Sam Smith

Notes on a trip to China

Thu, 26 Feb 2026 00:00:00 +0000

In September 2025 my wife and I spent just over 3 week in China, her first time back to her home country in 2 years and my third trip there, having been in 2017 and 2018. We spent most of our time in my wife’s home city of Chengdu, while also visited the nearby cities of Chongqing and Guiyang. This post is a collection of my thoughts and opinions on the places we visited, along with some photos I took during the trip.

文殊院 Wenshu Temple, Chengdu

Chengdu

When I first went to Chengdu in 2018 I wasn’t very interested in the place, it’s very flat and generally lacking in visual interest, but I did meet my wife there so I do have a bit of a soft spot for the place. When I travel alone I tend to spend most of my time just exploring and looking for interesting areas to photograph, and Chengdu isn’t great for that. Going back with my wife was much different, she knows all the best spots and between her missing the food she’d grown up with and me having more of an interest than I did last time, we spent a lot of time eating.

Chengdu is, in my mind, the best food city in the world when it comes to native cuisine, not that I’m claiming to be an expert in this regard. My favourites were: 甜‍水‍面 Tian Shui Mian, thicky chewy noodles with a delicious spicy sauce¹ – 钟‍水‍饺 Zhong Shuijiao, simple pork dumplings with a different but equally delicious spicy sauce² – and of course 火‍锅 Huo Guo, or hot pot, where you get a big pot of spicy broth on a burner in the middle of your table and a selection of meats and vegetables to cook in it.³

均隆滨河路 Junlong Binhe Road, Chengdu

There’s also a recent boom of nice coffee shops and really good coffee in Chengdu. It’s not hard to find a specialist coffee shop, they almost always have a choice of beans, and that choice almost always includes a sour and fruity light roast which made me very happy – my top recommendation is agua café.⁴ I found walking around Chengdu, particularly in the area near where we stayed, around the 牛‍王‍庙 Niuwangmiao metro station, I was constantly seeing nice looking restaurants, coffee shops, and bars that I wanted to visit. I have the same experience every time we visit Paris.

Getting around Chengdu is easy. The street layout feels like it was built with the superblocks⁵ idea in mind. There’s something of a grid of large roads, and inside the blocks created by this grid are a maze of smaller much quieter streets which are much more pleasant to walk on, if you can find a reasonable route through. Crossing these large roads is a frustrating experience. First you have to get across the slip lane with limited visibility around the corner and where no cars will stop for you, then you’re waiting multiple minutes on the island with no shade and surrounded by people on scooters until you get to cross. On the other hand, Chengdu’s metro is amazing, the coverage is very good, the platforms tend to be very close to ground level so it’s quick to get to the trains, and it’s very fast and frequent.

人民公园 People’s Park, Chengdu

The Train

There’s not much to complain about with China’s high speed rail system. The headline being the high speed, we took a train from Chengdu East Station to Shapingba in Chongqing, travelling 299km in 62 minutes, which means we averaged almost 300km/h. I also liked how my wife was able to choose seats before booking our tickets, which meant if we weren’t able to get seats next to each other, we could just travel at a different time – and, we didn’t try this, but you can order food from a restaurant near a station you’re stopping at to be delivered to your seat.

I’m not a fan of the more airport like experience of the stations. They tend to be further towards the edge of the city, albeit much closer than an airport and of course well connected by metro. You have to go through some security theatre to get into the station which is annoying, especially for me carrying film that I’d like to avoid putting through the scanners (that said, they were always happy to hand check it when asked). The check does tend to be quick and I never saw much of a queue. The waiting area is usually a huge hall with a selection of shops, quite a bit of seating, and rows of escalators to get down to platform level. You can only go to the platform shortly before your departure, so there’s another queue to wait in and crowd to navigate to scan your ticket and board.

Chongqing

朝天门广场 Chaotianmen Square, Chongqing

On my previous visit to Chongqing in 2018 I was really taken by the city. It is, at least in terms of urban form and landscape, the total opposite of Chengdu. Chongqing is a huge city built on almost mountainous terrain, at the confluence of two large rivers. It often feels like everything is built on top of everything else, you can be on the ground floor on one side of a building and the 20th floor on the other side. I enjoy photographing how human infrastructure interacts with nature and Chongqing is full of interesting examples of this.

During this visit I had less time to explore the odd corners of the city, but we still got around a good bit. We repeated a walk I had done previously, going from 李‍子‍坝 Liziba station (where the monorail passes through an apartment building, which was very quiet in 2018 but now a busy tourist attraction) up a steep hillside the eventually make it to the pagoda at the top of 鹅‍岭‍公‍园 Eling Park. The route took us up steep sets of stairs past some abandoned buildings, then into a wealthier hilltop neighbourhood, and finally the park. For me, Chongqing is a city to be explored on foot, there’s constantly cool things to see and the terrain gives you interesting vantage points from which to see them. This can, however, be a bit less fun when you consider the weather. It can get very hot and very humid in Chongqing, it’s considered one of China’s oven cities. When we were there in September it mercifully stayed in the low 30s, but that heat combined with seemingly having to walk uphill to get anywhere can be pretty brutal.

