2016 Snowking Winter Festival XXI

March 1, 2016 – The Grand opening of the 2016 Snowking Winter Festival XXI. Check out the official Snowking Winter Festival webpage ….http://snowking.ca/

These are a couple of sneak peak images and panoramas from inside the castle and from the roof.

Yellowknife snowking

To view the 360 degree animation. Click Here. Use your mouse or swipe the screen to look around. This requires the QuickTime Player. Click the icon on the upper right corner of the animation to get a full view. Depending on network speed, the image may take a moment to load.

 

Yellowknife snowking

To view the 360 degree animation. Click Here. Use your mouse or swipe the screen to look around. This requires the QuickTime Player. Click the icon on the upper right corner of the animation to get a full view. Depending on network speed, the image may take a moment to load.

 

 

Yellowknife snowking
Yellowknife snowking

To view the 360 degree animation. Click Here. Use your mouse or swipe the screen to look around. This requires the QuickTime Player. Click the icon on the upper right corner of the animation to get a full view. Depending on network speed, the image may take a moment to load.

 

2016 Snowking Castle – Nearing Completion

Have a look around inside the 2016 Snowking Castle – it is almost Done !

DSCF5255 Panorama-2

Click Here for a Larger Image

To view the 360 degree animation. Click Here. Use your mouse or swipe the screen to look around. This requires the QuickTime Player. Click the icon on the upper right corner of the animation to get a full view. Depending on network speed, the image may take a moment to load.

 

2016 Snowking XXI Castle – in Progress

This is a quick n’dirty post – just to see if I can still remember how to photograph, generate and post 360 virtual reality panoramas.

Seems fitting in a way – as I haven’t done this in two years, and this image is of the yet to be completed snow castle for the 2016 Snowking Winter Festival in Yellowknife.

SHS_6458 Panorama-2

Click Here for a Larger Image

To view the 360 degree animation. Click Here. Use your mouse or swipe the screen to look around. This requires the QuickTime Player. Click the icon on the upper right corner of the animation to get a full view. Depending on network speed, the image may take a moment to load.

 

The NWT is on Fire !

At last count there are 130 forest fires in the Northwest Territories.

Check out the image below to see where they are.Canada.A2014183.1845.1km Satellite image from July 2, 2014.

Click here to go to the NASA webpage.

 

A couple of photos of Canadair Cl-215 water bombers that are being used to fight some of the forest fires, and a Beechcraft ‘Birddog’ airplanes for fire attach planning and flight safety.  The photos were taken in Yellowknife a couple of years ago while putting out a fire at the City landfill. All photos taken using a Nikon D700 and manual focus Leica Telyt 400mm f/6.8 lens with a Leitax adapter.

 

_SCH8551   _SCH8676 (2)    _SCH8765-2 (2) _SCH8781-2 (2) _SCH8831-2 DSC_9102-2 SHS_6935-2 SHS_6980

Twin Pine Hill – one of best places to enjoy a scenic view of Old town Yellowknife, and Great Slave Lake.

Twin Pine Hill – one of best places to enjoy a scenic view of Old town Yellowknife, and Great Slave Lake. These 360 degree panoramas were created from photos taken on May 18th, 2014.

In this view, Old Town is in the distance, to the north. Franklin Avenue (center of photo) separates Peace River Flats and Willow Flats (right side) and continues to Latham Island and N’Dilo in the distance. If you look carefully, the melted remnants of the Snow Castle can be seen, along with house boaters commuting across the ice, and a even a kite skier behind the houseboats.

Click on the image for a larger view.

To view the 360 degree animation. Click Here. This requires the QuickTime Player. Click the icon on the upper right corner of the animation to get a full view. Depending on network speed, the image may take a moment to load.

 

In this image, along the ridge to the southeast of the previous photo, Old Town (Willow Flats) is on the far left. The road winding up the hill is School Draw, an the remains of a recently burnt house can be seen in the center part of the photo.

Click on the image for a larger view.

To view the 360 degree animation. Click Here. This requires the QuickTime Player. Click the icon on the upper right corner of the animation to get a full view. Depending on network speed, the image may take a moment to load.

