How to map coral atolls?

Ajoe-EilandenMaps in the Crowd brings us to remote and exotic places. An interesting map of a small group of islands is the ‘voorlopige uitgave’ (provisional edition) of the map of the Ajoe-Eilanden (Ayu Islands) from 1958, as part of the 1:100.000 topographical map series of Dutch New Guinea. These islands are located just north of Waigeo, northwest of New Guinea. This small archipelago is formed by two coral atolls with five islands, of which two are uninhabited. The Ayu Islands are known for its good snorkeling and scuba diving sites and its beaches as breeding grounds for the leatherback turtle. When we compare the georeferenced map with Google Satellite we can see how accurate and detailed the intertidal reefs are surveyed.

Ajoe-Eilanden legenda It is interesting to have a look at the legend below the map. Alongside common symbols for borders, settlements, roads, waterways and vegetation there is a special signature to indicate coral reefs. These reefs are the most prominent features on this sheet. You don’t see them in Google Maps but in Google Satellite they are prominently visible.

Click here to compare the georeferenced map with Google Satellite:Ajoe-Eilanden

Mapping an volcano eruption

One of the largest recorded volcano eruptions ever is the eruption of the Krakatoa in 1883. Two-third of the original Krakatoa island, situated in the Sunda Strait between Sumatra and Java, vanished after the eruption. Tsunamis caused by the eruption killed over 36,000 people in the wider area. By order of the Governor General of the Dutch East Indies, the National Geographical Institute in Brussels (surprisingly not the Topographical Bureau in either Batavia or The Hague) published a series of 43 maps, plans and graphs on 12 sheets in relation to this natural disaster. This map shows the terrain where ashes were distributed, as far as the Cocos Islands, 1200 kilometers away. The red numbers indicate the thickness of the ash layer. In the direct environment of the volcano the ash layer was more than one meter. Other maps in this series show, among other aspects, the parts of the original island that were vanished, the distribution of the tsunami waves and the flooded coasts in the Sunda Strait area.


View the georeferenced map here: Kaart van het westelijk gedeelte van den Indischen Archipel

Map of the royal tombs at Kotagede

One of the most striking maps that is georeferenced recently, is this manuscript plan of the royal tombs at Kotagede. In this historic neighbourhood in Yogyakarta the remains of the first capital of the Mataram sultanate, including its royal cemetery, are still visible. The large plan, measuring 81 x 93 cm., is in Javanese script and drawn around 1890. In the legend 295 graves are listed and in the map itself four types of graves are distinguished by colour: purple, green, red and yellow.


The image can be viewed in detail in the KITLV digital image library:

Urban planning from the nineteenth century

From time to time we will post some background story in this blog about an object in our collection.

It’s always nice to see a direct result from your work in the form of a reward or a goal you reached. With our Maps in the Crowd project we can see the result bar progressing to our end goal with each map you, the reader, georeferenced. At the moment we are close to having half of our maps done, thanks to you. Not all things in life show a direct consequence, but studying the past can give us a view how some plans can show their influence ten, twenty and maybe even a hundred years later.

Soerabaja 1898

Our story begins with a map of Surabaya from 1898. The map, made as an attachment for a research about the water supply of the city, is marked with a few red stripes. It was made for a Dutch engineer and architect named Hidde Petrus Nicolaas Halbertsma. While Halbertsma’s report is not easily available, the map clearly shows his plan. To get more clean water to the growing city, water sources from the nearby mountains needed to be used.

Soerabaja 2 1898

In a report from 1917 about the status of the water supply, Halbertsma’s work is mentioned again. The plans he worked on, almost twenty years before, serve as a base for the current urban planners. The report from 1917 states that the city is in dire need of more clean water and carefully explains the cost and processes needed to accomplish this. Haste was needed according to the writers, before 1920 the supply needed to rise with nearly 50% and even more water was needed before 1930.  Aside from a lot of interesting stories about urban planning and water supplies, the main question that rises is: Did they eventually build those reservoirs that our Dutch architect planned? The KITLV collection gives us the option to view the city over the years. Soerabaja 1925

The map above from 1925 does not show any waterworks yet at the spots planned by Halbertsma. Maybe the building did not go as planned, or there wasn’t enough funding, we don’t know. The map from 1943 however…

Soerabaja 1943

This map clearly shows the water supplies of the city. The reservoir or tower with the number 17 beneath it is almost on the same spot where our Dutch architect planned it. The reservoir is build closer to the city then Halbertsma planned, but it is there. Even today the Surabaya water works, build somewhere between 1925 and 1943, are still there: View the water works on Google Maps

If you are interested you can view the maps yourself in the links below. For more colonial city planning or architecture you can go to

Halbertsma’s map from 1898

Map of Surabaya from 1925

Map of Surabaya from 1943

Sketch map of Sumatra

From time to time we will post some background story in this blog about an object in our collection.