嘉陵江 Jialing River, Chongqing

Finding nice coffee in Chongqing wasn’t so easy, multiple places we found online and tried to visit weren’t open when they said they were, which sometimes meant quite a bit of walking around in the excessive heat. The best spot we found was Guaguajun coffee on Daijia Alley, which also had a great view over the Jialing River.

Chongqing has a huge metro system, including two monorail lines. Line 2 is particularly scenic, following the south bank of the Jialing River for a section. It can often still take quite a bit of effort to get to a train, with deep stations and long corridors for transferring between lines, another impact of the terrain. One station we visited, 红‍土‍地 Hongtudi, took 6 escalators to get down to platform level, and that’s not even the deepest. We went to Hongtudi to experience another form of physical punishment enjoyed by Chongqingers – their brutally spicy and mouth-numbing hot pot. Specifically for a hot pot restaurant in a 500m long air raid shelter built during WWII.

长江 Yangtze River, Chongqing

Guiyang

Guiyang is the only city we visited on this trip that I hadn’t been to before. It’s significantly smaller than the other two cities, with just 4.5 million people, compared to 16 and 11 million in Chengdu and Chongqing. I also generally found it the least interesting of the three. Guiyang is built on hills, but nowhere near to the degree that Chongqing is, so it doesn’t really give the same sorts of views. The streets are much narrower than those in Chengdu and it doesn’t have the same sort of super-block structure, but the streets are still very car oriented so you end up with a pretty poor pedestrian experience. What is interesting is the proliferation of pedestrian underpasses, which exist under many four-way junctions around town, and these are often full of shops. This is nice as it lets your briefly avoid the heat and not have to wait to cross, but to me it just reinforces the feeling of being second class compared to cars.

南明河 Nanming River, Guiyang

The reason to visit Guiyang is the food, it has a very distinct cuisine compared to Chengdu and Chongqing (and the rest of China). We tried sour noodles, which came with a bucket of raw, unpeeled garlic cloves on the table for you to chew on – multiple different types of hot pot that I hadn’t heard of before, one with a bean flavoured soup base and another that was mostly just a big pot of tomatoes and chicken – and the highlight was 烙‍锅 Lao Guo, which is conceptually similar to hot pot except instead of a pot of hot broth you have a large pan on which to cook your various meats and vegetables, with a bowl of spicy dip in the centre.

Guiyang also has a lively specialty coffee scene, but at least in the short time we spent there I didn’t find any coffee I liked as much as what we were having in Chengdu. We queued outside Captain George⁶, the pioneer of specialty coffee in Guiyang, and tried to visit DuiDe Coffee each morning only to find it with a large queue each time until the third day. For me neither lived up to the hype.

南明河 Nanming River, Guiyang

Parting Thoughts

We had a great time on our trip, I particularly enjoyed Chengdu and would love to go back, I still feel like there’s a lot more exploring to do in Chongqing, and I’m very glad we went to Guiyang but I don’t think I’d go out of my way to return.

All the photos in the post were shot on my Hasselblad 501c with an 80mm f/2.8 CB lens using Ilford HP5+ shot at ISO 800 and developed in Ilfotec HC 1:49 for 11 minutes. I scanned them with an Epson V800 and edited them in darktable.

With thanks to my wife for making the trip what it was, as well as for helping me put together this post.

See We Tried China’s Iconic Sichuan Sweet Water Noodles – Bon Appétit https://www.youtube.com/watch?v=zVFcNCsiZII ↩︎
See The Legendary Chinese Dumplings Served in an Auntie’s Living Room – Bon Appétit https://www.youtube.com/watch?v=i_y-Eg2xX_M ↩︎
With a hot pot, you’ll also always have your own little customisable dip bowl, and my tip for if you’re like me and not great with spice is to fill it mostly with vinegar, this really helps to manage the spiciness. ↩︎
https://www.instagram.com/cafe.agua ↩︎
Superblocks are an urban planning concept, in which city blocks are combined together, allowing traffic to flow around, but only cars heading to a destination within the superblock are allowed to drive in. The concept is usually associated with it’s implementation in Barcelona. ↩︎
https://www.instagram.com/captaingeorgecoffee_ ↩︎

This site is moving

Wed, 14 Jan 2026 00:00:00 +0000

I have finally bought a domain for this website and it is moving to samsm.ch. It will continue to be available at sams96.github.io for the time being but that should change at some point and will do so without warning.