These panoramas were created by combining 5 photos (4 photos at 90 degrees to each other, and the fifth taken straight down at my feet to fill in a gap), using a Nikon D700, a ‘shaved’ Samyang 8mm lens with a custom built panorama head see Making Panoramas with a DIY Panoramic Head and a Monopole. The hardest part of making these panoramas was photoshopping out all the garbage and smashed bottles…

Making Panoramas with a DIY Panoramic Head and a Monopole

These notes describe the tools and technique that I use to create 360 and spherical panoramas. If you are interested in producing high resolution landscape or architectural panoramas – this is not for you as these types of panoramas require different tools (panorama heads, tripods and lenses). Check out the links below on tools and techniques to create high resolution and architectural (including interior) panoramas.

360 degree panoramas are best described as panoramas that cover up to 360 degrees in a single, super wide image, whereas Spherical panoramas can be described as the viewing of a seamless 360 degree panorama that is displayed on a interactive viewer (e.g. QuickTime VR, Flash or HTML5), and allows the observer (i.e. You) to interactively pan left or right, up and down and zoom in or out to look at the scene in different directions. The end result of spherical panoramas, is to give the observer the feeling of actually “Being there and looking around”.

The first step in making spherical panoramas is to create a seamless 360 photograph, that is wrapped in a sphere or cylinder. There are different methods to capture the separate photos that are stitched to create the seamless 360 degree image; ranging from more accurate (panoramic heads with lens specific clicks) to free hand (dangling a weight from a string over a specific feature on the ground). All methods require that the camera is rotated through an imaginary point ‘entrance pupil’ near the front of the lens to avoid (or minimize) visual off-set (parallax) when stitching the photos. Generally, the fewer images to stitch the less effect of parallax.

The tools that I use include a Nikon D700 camera, Samyang 8mm f/3.5 lens, a very simply DIY (make-it-yourself) panorama head, remote cable, and a monopole. Previously I did not use a panorama head, and simply mounted the camera to the monopole using the tripod screw on the base of the camera. This method works well as long there are no objects close to the lens (i.e. wide open areas), which cause parallax. Now, with a simple DIY panorama head (total cost approx. $10.00) there are fewer problems with parallax. Do note – that these tools and techniques work for me, and may not work for you, nor is this technique necessarily the correct or most accurate.

From top to bottom, I use the following camera gear and tools.

  1. Nikon D700
  2. Cable release
  3. Modified Samyang 8mm f/3.5 lens. I cut off the plastic lens hood to maximize the field of view. Similar lenses are sold as Rokinon and Bower.
  4. DIY panorama head (details on construction below).
  5. Manfrotto Bogen compatible umbrella swivel and Manfrotto 200PL-14 Quick Release Plate.
  6. Kacey adapter to mount the Manfrotto quick release to a standard paint pole type extension pole. The adapter has a 5/8 standard strobe pin on top and standard extension pole threads (3/4 x 5 threads per inch) on the bottom. Kacey website.
  7. Monopole (extendable painters pole), purchased at a hardware store.

Assembling the DIY Panoramic Head

My initial plan for a DIY panorama head was piece of metal plate that attached at one end to the camera tripod screw the the other end extending to the entrance pupil of the lens. However, the thought of the relatively heavy Nikon D700 bouncing up and down on the metal plate deterred that plan. Plans then turned to some way of attaching the front of the lens directly to the monopole. Then I found a muffler clamp. Sliding the muffler clamp over the entrance pupil of the lens – it was a close fit, and the U-shaped clamp only had to be widened by approximately 0.5cm. Scrap UHMW plastic was used to fill in gaps between the lens and the muffler clamp. A sheet of scrap metal (steel) was cut and drilled for the base, and two ¼ thread nuts are used to tighten the muffler clamp (finger tightened only). A coat of black automotive paint and adding the Manfrotto Quick Release Plate – then done !.

Total cost approx $10.00.

Note that the axis of rotation passes through the centre of the lens and the Nodal Point (entrance pupil).

Camera settings

These are the camera settings that I use;

1) File format set to ‘Raw’ 

2) Exposure mode set to ‘Manual’ – Set shutter speed minimum 1/30, aperture f/5.6 to f/10 depending on light conditions. Determine exposure for average light reading, not with lens pointed at the sun.

3) Set focus to manual

4) Set camera to full frame mode

Shooting Technique

To make my life easier, I always use the same lens and camera combination for spherical panoramas. With the shaved Samyang 8mm, I shoot four images each at 90 degrees apart (camera level).

