Exploring Zanzibar with Mapillary: Pt 1 - The Chief Officers’ Logbook
After finishing an action-packed week at FOSS4G 2018 in Dar Es Salaam, Ed and I took the MV Kilimanjaro ferry vessel across the water to our next destination, the legendary spice island called Zanzibar. Properly speaking, Zanzibar is an archipelago consisting of two main islands—Unguja and Pemba. Unguja was our destination, along with the famous labyrinth and its port Stone Town. Planning our trip felt like a scene out of The Life Aquatic, minus red caps and speedos. Indeed, it would be our most ambitious adventure to date.
The heart of Stone Town, Zanzibar
Our baggage included four GoPro Hero5 cameras, an LG 360 camera, along with many batteries, charging cables, and power adapters. Looking at the map, there are a few primary roads that originate in Stone Town, the heart of the metropolitan area of Zanzibar City. Beyond this, there are many village roads, often without much context as to their driveability. This was something we would soon discover. While the status of OpenStreetMap in Zanzibar is currently questionable, it still remains the best authority. Tourists are encouraged to use such applications as OsmAnd or Maps.me, which rely on OSM as a basemap. Meanwhile Zanzibar City is one of 11 cities involved in the Open Cities Africa program coordinated by the World Bank. Consequently there is a flurry of mapping activity underway with the goal to make it one of the best mapped places in Africa.
The road network from Zanzibar’s main island according to OpenStreetMap
After a Friday evening spent exploring Stone Town’s winding alleyways, we set out in a rented Toyota Saturday morning to commence our mapping expedition. We mounted one GoPro on the front of the vehicle, and one on the back, and used a two meter power cable to provide charge for the cameras. Each camera has about 60 to 90 minutes of battery, so we planned to make regular stops to switch the cable between cameras and facilitate continuous image capture. The cameras also were set to capture images at 0.5 second intervals, which helps ensure very dense coverage of the roads for the best data extraction once uploaded to Mapillary. With the cameras at the ready, we buckled up and rolled out of Stone Town.
Progress was slow at first due to the intermittent downpours we encountered. Every few kilometers we’d have to get out and wipe the lens of each camera to ensure rain droplets were not obstructing the field of view. Rain can come down fast in this part of the world, inundating dirt roads in particular. As fast as it comes down though, it doesn’t take long for it to abate and clear the way for that warm Zanzibar sun.
Our camera set-up for capturing imagery
Our destination was the far northern tip of the main island, a town called Nungwi. En route however, we had an special stop to make at Mangwapani Beach. Rumors at FOSS4G told of the MV Serengeti, another ferry, which had floated away in the night while in port and run aground on the sandy shores next to a hotel. We navigated off the main road, experiencing some trial and error finding a way through the unpaved tracks in the forest. With skilled navigation and a little luck, we arrived at the parking area of a charming hotel overlooking the ocean. Packing our cameras, we headed down to the beach on foot, and quickly encountered the sight of the boat we were seeking—it would be impossible to miss it.
After standing awestruck for a few moments, we attempted to board the boat via a thick rope hanging from its port side. Other than the amusement this endeavour provided the locals, our efforts were in vain. We wandered around to the starboard side and after a with a bit more grace, clambered our way up the side of the MV Serengeti. Success! Wandering around the ship conjured images of the B-grade horror movie Ghost Ship. Seat cushions torn from their seats, life jackets strewn across the floor, and the Doctor’s Office retained nothing but a few boxes of Ibuprofen. Perhaps it is no surprise that the highlight was to be found on the bridge. Amidst the carnage lay the Chief Officers’ log book with daily entries on the weather and location of the ship.
The MV Serengeti, a ferry that ran ashore at Mangwapani Beach
We made our way off the boat, snapped some images, completing a full circuit around the vessel to give an idea of the scene on the ground. Meanwhile, I was already sending a message to the OSM Telegram group to ask if this was worth adding as a feature on the map. Later we learned from a hotel employee that the boat had made its gracious arrival five months prior, and that it was due to be dismantled and removed soon. I wondered what “soon” meant, but have yet to add it to OSM.
Back on the road, we continued north with an attempted shortcut through some rural villages. Capturing images here was quite a valuable experience, as we were able to experience first-hand what challenges humanitarian organizations face when attempting to rely on OpenStreetMap or other maps which aren’t always accurate. What appeared to be a perfectly feasible detour ended up involving a few dead ends, some friendly locals directing us to take alternate routes, and altogether difficult terrain that can only get worse when rainy season erodes much of the surface. At the same time, these areas were certainly lively and doing well, despite disconnection from paved roads. Ideally the imagery we captured can contribute to assessments of how to provide electrical access, flood protection, and emergency supplies to similar locations.
Upon our arrival at Nungwi, we could see that water had accumulated in large puddles after morning rain showers. This again served as a reminder of how delicate the road system can be when not paved, and we hope that future image collection can provide comparison over time of these roads to notice changes due to heavy use and weather.
The northern-most point of the island is occupied by the grounds of DoubleTree Hotel, an example of how the most scenic real estate in the area tends to be dominated by commercial tourism. The route to this hotel, however, didn’t appear to receive any special treatment compared to other areas, as the unpaved tracks to reach the parking area are still a significant distance from the primary paved roads. However, it does appear that hotels are somewhat easy to reach compared to many of the village areas, with the roads on OpenStreetMap generally being classified correctly in this case. A hotel like this is also emblematic of the way resources, know-how and will can enable an impressive piece of infrastructure in the unlikeliest of places.
Inspecting the DoubleTree Resort on OSM iD editor
After a brief respite and view of the ocean, we were back in the car and taking an alternate route back to Stone Town to expand the imagery coverage. With sunset at around 6:30pm, we were losing light quickly and had to make the best use of it. Anyone using Mapillary should be sure to note that it’s difficult to get quality imagery when the sun is low in the sky, as the direct light can make it difficult to see the rest of the scene.
- Maru Maru Hotel (View on Mapillary) - this three-story building sits just southwest of the Old Fort, and has a rooftop bar and restaurant with a remarkable panoramic view of Stone Town. The internet speed seemed to hover somewhere between 2 and 4mbps, for upload and download, which was enough to slowly get our imagery online. Music starts at 7pm, so it may not be too peaceful for evening work. That didn’t stop us.
- Zanzibar Coffee House (View on Mapillary) - best for a morning visit, this cafe offers 20 minute wifi vouchers as well as 8 hour internet passes for about $6 USD, and has a similar speed to Maru Maru (maybe a bit slower depending on how crowded the cafe is). Also, the avocado toast is pretty memorable, and they make a good flat white. Large tables make it a comfortable place to spend some extended time.
- Puzzle (View on Mapillary) - a cafe located near the historic Shengani Post Office, the wifi is free and probably slightly slower than the above two options. The espresso tonic with lime almost makes up for the slower speed, but this is still one of the best wifi connections in Stone Town. Additionally, a big conference table and a whiteboard are conducive to working and planning.
- Zantel - the local mobile phone company, it also works on the Tanzanian mainland but seemed to have better coverage, stronger signal, and faster speed than other providers such as Vodacom when on Zanzibar. The connection can be used for tethering with a computer, and really came in handy for image upload and other work.
The next few days would see us using all these locations as base camps, and ideally others doing similar work with mapping data can make use of these notes. We finished this first segment of the journey with an inspection of the map, planning our next steps and leaving some space for unexpected detours.
Continue on to part 2, as we recount our mission to finish mapping the primary roads of the island and meet members of the local mapping community.
/Christopher Beddow, Solutions Engineer