Photo Series: Standout

Sun, 20 Jul 2025 00:00:00 +0000

Standout is a short series of shots taken in Switzerland between March 2021 and May 2024. They are photos showing telephone poles, electricity pylons, signposts, and fence posts standing out.

Every photo in the series was shot on my Hasselblad 501c with either a 60mm f/3.5 CF or 80mm f/2.8 CB lens using Ilford HP5+ shot at ISO 800 and developed in Ilfotec HC 1:49 for 11 minutes. I scanned them with an Epson V800 and edited them in darktable.

Always Sort by ID — An Interesting Gotcha

Tue, 27 May 2025 00:00:00 +0000

If you’re writing a database query for your web service and there’s pagination, you should always sort by a unique field like ID. This should also be done on top of any other sorting. Otherwise you can get double entries or lose results across pages.

A sort can be non-determinstic, as in if you have multiple items with the same value in the field you are sorting by, there are multiple valid ways to sort it. This can be okay, until you need that sorting to persist through multiple queries, as you will when using pagination. This means that your query for your second page could sort your results differently and give the same entry again, or completely miss an entry. In the example below, both tables show valid ways to sort by Customer Name, but give different results which in this case leads to one order being missed and another shown twice.

Page 1

The first two results are returned.

	ID	Customer name	Item Ordered
->	1	Alan	Apple
->	2	Betty	Banana
	3	Betty	Grape
	4	Callum	Apple

Page 2

Now with an offset of 2 the third and forth results are returned, but because we are sorting in an non-determinstic way, the order has changed and we get different results than expected.

	ID	Customer name	Item Ordered
	1	Alan	Apple
	3	Betty	Grape
->	2	Betty	Banana
->	4	Callum	Apple

This only applies when using the classic LIMIT and OFFSET method of pagination. Other methods are available, but those tend to come with other downsides that make them less viable for the type of web services I work on, requiring either more resources or less flexibility.

The simple solution here is to just always include a sort by a unique ID, on top of any existing sorting or any requested by the client. That way your sorting is always deterministic and no results are lost.

Rgeo — 5 Years On

Sat, 08 Mar 2025 00:00:00 +0000

5 years ago I wrote Rgeo, a small Go package for reverse geocoding (you input some coordinates, it gives you information about the location). Today I am putting the projected on an indefinite hiatus.

That’s maybe a tad dramatic for my little project that I barely touch anyway, but I thought I should be clear about the fact that I’m not really working on it at all, and I thought I’d just write up my thoughts about it here.

In the time since, Rgeo has been noticed somewhat (much more than I expected), gaining over 50 stars on GitHub and getting some really nice contributions. I am very happy with how the project has been received by others, despite my neglect.

My main motivation for writing Rgeo in the first place was as a portfolio piece, something that I could show prospective employers to prove that I can write decent Go code, since at that time I didn’t have any professional experience. It served that purpose well, I got a job writing Go not long after the initial release. And after that I lost the motivation to work on it, since I had a full time job writing Go.

I have been reflecting on this project recently because, despite the fact that I am still waiting Go professionally, I’ve had some more motivation to work on my own projects, but not this project. I don’t have any use for the package myself so I’m not finding issues nor coming up with new features to add.

What to use now

smilyorg/tinygpkg - Very nice package inspired by Rgeo. It uses a different approach to vastly reduce startup time at the cost of slightly slower queries.
authenticvision/rgeo - The most active fork of Rgeo, and most of the contributions I’ve had have come from these guys.
Rgeo - There’s no external API calls here so I don’t really see there being any security concerns, and I will try to keep dependencies up to date and be better at merging any fixes that come in. There just won’t be any new features for the time being (not that there has been for a while).

Rgeo v2.0

I have an idea of what I would like to do for a version 2 if I ever come back to this project, and that is to split the querying logic (which would stay in the main package) from the parts specific to the natural earth data geojson files used (which would go into a new sub-package). This would provide a more general use for the package in handling data from any source while still giving easy access to the same existing functionality. I also like SaTae66’s snapping PR, but I wonder if similarly things could be generalised and more tools could be provided, for example querying for the closest geojson feature to a given point.

Applying Hexagonal Architecture to a Mid-Size Go Backend

Wed, 26 Feb 2025 00:00:00 +0000

I’ve been working on web backends in Go for the past 5 years, and on various projects of covering a range of ages from brand new greenfield projects to one built on top of a core that predates the Go language. The needs of these backends tend not to be overly complex, handling user management, payments, and a relativly simple product. They’re maintained by teams of 2-20 backend engineers and work with a SPA web frontend communicating with JSON over HTTP.