  1. Camera settings as above
  2. Test photos of the scene to set exposure
  3. Walk to desired location, place the monopole on the ground. Remember the starting direction.
  4. Press shutter and rotate 90 degrees to the right (clockwise).
  5. Stabilize monopole, repeat 90 degree rotation and press shutter,
  6. Continue until back to starting point
  7. Done…walk away Click on the photo below to see it bigger.Depending on the scene, I might add two additional photos:
  8. Step back and take a Nadir shot (-90) by holding the monopole at arms length and point camera down to where the monopole was rotated in previous steps, at approximately the same height as the monopole, to create a foot-free image and,
  9. Take a Zenith or straight up (+90 degrees) shot  by tilting the camera up 90º (approximately over the rotation point), duck down, and shoot it. Zenith shots are only taken when in an enclosed space.

One I have the four (or six) photos, they are loaded into PTGui software to create the seamless 360 degree panorama and the spherical panorama. Check the links below for how to use PTGui software.  PTGui saves the spherical panorama as a Flash (.swf) movie that can be displayed on a website.

Examples of Flash (.swf) movies

A view of the inside of the Snowking’s Castle, during the 19th annual Snowking Winter Festival. Click on the image for a larger view.  To view the 360 degree animation. Click Here. This requires the QuickTime Player. Click the icon on the upper right corner of the animation to get a full view. Depending on network speed, the image may take a moment to load.
SCH_4251 Panorama-2-2
SCH_4478 Panorama-2
The view from the top of the Castle, and the “Deadman’s slide”. Click on the image for a larger view.

To view the 360 degree animation. Click Here. This requires the QuickTime Player. Click the icon on the upper right corner of the animation to get a full view. Depending on network speed, the image may take a moment to load.

 

Bullocks Bistro, in Old Town Yellowknife serves up the best fish in town, and is often featured on CBC Arctic Air.  Can’t think of too many restaurants that actually let you, and encourage you to leave your mark on the ceilings and walls !.

SCH_3491 Panorama-2_TM-TB Click on the image to see it bigger.
To view a 360 degree animation of this scene, Click Here. This requires the QuickTime Player. Click the icon on the upper right corner of the animation to get a full view. Depending on network speed, the image may take a moment to load.

 

Everyone’s favorite place to be on a hot sunny day….The Beer Garden (2012 Folk on the Rocks)

To view the 360 degree animation of “Snake People” in the Beer Gargen . Click Here This requires the QuickTime Player. Click the icon on the upper right corner of the animation to get a full view.

Frostbite 45 – A Northern Ski and Snowshow Event

Selected photos of frosted and frostbitten faces on participants can be seen on my Flickr page

The Frostbite 45 is a ski or snowshoe event held in Yellowknife. The course is 45 kilometers over windblown lakes and narrow skidoo trails between lakes. Participants can compete the entire course, or parts of the course as part of a relay team. This year, the 5th annual Frostbite-45 the weather conditions did not disappoint, with wind chill of -44C.
For the past couple of years I have volunteered at a Check Point; checking participant bib numbers and recording arrival times to help keep track of who is still on the particular section of the course, and when possible also photographing the other volunteers, skiers, runners (snow shoe participants can of often do remove their snow shoes on the hard packed trails). This year, I wanted to see the whole course, not only to get an idea what the participants see, and also to photograph the participants at different parts of the course. To do this – I used a skidoo, and it still took me six hours to compete the course.

The event, it is not called a ‘race’ started at 10am and the Yellowknife Ski Club with a 500 meter loop through the stadium area in front of the chalet (to spread out the group, and for the benefit of the spectators) then down the icy ravine onto Great Slave Lake. On the lake, it is approximately seven kilometers of directly in-you-face -40C something wind chill. I stopped a few times along this section to photograph the long stream of participants with the office towers of Yellowknife on the horizon. Already, at this point in the course, folks were getting cold. Even from a distance, I could recognize the circular motions of arms – trying to warm cold fingers, and hands on faces blocking the wind. There was even a fellow, with his hand in front of that part of the male anatomy. Time to move on.

