Category Archives: OpenStreetMap

Coastlines fascinate

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Seems like I am pulled to the coastlines. Seems like I am not alone. People tend to gravitate towards food resources, and where the ocean meets land, and even rivers, food has always been plenty. Trade too. And the boats of course.

I have a house, in the northern parts of Norway where the shoreline is but 200 meters away. From where I live in Trondheim I can see the fjord. The ocean has  always been around.

I am one of those with fond memories of small waves, a grandfather safely steering the boat, and days blessed with sun and fishing. When the weather was less than fair we stayed in or near my grandparents house enjoying our small adventures around the old farm.

Seems also that the places I travel to these days are close to the ocean. Zanzibar is one of these fantastic places where oportunities and challenges arise practically on the shoreline. Mapping those oportunities and challenges is part of what I do. It invoves drones, big databases, partners in many institutions, researchers and more. Sometimes it comes together in a map describing the sensitivities of a coastal area. I like the thought of it, but fear that we more often than not do not have enough knowledge to present detailed enough maps.

In September we took some time off from our QGIS workshop to play around with the EPA drone. Great fun in the tennis court.

Ghana is an other of those places. My stays are usually in Accra, and although the coastline is

never far away it is merely the frame of the ocean and not much more. Inaccessible because of restricted daytime for me, the workshop participant and meetings participant. Workshops outside Accra usually end up being in Sogakope, a 60 minute drive down to Keta. But my meetings usually revolve on issues related to the ocean and its shoreline.

What’s with the coastal areas then? Here are some of the processes I am involved in:

  • Environmental atlases
  • Coastal sensitivity analysis for emergency response
  • Digitalization of drone data in coastal areas (coastline/mangrove/substrate)
  • Methods development of sensitivity assessments (both coastal and terrestrial)

I have attached a video from a recent (September 2017) trip to the Keta Lagoon area in Ghana. On a small strip of land between the Keta Lagoon and the coastline thousands of people live their lifes. The inland areas which are not flooded (remember this is a lagoon) are occasionaly flooded rendering the areas uninhabitable for parts of they year.

In the video you can see the sand traps designed to “harvest”sand so that the thin strip does not erode. You can see this as big dumps of stone perpendicular to the shoreline.

Apart from letting us see some of the areas near the coast the video also shows some highlights form a QGIS training near Sogakope.

Coastline mapping with a purpose?

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Mangrove coastline near Ikwiriri south of Dar es Salaam (from OpenStreetMap)

I’m discussing coastlines with a friend. We agree, and we do not agree. In part because I do not really know myself what a proper coastline is. Purpose is the word. -What is the purpose of the coastline, I recall us discussing. When you choose to include purpose into a discussion things could start to get fuzzy.

Is the coastline mapped with a purpose something different than the factual coastline? Hm… Well the purpose this time is to have information which later can be used for a sensitivity analysis.

Openstreetmap definition of the coastline is as follows: “The natural=coastline tag is used to mark the Mean high water spring which is the point of the highest tide. See natural=coastline for all the details. See also de:Coastline for much more details.” So there is a clear definition, but if the purpose trumps the standard suggestion…?

Despite the clear definition Openstreetmap mapping remains a highly subjective thing. It keeps humans in the loop – for better or worse. I am one of those people. I having traced thousands of features with thousand and thousand more vertexes I know that tracing features involves many decisions. The problem is that the purpuse is not as neutral and objective as I would like it to be. Humans will for better or worse continue to confuse the picture.

Some years ago I spent what must have been 20 hours tracing Tanzania coastline and mangrove areas. I thought I did well. Now I am not so sure.

What is the right choice when mapping mangroves? Is there an outer or an inner coastline?

If you map the coastline with the purpose of establishing a basis for describing the sensitive parts of a coastline, placing the coastline inside the mangroves could be a problem. Placing it outside might be a better choice for this purpose. Some times, regardless of your purpose, there is not just one right way of doing it.

I believe we need guidelines for this work which are strict. We can allways process ourselves around the issue. For the purpose of a sensitivity atlas we can “snap” the coastline to the outermost mangrove if necessary. Right?

The problem with our opensource community is that we are missing the FME part of it. Safe software is facilitating for fast conversions between formats – and they also add processing into the equation. I am starting to think that not having a sweet user interface as we can find in FME makes us lazy. When given having to make decisions for our mapping we bring purpose to the table because the transformations are too manual.

Wilderness 4: Wilderness degradation analysis

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Area with wilderness and encroachment. Visualization of change of wilderness status.

Area with wilderness and encroachment. Visualization of change of wilderness status.

Wilderness degradation happens when new encroachments are made changing the wilderness status of an area. It is a complex issue which does not easily lend it self to a GIS based analysis. I will refer to my posting on wilderness for a peek into the complex world of wilderness philosophy.

It is possible to set up a system like FME to do an analysis of changes in wilderness due to new encroachments. The procedure I made generates a wilderness degradation data set based on wilderness and (new) encroachment data. It is based on procedures used by the Norwegian government in their analysis of wilderness and encroachment. The system should however be easy to accommodate for different preconditions by manipulating the number of wilderness zones and/or their buffer distances.

