Rio's mountains can be seen in the background of the picture.



source: vonsenke on reddit, HT Vitor Gabriel

Sunday, May 13, 2018

Against All Authority

Happy mothers day

credit: ?

Tuesday, May 8, 2018

Visualizing space-time networks

I've said this on Twitter before but I should say it here as well. Craig Taylor and the Ito World team have some of the best data visualizations of geospatial data related to cities and transport networks.

Just a few days ago, Craig tweeted some of his latest work with neat visualizations of drive-time network for catchment area analysis. Here is a video comparing different cities in the UK and a brief explanation on how to read the dataviz.
"30 minute drive time analysis from major UK cities visualised as 3d coral geometry. 
The thickness of artery is proportional to the number of networks connected to it indicating busier routes. The falloff in height is linked to the proximity to the centre. 
Corals aren’t normalised in scale as the purpose of this is visualising the form and pattern the networks create. Animation is a boomerang motion scaling from 0 to 30 min and back again. Congestion/traffic not accounted for."

click at the bottom of the video to watch it in full screen and high definition



Yep, there are some obvious parallels here with Time Geography and in particular with the representation of space-time prisms. The static version of the space-time trees gives a sharper visualization of the data.

The space-time tree, or 3d coral geometry as Craig said.

and the inverted original dataviz, "the drive time web"

Thursday, May 3, 2018

Cities in Brazil: A Law and Economics Research Agenda

Just a few days ago, Edward Glaeser presented at the Harvard Law School Brazilian Association Legal Symposium (video below). Glaeser talked about his recent research and some of the questions it raises towards a research agenda on various challenges faced by cities in Brazil but also in other countries from the developing world. This is a self-recommendation post, I haven't watched the full video yet. Hat tip Bruno Bodart.


ps. curious fact mentioned in the video. Glaeser's PhD thesis advisor at Chicago was the Brazilian economist José Scheinkman.


Wednesday, April 25, 2018

When the deadline is close and you need to finish that manuscript

This is how I feel my PhD thesis looks like right now.

image source: reddit