Following a five kilometer skidoo trail through the forest must have given them some respite from the wind, until Walsh Lake – a long narrow lake perfectly aligned with the wind direction. The first Check Point, at the 15km distance is the one I know well. Shawne and Rauri were hard at work checking bib numbers and faces. By this point, most participants had covered up their faces with ski goggles, scarfs, neoprene face masks and neck warmers. Most were ok, although the strong wind has a nasty way of finding even the small areas of exposed skin such as the tip of the nose that normally pokes out at the bottom of ski goggles. Some were not as lucky, having small patches of white skin on reddened check. Others even less lucky with long stripes of frostbitten skin caused by wrinkles in their face masks, and one fellow who as first was thought to have a pale completion and this turned out to be a face of nasty frostbite. Needless to say, his race was over as the First Aid folks did not let him continue. As participants came through the Check Point I photographed some of them, forever recording those enthusiastic yet frost bitten faces.

The cold was also having an effect on my camera gear, and every few photos the viewfinder would stay black (the mirror had locked in the up position), and the LCD display read ‘err’. I now know what error message means, it is the cameras way of saying it is too darn cold and that the cameras normal operating temperatures range is no lower than 0C. A good time to leave the camera in my coat and let it warm up. By then, it was nearly 12:15, and in the distance back along the course we could see some participants had not yet completed the first section. For safety reasons, the Check Point is scheduled to close at 12:30, and those that had not yet past through the Check Point by that time would not be allowed to continue. It seemed like a good time to move on, as I did not want to be around or photograph the stragglers coming through after 12:30.

The course continues directly upwind to the end of Walsh Lake, then up over a hill and down to Prosperous Lake. From there I could see a long line of skiers and runners enduring a crosswind reroute to Check Point 2. Most of these folks I had already photographed at Check Point 1. Since my plan for the day was to photograph different participants at different parts of the course, I took a short cut and headed down wind towards Check Point 3 at the south end of the lake. On the way, I could see skiers and runners as tiny specks in the distance. Not far from Check Point 3, I noticed some incredibly scenic cliffs perfect to photograph the participants as they past in front. Not wanting to wait in the wind for the next skiers or runners to arrive, I sought shelter and found the perfect spot. There, out of the wind and actually being warmed by the sun were two volunteers from the Yellowknife Skidoo Club. We chatted and every 10 minutes or so I pushed down the visor of the skidoo helmet and peeked up wind to look for and photograph the next skier or runner as they passed by. Without the visor, the wind wanted to instantly freeze my eyes. Fortunately I had brought two cameras. The first was now completely dead. Even with extra batteries (I had bought 5 extra batteries) the LCD screen was blank. By 1:30 the second camera was starting to lock up and show the now all to familiar ‘err’ message on the LCD screen. A few photos later and it also went completely dead. Both cameras were now inside my coat – stone cold, and useless.

My job was to photograph the event, and by this point for most participants were still on the trails and had several hours to go before they completed the course. Without a camera, my contribution to the event was over. Being asked to retire from the event due to frostbite is one thing, as a photographer being forced to retire due to frozen cameras is another. By the time I got home at 4pm, not only were the two cameras still frozen, frost on the inside of my skidoo helmet had frozen my beard. A few tugs, and off came the helmet along with a tuft of beard hairs (just the grey ones right). My neck warmer had also frozen to my beard, tugging on it would have yanked out most of my beard hairs – outch. By 6pm I have thawed, the cameras have thawed (and are now working again), photos have been viewed, and I can’t help think about the folks that are still out there, the participants and volunteers.

Frozen cameras aside, it was again a rewarding experience to be a volunteer at Frostbite 45. This is however my last. Many participants in the Frostbite 45 have taken the time to stop, and say ‘thanks for helping’, then continue the course. Thanks folks. I would also like to thank the crew that organizes and sets up the event year after year; Shawne, Damain, Michael, Elaine (‘Master Tracker’, Tom, the volunteers at the Check Points, and the many clubs (Yk Skidoo Club, Amateur Radio Society), and all companies that provide products, services and people to make the Frostbite 45 a safe and successful event.

 

Selected photos of frosted and frostbitten faces on participants can be seen on my Flickr page

 

19th Annual Snowking Winter Festival (2014)

There is only one Snowking, see here wearing his trademark yellow jacket. As usual, Snowking was willing to pose for the camera, and simply walked into to the picture. Five pictures were combined to make this mosaic.

A view of the inside of the Snowking’s Castle, during the 19th annual Snowking Winter Festival.
SCH_4251 Panorama-2-2

 

To view the 360 degree animation. Click Here. This requires the QuickTime Player. Click the icon on the upper right corner of the animation to get a full view. Depending on network speed, the image may take a moment to load.

