Author Archives: ragnvald

Data Availability and Reliability report for Ghana coastal areas

Some years ago the Norwegian Directorate for Nature Management contributed to the Oil for development program under The Norwegian Agency for Development (NORAD). The program contributes to projects in Africa, Asia and South America. Ghana was, and still is, one of the partners to the Oil for Development Program.

As part of this mission it was agreed with the Ghanaian partners that Ragnvald Larsen and Howard Frederick (as an external consultant) should visit EPA and other relevant institutions to establish a firmer basis for further collaboration on environmental data management.

The attached report is from work done in Ghana in 2012. The work was mainly done by Howard Frederick, but contributions were also done by Roger Lewis Leh (EPA) and Ragnvald Larsen.

2013-March Ghana spatial data report
2013-March Ghana spatial data report
1.3 MiB
2013-March Ghana spatial data report
2013-March Ghana spatial data report
0.8 MiB

The spatial password

A secret spot – a potential password? Hardly anyone knows about this 5 meter high rock face in the forests outside Trondheim.

Remembering passwords takes focus and time. I want to authenticate myself without having to write in a meanlingless stream of characters. I am on a weekly basis nagged by different systems to change my paswords.

We already have several biometrically based authentications metods. Fingerprints, iris scans, selfies, hand geometry and what have you. More are probably more to come. The jury is out on several of the metods. I will leave this to the experts.

Being a geographer my favourite authentication metod will rely on spatially referenced secrets buried deep inside my mind. I want to propose a novel metod for authentication. I want to use a map to navigate to a place which has a special meaning for me. It would basically work like this:

  1. I am stating my username (written)
  2. The system then asks me to authenticate my user status by asking me for one or several geographical position.

The position could be the answer to questions like these:

  • Where did you find your wallet when you lost it in 2012?
  • Where was your father born?
  • What is your favourite place to pick blueberries?
  • Where is the secret rockface outside Trondheim?
  • Where did you spend the night the 17th of november 1995?
  • and so on…

My answer would be made not by entering a string of characters. I would answer the question by panning and zooming a map to the  particular place. My answer would be to place a pin somewhere.

The method could be strengthening by asking for a combination of several places, or by varying the required precision in my answer. The answer (coordinates backoffice) would then be used to establish a string which again is the authentication variable (password).

Here are some combinations of the screen based password:

  • One position
  • Several positions
  • User traces a path

Real position combinations

  • Actual position represents the password
  • transport between several position srepresents the password
  • A track based on movements represents the password

The method will of course have it’s weaknesses. But it could work. And if someone already made this – then please send me a link!

An other variation of this method could be physical location or relocation in a given pattern. This would of course require a positional system which can not be spoofed, but where the position and its reporting is possible to confirm.

Coastlines fascinate

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.

Mindværet – nordligst del

Jeg har laget noen ortofoto av de nordligste delene av Mindværet. Mindværet er en skjærgård som ligger rett sør for øya Mindland på helgelandskysten. Øyområdet er godt egna for dagsturer med båt/kajakk. Det fins mange naturlige ankringssteder.

Området  har et rikt fugleliv. Det er dessverre amerikansk mink i området, noe som går sterkt ut over fuglelivet i området.

Ortofotoene er satt sammen av 1.355 enkeltbilder tatt fra en høyde på 120 meter over havet. Bildene er bearbeidet ved hjelp av spesialprogramvare.

Et spesielt vakkert parti med svært gode muligheter for både fortøyning og bading.

Sammenstillingen er laget med utgangspunkt i bilder som er i berøring med landområder. Oppløsningen på kartene er i full størrelse så god at de kan egne seg til utskrift i størrelsesorden 1×1 meter.

Kartene kan lastes ned og kan benyttes vederlagsfritt.

Ortofotoet viser de største øyene i området. Sjøområdene mellom mer ikke tatt med. Filen er om lag 150 Megabyte stor og kan lastes ned. Et trykk på bildet vil ta deg til en nedlastingsside.


Ortofotoet/kartet viser de største øyene i området. OpenStreetMap er benyttet som bakgrunnskart. Dermed vises også øyer i omrdet uten ortofoto. Filen er om lag 125 megabyte stor og kan lastes ned. Et trykk på bildet vil ta deg til en nedlastingsside.


Brørholmen – ortofoto

Brørholmen ligger et par hundre meter fra Mindtangen på Mindland. Kartet/ortofotoet er satt sammen av 95 separate vertikalbilder tatt med drone. Bildene er tatt fra en høyde på 120 moh. Bildene er tatt om ettermiddagen den 19. juli 2017.

Det er fritt frem å laste ned og å skrive ut kartet til utskrift og lignende.

Mulig det dukker opp flere slike bilder  fra Mindland i løpet av sommeren.