With my most recent work being mostly greenfield, I’ve been thinking more about how I can apply what I’ve learned from my colleagues working on older projects, and avoid decisions made in the name of moving fast which cause a lot of pain further down the line.

What needs to be considered when it comes to layout out a project is finding the right balance of flexibility without over-abstracting. You want to be able to move quickly and adapt to ever-changing requirements without being slowed down by your own code. This heavily depends on what you’re working on, but I’m going present what I find works for me for the type of projects I have experience working on.

I arrived at this layout not purely by attempting to apply hexagonal architecture to the projects I have worked on. It is something that I have read about and is often brought up when it comes to Go project layouts, but I have arrived here mostly through my experience and by thinking about how to find the right level of abstraction that works well for these projects.

Hexagonal architecture splits packages into one of two types: the application’s core and its adapters. The core being the part that defines your application’s business logic and ties the adapters together, and the adapters being wrappers around external services or other external communication. I would further add a third type to this, which is utility packages that fill neither of the above roles.

Core

Core packages should contain all of your main type definitions which the adapters will also be built around, as well as functions defining the actions that can take place. In the simplest case this could just be a wrapper around a database function, but it could also involve much more, including validation and coordination of different adapters.

You can split your core where you have clear seperation between domains. A simple example of this is splitting the user management away from the actual functionality of your application (assuming that the functionailty isn’t heavily relieant on user management). If your application is small, you can just leave it all in one package. If you aren’t sure, just leave it in one package until clear lines emerge¹.

Below I have used a simple user management package as an example framework for a core package. I have omitted contexts (which you really should be passing) and imports for brevity. All code samples in this article are for illustrative purposes only, don’t expect them to work as is.

package users

type User struct {
	ID uuid.UUID
	Email string
}

type UserStorer interface {
	NewUser(email, password string) (*User, error)
}

type Manager struct {
	store UserStorer
}

func NewManager(store UserStorer) *Manager {
	return &Manager{
		store: store,
	}
}

func (m *Manager) New(email, password string) (*User, error) {
	...
}

The UserStorer here will likely only have one definition. Even though as developers we like the idea of having flexibility to swap out the database easily, in my experience in a commercial setting it’s very unlikely to happen. I also don’t think it’s really needed for testing, I would just write integration tests here and run against the DB instead of mocking it. That said, I like to have the interface defined here anyway because it fits nicely with the philosphy of core package and having it define what the adapters do.

Ideally, your core packages won’t be dependant on each other and you can keep everything entirely separate, however this often isn’t the case. In some simple cases, you can just rely on the layer above (the driving adapter, see below) to call separate functions in different core packages. For more complex dependencies, I think it’s fine for the core packages to sometimes be dependant on one another (i.e my user manager might include a manager of another domain). The Go compiler’s blocking of circular dependencies should prevent things from getting too complex here.

Adapters

Adapters are what let your core code communicate with the outside world. They generally exist either as a wrapper around some third party service in order for it to conform to an interface that has been defined in the core, the obvious example being your database layer, or as an API calling the functions in your core package. These are sometimes referred to as driven and driving adapters.

Driven Adapters

Driven adapters are those called by your core package, and should satisy the interface defined there. The most common example, and the one I’ve used as an example below is a database but they could also easily be a key-value store or object storage. Beyond that, the same pattern can be used to send analytics events or transactional emails.

package postgres

type DB struct {
	db *sqlx.DB
}

func NewDB(/* connection info */) *DB { ... }

func (db *DB) NewUser(email, password string) (*User, error) { ... }

I would keep all of the code relating to a single external service in the same package, so even if you have multiple core packages interacting with one. If it’s a single db, all of the database code can go in one place².

Driving Adapters

A driving adapter is one that calls the functions in your core, and makes them available externally. For this example I’m going to use a simple REST³ API for our user service, designed for some SPA frontend, as this is what I have most commonly encountered.

package webapi

type Handlers struct {
	users *users.Manager
}

func NewHandlers(users *users.Manager) *Handlers {
	return &Handlers{users: users}
}

func (h *Handlers) Route(mux *http.ServeMux) {
	mux.HandleFunc("POST /register", h.handlePostRegister)
}

func (h *Handlers) handlePostRegister(w http.ResponseWriter, r *http.Request) {
	var req postRegisterRequest
	err := json.NewDecoder(r.Body).Decode(&req)
	if err != nil {
		/* handle error */
	}

	user, err := h.users.New(req.Email, req.Password)
	if err != nil {
		/* handle error */
	}

	resp := postRegisterResponse{
		UserID: user.ID,
	}
	err = json.NewEncoder(w).Encode(&resp)
	if err != nil {
		/* handle error */
	}

	w.WriteHeader(http.StatusCreated)
}

When it comes to factoring this package, I like to divide it by intended consumer, so routes for your SPA frontend go in one place, and webhook handlers go in another etc. That way the request and reply formats and expectations of all routes in one package is the same, as is the authentication.