 

The Royal Courtyard. Click on the image for a larger view.SCH_4463 Panorama-2

To view the 360 degree animation. Click Here. This requires the QuickTime Player. Click the icon on the upper right corner of the animation to get a full view. Depending on network speed, the image may take a moment to load.

 

SCH_4478 Panorama-2
The view from the top of the Castle, and the “Deadman’s slide”. Click on the image for a larger view.

To view the 360 degree animation. Click Here. This requires the QuickTime Player. Click the icon on the upper right corner of the animation to get a full view. Depending on network speed, the image may take a moment to load.

 

SCH_4528 Panorama-2
The Ballroom, or call it what you want. This is where the bands play!!. Click on the image for a larger view.

 

To view the 360 degree animation. Click Here. This requires the QuickTime Player. Click the icon on the upper right corner of the animation to get a full view. Depending on network speed, the image may take a moment to load.

 

To view photos and 360 degree animations of the 2013 Snowking Winter Festival – Click Here.

For more info on the Snowking Winter Festival, Click Here

Camera gear: Nikon D700 and a Peleng 8mm lens on a custom monopole. Five pictures were combined to create the panorama image on this page.

Pilot’s Monument, Yellowknife

Pilot’s Monument is the best place to go for a scenic view of Yellowknife Bay, Old Town, with its unique character and Downtown Yellowknife (actually up the hill from Old Town). After climbing the stairs to the top of the hill, the view is spectacular. At the top there is a brass plaque as a tribute to northern pilots.

In this image, downtown Yellowknife is directly under the sun on the right side of the image. Pilot’s Monument is in the middle of the photo, and Back Bay is on the far left.

Click on the image for a larger view.

To view the 360 degree animation. Click Here. This requires the QuickTime Player. Click the icon on the upper right corner of the animation to get a full view. Depending on network speed, the image may take a moment to load.

 

Camera gear: Nikon D700 and a Peleng 8mm lens on a custom monopole. Six pictures were combined to create the panorama images on this page.

Documenting Land Cover and Vegetation Productivity Changes in the Yellowknife Area using the Landsat Satellite Archive

It is mid July, and you are motor boating through a myriad of islands on the way to your cabin. All is well until the prop hits a rock. You had been through this channel a million times before, and had never hit a rock. What’s Up ?. A few minutes later, as the boat rounds the last island before the cabin, you realise that the trees and shrubs look different. The cleared area in front of the cabin is now covered with shrubs, the shoreline is much farther back than it used to be, and the cabin is starting to sink into the ground !.  We all know that water levels change during the year, and that shrubs grow in cleared areas. Some of these changes could be just a natural part of a cycle, but what if they aren’t?.

To help understand, the causes and effects of these landscape changes, and if the changes that we are seeing on the landscape are part of a natural cycle or longer-term trend, a team of Federal, Territorial and University scientists are working on a project in the Yellowknife area. Using satellite imagery collected during the past 30 years, and remote sensing techniques we were able to visualize past and on-going changes to the landscape. One of the techniques, called Tasseled Cap Transformation, uses mathematical formulas to calculate values for brightness, greenness and wetness from a satellite image. Brightness represents a measure of reflectance from the surface; features such as bare soil, man-made, and natural features such as concrete, asphalt, gravel, rock outcrops, and other bare areas are considered bright. Greenness is a measure of vegetation; more vegetation is indicated by brighter green areas. Wetness is a measure of surface wetness including soil and plant moisture; wetter areas on the surface indicated by brighter colors on the satellite image. Satellite images spanning the 30 years of available data were analysed for landscape features that represent the Tasseled cap values for Brightness, Greenness, and Wetness.  Combining the Tasseled cap values from each separate satellite image, allows the long-term trends in the change of Tasseled cap values for Brightness, Greenness, and Wetness can be observed.  In Figure 1, the combined Tasseled cap values for Brightness are represented as shades of red, Greenness in shades of green, and Wetness in shades of blue, with brighter colors representing brighter, greener and wetter areas.