After the time of the Napoleonic Wars, the kingdom of the Netherlands was slowly given back her colonies in the east, most of which had been under a short British rule. The kingdom traded a few of her other colonies to the British for this deal. One of the more important treaties around this transaction is called the Anglo-Dutch Treaty of 1824.A remnant of this time is in our collection: a sketch map of the West coast of Sumatra, made around the end of the Java War (1825-1830), a few years after the treaty was signed. Spread around the map you can see notes (in Dutch) about tribes, local leaders and parts that used to belong to the English.

Hele kaart

On this map you can see blue colored areas on the coastline. In the text on the map it says that the author considered these parts under authority of the Dutch around 1830.

Engelse overname
This note says that these lands were part of the treaty of 1824. Literally it says: “This part was gained from the English since 1825.”

The map is really an all-rounder in it’s focus. The author added notes about different local leaders, tribes, and resources. Some tribes were considered rather dangerous and were described as ‘rough’ or ‘wild’.

Wilde stammen
A small, but rough tribe.

Different resources can be found on the coast of Sumatra: coal, gold and even elephants.

The deal with the British did not mean that they immediately ruled the islands of modern Indonesia. In short, a lot of unrest brewed under the people of the Dutch Indies which led to revolts all across the land. These unrest’s caused the Java War. After this war, the Dutch government tried to focus its actions mainly on Java and Sumatra, leaving the insurrections on the other islands be. The government only dealt with the local leaders on these parts of the land. On the West coast of Sumatra was the sultanate of Aceh. This is one of the area’s the Dutch found very difficult to deal with. Around these parts there was a lot of privateering and the people of Aceh were not very fond to join the Dutch colonization. Our next post in this blog will be about the unrest that followed a few decades after the treaty, the Aceh war.

Voorbode Atjeh
The Dutch note says that the coast of Aceh is a dangerous one.

You can view the map yourself in the KITLV database:


Slicing the pie

From time to time we will post some background story in this blog about an object in our collection.

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Today we want to put another map from our collection in the spotlights. This school map from the 1920’s shows the different churches spreading the christian evangelism throughout the Dutch East Indies. Many churches spent time and resources on teaching and preaching in the colonies. Nowadays churches would probably think twice before marking a territory their own, but in the early twentieth century young missionaries in training were probably very content with this map. It clearly shows which group preached in each area and also lets you see the still unmarked territories, maybe offering prospect for the missionaries in the making.

Aside from the interesting map, the author is also worth mentioning. Not a cartologist, but a theologian was responsible for this overview. Born on the island of Sulawesi in 1875, A.M. Brouwer probably seen some parts of this map during his life. At a young age he moved to the Netherlands and later on became a minister and a professor in Theology at the University of Utrecht. Besides teaching young missionaries at the university, he also worked on a new Bible translation which was finished after his death in 1948. With this new translation came a few maps from Brouwer, about the travels of Paul the Apostle and the old kingdoms of Israel and Judea.

If you want a closer look at the map you can also go to the KITLV viewer.

A geography of maps

From time to time we will post some background story in this blog about an object in our collection.


An interesting visualization tool of the results of our georeferencing project is the so-called ‘Map Finder’: a Google world map on which all georeferenced maps are indicated with a red dot. This tool shows the spatial distribution of these maps. You can see it on the ‘Results’-tab of this blog.
We have to make some reservations with the interpretation of the pattern. Only a part of the maps is already georeferenced, only a part of the KITLV collection is digitally available, and only a part (although an important one) of all produced maps of the Dutch East Indies are kept in the KITLV collection. Nevertheless, the maps that are georeferenced up to now, can be considered as a random sample of late 19th and early 20th century maps of Indonesia. Therefore , the distribution pattern provides insight into the geographical variation in mapping intensity throughout the former Dutch colony.

The most striking is the mapping density on the island of Java. Clearly, this island was the center of the Dutch East Indies, with the capital of Batavia/Jakarta and other major cities as Bandung, Semarang and Surabaya. Moreover, Java is the most populated island of Indonesia. The island of Sumatra is in second place. Here, there seem to be some clusters around some of the major cities: Banda Aceh, Medan and Padang and surprisingly Bangka Island. The other islands are mapped less intensively, with only a clear cluster of maps in Southwest-Sulawesi around Makassar.

In general, it can be concluded that there is a correlation between the mapping density and the population density of Indonesia. Even more, the dot pattern matches with the coverage of the Dutch topographical map series of Indonesia. The most dense areas are more the same as those that are covered by the large-scale topographical map series.

Tutorial on difficult and advanced maps

For anyone experiencing problems with the difficult maps in our collection, please visit the tutorial page for our new tutorial on advanced maps. We made a list of several overview maps in map series which are difficult to georeference. We hope this helps you with finding more reference points in these 19th century maps. Please leave a comment with any request on how we can help you with the georeferencing process.

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Status report: 8% has been georeferenced

We’re shifting gears with Maps in the Crowd. Over 500 maps are now georeferenced, meaning that 8% has been done. With an ever shifting top ten, it’s exciting to see that many contributors are working hard to reference our collection of old maps. In the coming days we will inform you about a part of our collection that you are currently working on. You can expect a few blogposts about some interesting maps and a short movie to invite even more people to join our project.

Again, keep up the good work!

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