Saturday, 28 April 2018

"Horses for courses", part II

previous post here contrasted full professional workflows for petroleum geology students, with very simple analytical tools for a businessman looking to ascertain population density. As my subsequent posts show, I have an interest in Antarctic and Arctic maps, history and climate; you can see my case against the popular web Mercator for polar regions in this map story.

Facebook group Remembering the Franklin Expedition had an interesting post about a monument on Beechey Island, the overwintering camp of the doomed 1845 expedition seeking the Northwest passage. I found it in Wikipedia & Wikimedia and is described in detail by Parks Canada:

Beechey Island 01 1997-08-02
Mouse-over for attribution

Sleuthing

So how does one place an oblique photo like that in its geographic context, for people with geographic knowledge but not necessarily any mapping expertise? I looked for free & easy software and found two: I started with Google Earth, which can post oblique photos as overlay images. But its base imagery is pretty coarse for the large scale / close-in mapping required by an aerial photo.

Axis maps

This is an amazing piece of kit - it helps create contour maps from pre-existing global digital elevation models - and this will enhance the impression of relief on a region that is pretty flat: The Canadian Arctic Islands exist on two levels, coastal and atop 1000 ft cliffs - think of it as fjord land, where the mountains have been eroded down to almost sea level - this is a general view of the region and a detailed contour map of the island.

Google Earth view of Beechey Island, off SW corner Devon Island


Axismaps 1 m. contour for Beechy Island at Google level 14 zoom

Google Earth

 GE gives you two options: view directly in a Chrome browser, or download the app that allows you to load your own files and overlay your images. Please use the latter if you wish to do this, and the detailed workflow will be posted soon.

Oblique photo as image overlay
The oblique image above has no spatial reference, as it was taken 20 years ago before digital cameras and geo-tagging. Both Wikipedia and Parks Canada have enough images that the location and azimuth of the photo could be guessed roughly, close enough to place it on Beechey Island. The ruins are those of Northumberland House that is geo-located on Wikipedia. It's then a matter of orienting oneself on Beechey Island using Google Earth imagery and relief, and the contour maps just generated in Axismaps - load it in QGIS also free and save it as KML files to post directly in GE - while 1 m. interval are shown above for eye-candy, 10 m. contours are posted on my Google placemark, as is the photo overlay. Below, the contours 'disappearing' below imagery is a classic case of mismatched datums & projections that don't drape contours over imagery.


Beechey Isl. with memorial site to the left


GE is not great for sharing, it only offers facilities to email place-mark - please comment below if I'm wrong - so I posted them and the whole data set under CC BY-SA 3.0 on Google Drive. Also created a YouTube video of same:


 

Serving

Stay tuned for PArt IIa that shows this in ArcGIS Online, with a little more kit involved.


Thursday, 29 March 2018

Historic climate data revisited, circum-Arctic

[Note: watch this story map on follow-on class materials the last two blogposts generated

Go also to para.5 of 1000 GIS applications ]

Following on the Antarctic blogpost, I took my lessons-learned to the antipodes for these reasons:

Wednesday, 21 March 2018

Historic climate data revisited, circum-Antarctic

[Update: please see a mirror project in the Arctic here.]

With ongoing debates whether Antarctic ice in increasing or not, and its effect on climate change, we must avail ourselves of as much data as we can. If historic climate data is at hand, not only do they get scarcer going farther back, but 1880 also marks a time prior to which their reliability falls off.

So having mapped climate data off tall ships captains logs from 1750 to 1850, I wondered how far south they sailed, and how much they augmented historic climate data around the Antarctic?

Friday, 16 March 2018

"Qui peut le plus, peut le moins" or "Horses for courses"

These quips mean that, while we may have great tools for complex workflows, such as Mapping Well Data I'll present as AAPG Visiting Geoscientist in Hungary next month, sometimes it's better to pare it down to its simplest form, such as for a friend "looking to map addresses to [a French geographic subdivision]".

Friday, 2 March 2018

Development of Spatial Grids and...

The Association for Geographic Information Geocom2017 gathered at the Geographical Society in London late last October. Its Lightning Talks showcased new ideas and businesses. I was invited there to challenge attendees "to think about the development of spatial grids and the structure of spatial data models". The presentation itself and thank-you letter were followed by a short report in GIS Professional scanned here:

Tuesday, 20 February 2018

GDPR revisited

I already wrote about GDPR from the perspective of helping users get started with using Mind Maps. The presentation wraps up with further help from LINQ I partnered with.

Thursday, 18 January 2018

My adventure with Storm Fionn

As Storm Fionn wrought chaos in England and Cambridge, here's my adventure in returning a rental car this morning.