Utilities

Utility packages are those that don’t fit into either previous category, by both not implementing business logic and not interacting direcltly with an external service. Aside from any convenience abstractions that you want to reuse in multiple packages, the main thing I expect to fit this category in our web app is authorization. Auth kind of fits in with the driving adapter, but also splits of nicely, and if you’re exposing multiple APIs you’re probably going to reuse some of the code.

Also, don’t take this category as a suggestion to create a utils package. Generically named packages like this are recommended against in go, and A little copying is better than a little dependancy⁴.

Conclusion and other thoughts

When it comes to the folder structure, I would advise keeping everything as flat as possible, Subfolders are nice where you have a bunch of non-go files related to a package, such as your database migrations. You probably don’t need a src, pkg, or internal folder to contain other packages. You can just leave everything in the top level of your repo. These make sense in very large projects like Moby or Kubernetes, but for our web service you’re just making things harder to find. Leave it at the top level until that starts to cause issues.

As I said at the top, this is the layout that I’ve arrived at from my experience working on commercial web backends in Go. I think it’s a practical level of abstraction to stay flexible without spending too much time or adding too much complexity.

You might think that there isn’t actually much to what I have suggested here, but that’s part of the point. You don’t need much abstraction and not having it will help reduce the mental load of working on your codebase, allowing you to focus on productive work and for new developers to be onboarded more easily.

Portfolio V - 2020

Sun, 19 Dec 2021 00:00:00 +0000

This year was, unlike the previous few, without any major travel. Although I did move from the UK to Switzerland, which did give me a new place to explore and photograph. Even with that I took a fraction of the number of photos I usually take in a year in 2020, which left me with not much to choose from for this selection. I chose to still put it together though because I like that this has become somewhat of a yearly reflection (even if it does take me the better part of the next year to put them together) and I thought that given it was somewhat of an interesting year it could be nice to have this record.

Along with the reduced number of photos taken came a complete lack of work towards any larger serious projects, although I have started a couple of collections of images taken with my phone that could become something eventually.

Grand Union Canal

Worcester & Birmingham Canal I

Worcester & Birmingham Canal II

Sihl

Stockwald

Melchsee

Bettenalp

Balconies I

Balconies II

Siedlung Langgrüt

Fernsehturm Üetliburg

Schlittelweg Üetliberg

This year actually came with a change in equipment. I swapped out my Hasselblad 500C/M for a newer 501C, and with the change gained an 80mm CB lens, which which all but one of the above images were taken. I did however stick with the trusty Ilford HP5+ throughout, all shot at 400 except the last two which were at 800.

August 01

Tue, 03 Aug 2021 00:00:00 +0000

August 01 is Swiss national day, and one of the few days of the year that it’s legal to set off fireworks here in Zurich. I decided to head out in the evening with my digital camera to see the fireworks and take a few photos, primarily just for myself and maybe to put a few on my Instagram story (hence the vertial compositions). In the end I thought I had a nice little atmospheric photo series which would fit nicely here.

Portfolio IV - 2019

Sun, 22 Nov 2020 00:00:00 +0000

2019 was another active year for me, with a trip to Venice in July and then a long trip to Barcelona, the U.S, Vietnam, Thailand but mostly Taiwan. I only shot colour film in Vietnam and Thailand so those won’t appear here, and my film from Thailand was actually the first film I’ve posted to a lab due to running out of chems and Corona, and they were annoyingly lost before they made it there.

I didn’t do as much towards photo series in 2019 as I would’ve liked to. I did make together my New York Architecture post and put together a series of images I shot in Nottingham since I started studying there. I did think about starting a series many times throughout the year but I left Nottingham in June and didn’t know where I was going to be in the longer term so I didn’t want to start anything big that I wouldn’t be able to finish.

Brinklow Tower

Wollaton Oak

Llangrannog Beach

Talley Woodland

Wollaton Deer

Nordic Pavilion

Chatham Green

Americana Submarine

Hilliard Towers

Hualien Breakwater

Huajiang Riverside Park

Power Lines

As usual all of these images were, again, shot with my Hasselblad 500C/M and 60mm CF and 150mm CF lenses on Ilford film. Mostly HP5+ at 400 or 800, but the last shot is at 3200, and two in the middle are Pan F+.

Edgeland Nottingham

Sun, 29 Mar 2020 00:00:00 +0000

I was recently looking through all the photos I took during my 4 years living in Nottingham to see if I could come up with some kind of series out of them. After cutting it down to all the black & white images that turned out reasonably I had just over 200 photos so I needed to come up with some more specific ideas. One theme I tend to shoot a lot is where nature meets the built environment, which lead me to put together this series. I got the title, and some inspiration, from Robin Friend’s Bastard Countryside (watch this video for a good introduction).

