Explanation:

Angle Calculations

Steepest Faces

Peak Lists:

Canadian Summits

Alberta Summits
British Columbia Summits
Yukon Summits

External Links:

Listsofjohn
ORS(Spire Measure)
Prominence
Google Maps

Summit Analysis using Geobase Canada

Canadian Summits

Welcome to the Canadian section of NED-FILES. Analysis is being developed for British Columbia, Alberta, and the Yukon, with the remaining provinces being of lower priority. The same 3 criteria as the US lists will be used (maximum, greatest minimum, average). Analysis distances are set at 200m, 800m, 1600m. For a dry discussion of the differences between the US and Canadian lists, see the article below.

For a couple early BC samples(not error checked) see:

49N 120W-50N 122W
49N 124W-50N 126W


Variations in Digital Data and Analysis Methods

Despite the same analysis criteria(maximum, greatest minimum, average), there are a couple of differences in assessing Canadian summit steepness compared to the US.

Digital data is supplied by Geobase Canada. Highest resolution available is .75 arc seconds(21.75m squares), thus the smallest distances analyzed for Canadian Summits has been set at 200m. The US lists on this site use a .33 arc second resolution(10m squares) with a minimum analysis distance of 100m.

Peak lists are taken from bivouac.com. Unlike the comprehensive and accuarate summits list available for many US states(see listsofjohn.com) there is no minimum prominence threshold to the bivouac lists, and hundreds, if not thousands of summits at a P500 and P300 level are ommitted. In addition, many of the coordinates provided by the bivouac lists are approximate - not a big deal when visually identifying the location of a given summit on a map, but a major problem when running steepness numbers, as calculations need to be made from the exact summit location. Elevations of many of the peaks, even major ones, tend to vary as well, with the bivouac lists often being in disagreement with other sources and what is shown on the maps.

As far as missing summits go, little can be done until more comprehensive lists for Canadian peaks become available. This is hardly a criticism of the bivouac lists, as mapping the summits in a mountainous territory such as British Columbia at a P300 level would be a huge task. So the summit lists used on this site are admittedly incomplete.

Steepness analysis from a bad summit location is not valid, so inacurrate summit coordinates cannot be overlooked. Similarly, major discrepancies in summit elevations must be resolved to provide an accurate assessment. To correct these problems, whenver there is a discrepancy in location or elevation between the bivuoac lists and the DEM, maps, or other sources, summit elevations from DEM readings are used. Innaccurate summit locations are resolved by finding the highest DEM reading in a 400m radius around the bad summit location, in order to find the "true" summit location as the digital model regards it to be.

An example of this fix: Slesse Peak has a listed evelation of 8000', and a listed location of 49.02555,-121.59194. The DEM reading at the listed location is 5660', 2200' lower than the listed summit! Obviously this location is not the summit as far as the digital data is concerned, and indeed plotting the listed summit coordinates on a map puts the summit on Slesse's E slopes. Other sources turn up a summit location of 49.025494,-121.597474 and an elevation of 7969'. The digital elevation data turns up a summit location of 49.02576662,121.5980979 with a listed elevation of 7814'. Which to use?

Given the number of location discrepancies on the Bivouac lists(hundreds) it's impractical and inconsistent to manually refer to different sources to obtain revised elevations for each of these summits. The next best thing is to use the DEM elevations and locations. The location that results from a DEM search is often accurate when later plotted on a map. However, the summit elevations given in the DEMs are regularly lower than the listed elevation, sometimes by as much as 200'. As is the case in the US, DEMs(other than perhaps those taken from Lidar) are not reliable as sources of exact summit elevations compared to elevations ontained from maps or surveys. However the DEMs are generally accurate in providing relative elevations, which is what is required by steepness analysis. In the case of Slesse, the DEM gives 7814 summit elevation at its corrected location. Though likely not its true elevation, this figure is effective for steepness measurment since the DEM readings for the terrain surrounding the summit will be accurate relative to the DEM summit elevation.

Thus in contrast to the US lists, all Canadian summits use DEM summit elevations. Summits whose coordinates had to be singificantly modified from what was listed on the bivouac lists are shown in red.

Work on the Canadian summits project will be proceeding by rectangular areas of 2-4 square degrees. Given the number of summits which need to have their locations and elevation revised, progess will be slow and the likelihood of errors in steepness numbers, at least in the early stages of the process, will be much higher than with the US lists.

This site still a work in progress.

 


 
Text Copyright Tim Worth, 2007-2010.
Email: tim.worth5 (AT) gmail (DOT) com
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