To visualize the degradation of wilderness it is necessary to make a categorization and furthermore establish a cartography to carry the information to the reader. In my view this can not be done unless the author/mapmaker to some extent takes side in what is good or not good related to wilderness degradation. This will be the focus on a forthcoming posting, but I will touch into the issues here as well.

FME is but one of the potential solutions for producing the results. QGIS, GeoKettle and even PostGIS could be good alternatives. The GitHub project has room for alternative implementations.

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Wilderness 3: About the examples

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A philosophical approach towards wilderness analysis has been written. A FME-script has been designed and appropriately discussed. Now time has come to run the script on national level data to prove the concept and also open up for a discussion on challenges with the method and its results.

I have done this for several countries and will deliver the results and discuss them appropriately.

All examples are delivered as-is. There is no governmental context to the analysis. The data used for the analysis is OpenStreetMap data.

At the time of writing this article the number of examples has yet to be decided. The following are available as of writing this posting:

General challenges with the presented data are:

  • OSM data coverage
  • Encroachment criteria selection
  • Lack of context

In later postings I will look at the following:

  • Change analysis of wilderness
  • Cartography and wilderness mapping
  • Conclusions and discussion

Lokalkart for Mindland (heimstadkartlegging)

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Skjærseth sett fra oven

Skjærseth sett fra oven

Det ble ikke heimstaddiktning denne sommeren. Ikke er jeg spesielt interessert i å skrive lokalhistorie heller. Men stedsnavn og kart har interessert meg en god del. Så da ble det heimstadkartlegging og ikke heimstaddiktning.

Øya Mindland er i likhet med de fleste andre steder i Norge godt kartlagt av Kartverket i samarbeid med kommuner, fylker og andre offentlige etater. Det er stort sett ikke mulig å konkurrere med kvaliteten på kartene fra Kartverket. Men dekningen av lokale stedsnavn er ikke alltid like god. Continue reading →

Stedsnavn på øya Mindland, helgelandskysten

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Denne artikkelen handler om stedsnavn på øya Mindland i Alstahaug kommune på helgelandskysten. Mange av dem er stedsnavn jeg har vokst opp med, og som familie og venner på øya bruker den dag i dag.

Å kjenne stedsnavn er en berikelse fordi navnene ofte forteller noe om stedet, om folkene som har levd og arbeidet der og forholdet mellom sted, natur og folk. Ehaugen, Grautpailen, Timro og Gåsskrevet er navn som kan mane til ettertanke eller få latteren frem. Det kan også være praktisk å kunne referere til stedsnavn når jegerne kommuniserer over radio under elgjakta.

Mindland er velsignet med både fjelltopper, skogsområder, små vann, omkringliggende øyer og mye mer. Mange av disse stedene har, eller har hatt navn.

Flere enn meg har sett at noen av navnene er i ferd med å gå i glemmeboka. Vi har forsøkt å gjøre noe for å hindre at navnene forsvinner.

Denne teksten handler derfor litt om navnet Mindland og litt om hvordan en del av de mindre formelle navnene rundt om på øya har fått sin plassering ved bruk av OpenStreetMap. De som ønsker å benytte kartverkets løsninger kan lever endringer til rettikartet.

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The rise of an amateur architect

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Our family owns a house in the northern parts of Norway. The family spends around eight weeks there a year fishing, mowing the lawn, hiking, meeting family, eating good food and more. I have also spent a considerable part of my spare time sitting in Trondheim mapping the island using OpenStreetMap.

In all honest, the main house is due for some upgrades and repairs. We have started by upgrading two of the upstairs bedrooms. But more complex tasks are in line. The current bath was built by my grandfather some 30 years ago. The kitchen could need some paint. A wall should be torn down. And on and on it goes…

How do we plan these changes? How do we play around with our options? Pen and paper? Software? I have been looking for a tool which would let me plan the whole “estate” – from garden to loft. Line of sight analysis, landscape modelling, logging changes, versioning etc…

Ideally it should be an open source product. Easy to use. Sophisticated. Should handle modelling. Integrate with Google Earth or OpenStreetMap. I would like to have a tool integrating the best from OpenStreetMap with some fantastic architecture software. I want it all, I want it now – and preferably for free as well.

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OpenStreetMap makes Mindland mapping possible

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One of the biggest beneficiaries of OpenStreetMap is Microsoft letting OSM use their BING sattellite imagery as a backdrop for tracing objects for inclusion into OSM. One of my side projects is to make a decent map of the island where my father was born. The name of the island is Mindland. It is around 300 kms north of Trondheim, as the crow flies.

I started the project using driving an old motorcycle around the island with my iPhone in my backpack. This way I was able to make GPX-tracks for the major roads. However interesting it was to drive the trike around the island it would not be possible to go all the way. The buildings would end up being points, the fields would go uncharted and driving a motorcycle around all the minor roads might be a bit intrusive. Continue reading →