This series was shot with my Hasselblad 500C/M, CF 60mm and 150mm lenses, and Ilford HP5+ at EI 800 and developed in HC-110 1+49 for 11 minutes, except for image 13, which was shot on Ilford FP4+ at EI 400 and developed in HC-110 1+49 for 16 minutes.

In Feburary 2019 I started shooting a series with a similar theme in a small nature reserve in Nottingham on Fuji Pro 400H, but I’ve never been able to get acceptable scans from the 2 rolls I shot. If I do manage to get something useful from them I might put together a part 2 to this project.

Photo Series: New York Architecture

Sun, 15 Mar 2020 00:00:00 +0000

Just 15 months after I posted my Singapore Architecture photo series, I have decided to revisit this theme with some photos I took in New York last September. Despite what this series might suggest, I did explore beyond Manhattan but not as much because I found Manhattan to be the most interesting photographically.

This series was shot with my Hasselblad 500C/M and CF 150mm lens, on Ilford HP5+ shot at EI 800 and developed in HC-110 1+49 for 11 minutes.

Rgeo — A Go package for basic, fast, local reverse geocoding

Sun, 01 Mar 2020 00:00:00 +0000

Rgeo is a fast, simple solution for local reverse geocoding, Rather than relying on external software or online APIs, rgeo packages all of the data it needs in your binary. This means it will only ever work down to the level of cities , but if that’s all you need then this is the library for you.

Rgeo uses data from naturalearthdata.com, if your coordinates are going to be near specific borders I would advise checking the data beforehand (links to which are in the files). If you want to use your own dataset, check out datagen.

Key Features

Fast - So I haven’t actually benchmarked other reverse geocoding tools but on my laptop rgeo can run at under 800ns/op.
Local - Rgeo doesn’t require pinging some API, most of which either cost money to use or have severe rate limits.
Lightweight - The rgeo repo is 141MB, which is large for a Go package but compared to the 800GB needed for a full planet install of Nominatim it’s miniscule.

Installation

Download with

go get github.com/sams96/rgeo

and add

import "github.com/sams96/rgeo"

to the top of your Go file to include it in your project.

Usage

r, err := New(Provinces10, Cities10)
if err != nil {
	// Handle error
}

loc, err := r.ReverseGeocode([]float64{141.35, 43.07})
if err != nil {
	// Handle error
}

fmt.Println(loc)
// Output: <Location> Sapporo, Hokkaido, Japan (JPN), Asia

First initialise rgeo using rgeo.New,

func New(datasets ...func() []byte) (*Rgeo, error)

which takes any non-zero number of datasets as arguments. The included datasets are:

Countries110 - Just country information, smallest and lowest detail of the included datasets.
Countries10 - The same as above but with more detail.
Provinces10 - Includes province information as well as country, so can still be used alone.
Cities10 - Just city information, if you want provinces and/or countries as well use one of the above datasets with it. Once initialised you can use ReverseGeocode on the value returned by New, with your coordinates to get the location information. See the Go Docs for more information on usage.

Then use ReverseGeocode to get the location information of the given coordinate.

func (r *Rgeo) ReverseGeocode(loc geom.Coord) (Location, error)

The input is a geom.Coord, which is just a []float64 with the longitude in the zeroth position and the latitude in the first position (i.e. []float64{lon, lat}). ReverseGeocode returns a Location, which looks like this:

type Location struct {
	// Commonly used country name
	Country string `json:"country,omitempty"`

	// Formal name of country
	CountryLong string `json:"country_long,omitempty"`

	// ISO 3166-1 alpha-1 and alpha-2 codes
	CountryCode2 string `json:"country_code_2,omitempty"`
	CountryCode3 string `json:"country_code_3,omitempty"`

	Continent string `json:"continent,omitempty"`
	Region string `json:"region,omitempty"`
	SubRegion string `json:"subregion,omitempty"`

	Province string `json:"province,omitempty"`

	// ISO 3166-2 code
	ProvinceCode string `json:"province_code,omitempty"`

	City string `json:"city,omitempty"`
}

So, to put it all together:

r, err := rgeo.New(Countries110)
if err != nil {
	// Handle error
}

loc, err := r.ReverseGeocode([]float64{0, 52})
if err != nil {
	// Handle error
}

fmt.Printf("%s\n", loc.Country)
fmt.Printf("%s\n", loc.CountryLong)
fmt.Printf("%s\n", loc.CountryCode2)
fmt.Printf("%s\n", loc.CountryCode3)
fmt.Printf("%s\n", loc.Continent)
fmt.Printf("%s\n", loc.Region)
fmt.Printf("%s\n", loc.SubRegion)

// Output: United Kingdom
// United Kingdom of Great Britain and Northern Ireland
// GB
// GBR
// Europe
// Europe
// Northern Europe

Projects using rgeo

Currently the only project that I know of is my own rgeoSrv, which aims to wrap rgeo into a microservice. I am also planning on writing a command line appication to apply IPTC location tags to images that already contain geolocation information.