Figure 1

 

So, what do all the colors mean ?. Using field observations and photos taken from a helicopter, we are able to directly relate the trends (and colors) to observable and recognizable features on the landscape. A photo from the helicopter (Figure 2) over the circled on Figure 1, shows a small inlet with ring of brown vegetation (drying wetlands) and an inner ring of bright green vegetation (new vegetation growth). The combined Tasseled cap colors Brightness, Greenness, and Wetness for this area are yellow and green respectively, suggesting a trend during the past 30 years of yellow areas indicating drying up wetlands, and green areas where there is new vegetation growth.  Similarly, areas shown in pink (top left, Figure 1) are presumed to be non-vegetated shallow water areas including dried bogs (Figure 3). A photo of the old and new sections of Highway 3 (Figure 4), shows new vegetation growth on the old section, and paved, wide cleared area with no vegetation, corresponding to light blue and red areas on Figure 1. Areas shown in dark blue, are presumed to be the result of a change to a darker and a wetter forest.  The greenish color and banded pattern in the water is a by-product of processing of the imagery and can be ignored.

 

Figure 2
Figure 2
Figure 3
Figure 3

 

 

 

 

 

 

 

 

 

Figure 4
Figure 4

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Based on this work, we observed the two major trends shown in the Tasseled Cap Transformation:

1)    Apparent lowering of water levels along the shoreline of Great Slave Lake, and in nearby lakes, and shoreline vegetation appears to have expanded in bays. What is not yet fully understood, is the cause of the apparent lowering; it is due to lowering water levels and/or isostatic uplift (land rising after the weight of the glaciers has been removed). Most likely it is a combination of both.

2)      Apparent increasing treed vegetation (Dark blue areas on Figure 1). A working hypothesis to explain this trend is that growing conditions have changed such that it is now better for conifer trees such as spruce and jack pine. Additional research work is in progress to understand the increasing treed vegetation.

 

What do these trends mean in the long-term ?. Are some of these changes just a natural part of a cycle ?. Or – is there any reason to believe that these are the early part of a longer and continuous trend leading to a major climate shift ?.

The data used in this study used satellite imagery that is only available going back 30 years, and does not give any indication of what climatic and landscape changes were occurring in the region 60, 100, 500 or 1000 years ago. Without the long term record, not realistically possible to make long term predictions of the landscape changes into the future. In the short term however, we can predict that water levels will continue to lower and, if growing conditions have recently become better suited to conifer growth, there may be a successional transition from broadleaf forest (beech trees) to conifer trees.

In this project, we have shown landscape change trends in the Yellowknife area. For you, these trends might make it more difficult to navigate to your cabin, and how and where you build your cabin. More importantly, some of the trends in landscape changes observed via the Tasseled Cap Transformation may represent changes which cannot be directly observed. A trend indicating a transition to more-dominate to conifer may also affect the frequency and abundance of forest fires, and may also reflect a change (degradation) in underlying permafrost patterns. The impact of degrading permafrost may have a large impact on a wide range of infrastructure. Anyone who has driven Highway 3 (Yellowknife –  Behchoko) will certainly remember a few bumps in the road, the vast majority of which were caused by changes in the permafrost under the highway.

There probably isn’t too much that can be done locally to prevent many of the changes.  It is however, important to continue research to understand the underlying causes for the changes. Continued monitoring the changes, will provide useful information to decision makers, for example by showing which areas and terrain features are more sensitive and susceptible to change.

 

This work is conducted as part of and Natural Resources Canada’s project on Transportation Risk and Climate Sensitivity (TRACS).

Reference: Seventh International Conference and Workshop on the Analysis of Multi-temporal Remote Sensing Images (MultiTemp 2013), Banff, Alberta, Canada, June 25-27, 2013.

Fraser, R.H1, Olthof, I.1, Deschamps, A.1, Pregitzer, M.1, Kokelj, S.2, Lantz, T.3, Wolfe, S.4, Brooker, A.5, Lacelle, D.5, and Schwarz, S.6

 

(1) Canada Centre for Remote Sensing, Natural Resources Canada, Ottawa, ON

(2) Renewable Resources and Environment, Aboriginal Affairs and Northern Development Canada, Yellowknife, NWT

(3) School of Environmental Studies, University of Victoria, Victoria, BC

(4) Geological Survey of Canada, Natural Resources Canada, Ottawa, ON

(5) Department of Geography, University of Ottawa, Ottawa, ON

(6) NWT Centre for Geomatics, Govt of the Northwest Territories, Yellowknife, NWT