How it works

The data used by rgeo is made from a collection of GeoJSON files aquired from Natural Earth Data, which are packaged into Go files by datagen. The go files contain functions which return byte slices that contain the base 64 encoded, gzipped GeoJSON files. They’re packaged into function because that seems to be the only way to have the Go compiler ignore them if they aren’t used (so your program isn’t inflated by huge data files that you aren’t using).

New takes the datasets, decodes the data and parses the GeoJSON. It creates an Rgeo struct which contains an s2 shape index, a map to store the location information of each area and an s2 contains point query. The shape index contains s2 polygons for each of the areas in the given dataset, and the contains point query is what goes from the input coordinates to a shape. The map is then used to get the location information from the shape.

One thing I discovered through working on this is initialising s2 loops and polygons is very slow and there’s no way to store them that doesn’t have to run all the validation code upon loading them. I found that going from creating the s2 types every time to using geom’s IsPointInRing function yields a ~100x speed increase. I used s2 types because I wrote rgeo to be used many times in a program rather than a few, and s2’s contains point query is very fast (although I don’t have any benchmarks to hand).

Campus Lights Updates and Out-takes

Wed, 24 Jul 2019 00:00:00 +0000

It’s 5 months since I posted my project Campus Lights. Sadly I didn’t manage to make any progress with getting anything changed on campus, the person I’d emailed didn’t get back to me and my exams & dissertation took precedence so I didn’t pursue it any further.

I did manage to write a slightly extended version of the article for Emulsive, for which I also swapped out a couple of photos. I consider this to be the final version of the project and I am very happy with how it turned out.

Also reddit user ISUOnFilm created their own version of the project which I think turned out really well.

Replacement for Campus Lights 10 in Emulsive version

Replacement for Campus Lights 24 in Emulsive version

The following 3 photos are ones that I took for the project, didn’t make it into the final cut but I still wanted to share.

Campus Lights Out-take 1

Campus Lights Out-take 2

Campus Lights Out-take 3

Overall I am very pleased with how the project turned out and with how it was received. My main goal with projects going forward is to try something longer term, and I hope to revisit the topic of light pollution at some point.

Portfolio III - 2018

Tue, 18 Jun 2019 00:00:00 +0000

Having finished my last portfolio at the end of 2017 I can now start doing them yearly, so this one covers 2018. This includes two trips to the Canary islands, one to Gran Canaria in March and another to Fuerteventura in December as well as another long trip around Asia in the summer.

2018 is also the year during which I started to become more interested in collections of images rather than just single photos. I shot two rather short projects over the year, Subways and Campus Lights. I also attended a photo sequencing workshop at The Photo Parlour in Nottingham as part of the Off-Centre photo festival during which we looked at a selection of prints of my photos taken in China, which I have continued to work on.

Clifton Bridge

Barranco de los Mocanes

Two Leaves

Subways 01

Cascade Cavern

Macaque

Scrap Collectors

Victoria Harbour

Queen's Road Central

Ronghu Lake

Yuzhong

Towards Triquivijate

As usual all of these images were shot with my Hasselblad 500C/M and 60mm CF and 150mm CF lenses on Ilford film, although with a bit more variation that last year as I have included one shot taken on Delta 100 and one on Pan F+ but the rest are my usual HP5+. There’s also more photos taken with my 60mm lens included this year than there was last year.

Campus Lights

Sat, 16 Feb 2019 00:00:00 +0000

As an astronomy student and hobbyist, light pollution has sort of become my environmental issue of choice. Not only is it an annoyance to astronomers, but also damaging to wildlife as well as our health and is a large energy sink. I have taken particular notice of the amount of light pollution on my university’s campus lately as I am back living on campus after 2 years of living elsewhere, and my dissertation involves using the telescope on the roof of the physics building. This is a university that seems to boast about being green but seems to ignore this aspect of the environment.

All of the photos in this series were taken between 11pm and 2am, outside of those times of the year when things stay open through the night (around exams and big deadlines) and mostly away from the residential areas, so this should show the darkest the university gets within term time.

I have been in contact with a relevant member of staff about the situation and they seemed to be very receptive to this and I am awaiting an update. My main goal with this project is to raise some awareness for this issue while also documenting what the campus looks like before it hopefully gets darker.

This series was shot on my Hasselblad 500C/M with 150mm CF lens and Rollei CR200 film, developed by Palm Labs in Birmingham and scanned with my Epson 4180.

References

Burmese Dogs

Mon, 21 Jan 2019 00:00:00 +0000

"The pariah curs were baying the moon - it was only a quarter full and nearly down by midnight, but the dogs slept all day in the heat, and they had begun their moon-choruses already"
- George Orwell

It was on the first night of the 3 day trek from Kalaw to Inle Lake, in a small hilltop village, at about 4 a.m when, as we discovered later in the morning, we had all been awoken by the moon-choruses of a group of dogs that must have been larger than the human population of the town.

This is a series of photos I took with my phone while travelling around Burma during July 2018. I found the similarities between Burma as I visited it and how George Orwell wrote about it to be quite interesting, especially with regards to the dogs.

Photo Series: Singaporean Architecture

Sun, 02 Dec 2018 00:00:00 +0000

In another attempt at post-shooting photo series creation, I have put together a collection of architecture shots I took during my brief stay in Singapore in June of 2018.

Portfolio II

Sun, 25 Nov 2018 00:00:00 +0000

This set of images begins where the last portfolio leaves off and primarily shows my travels during the summer of 2017, with the last image being the only one outside of that. I have again chosen to stick to black and white images taken with my Hasselblad for consistency, and because it’s what I primarily use. I am planning on doing one of these with the colour photos that I’ve taken since I started shooting square format.

蒙自西路 West Mengzi Road

West Lake

Great Wall

Koishikawa Kōrakuen Garden

Tensouchi

Red Gum

Tasman Island

Lake Gordon

Adelaide Palm House

Escalators

Ulsanbawi

Clifton Boulevard

All of these images were shot on Ilford HP5+, and all but the last one pushed to ISO 800, which has become something of a default for me. Also, all but one of these images were shot with the 150mm lens, which I bought in March of 2017 and also used for the last four images in Portfolio I. I seem to use both of the lenses I own for my Hasselblad (the 60mm and 150mm) pretty evenly but I find most of the images that I take that I really like have been with the 150mm.

Qingdao Diptych

Wed, 21 Nov 2018 00:00:00 +0000

This is a pair of photos that I took from the top floor of a pagoda in 小鱼山公园 (Xiaoyushan park, or Little Fish Hill Park) in Qingdao, China.

Portfolio I

Fri, 09 Nov 2018 00:00:00 +0000

This series of photographs represents approximately a years worth of work, starting in April 2016 when I got my Hasselblad. I chose to start then not because I feel that the change of camera increased the quality of images that I was producing but rather I wanted to keep the format consistent throughout. Also it was about a year after I started shooting film, and when I started pursuing photography as a hobby.

Under the Bridge

Ruined House

Llyn Cau

Mauerpark Karaoke

Wetzsteinhorn

Matterhorn

Rocks

Wye

Fire Exit

Bickenhill Plantation

Nyhavn

Tarn Hows Road

Between taking these photos at least a year and a half ago, compiling this series 6 months ago and now, my opinion of these images doesn’t seem to have changed too much. I think I can put this down to the memories I have attached to these photos and the fact that I didn’t take a whole lot else that was any good.

Subways

Fri, 07 Sep 2018 00:00:00 +0000

This is the remnants of a failed attempt at a photo project looking at Birmingham’s pedestrian subways. I never really thought it was a very good idea for a project but I decided to give it a go anyway because I wanted to try shooting a project and it was the best idea that I had, also the subways are the sort of thing that I usually like to shoot anyway.

Everything in this series was shot with my Hasselblad 500C/M and Zeiss 60mm Distagon CF with Ilford HP5+ rated at 800 and developed with Kodak HC-110 at a dilution of 1+49 for 11 minutes. This is what I shoot most of the time anyway but I thought that the pushed HP5+ would work well for the sort of gritty feel of the subways. I shot 3 separate rolls of film on 3 different days in May of 2018. I have chosen 12 of the 23 pictures that I took that I feel fit the scope of the project.

The intention behind the project was to capture the feeling of the subways, which I think I was at least partially successful in doing. I think photos 2, 8 and 9 capture some of the dread and uncertainty I, at least used to, feel when entering one of these. At some point when hunting these things down I began to realise how quickly they were disappearing, a couple that I photographed were fenced off and one that I visited had been totally filled in. I was then also trying to document some of these before they were also demolished. The main thing that I failed to capture was a human aspect of the subways, although I’m not sure that photographing people walking through these areas or homeless people sleeping in them would be more compelling than what I have.

I gave up on the project mostly just because I’d lost interest in it. I visited almost all of the subways that I managed to find, some a few times, and despite only shooting 23 images I was starting to feel like there wasn’t really any new compositions left since they’re all quite visually similar.