I just attended a fascinating presentation with the unprepossessing title of "CCRS/NRC/McGill Scientists - TOPICS OF PEATLANDS AND THE MER BLEUE BOG."* This was about a new project called*
MBASSS initiated by scientists from the Canada Centre for Remote Processing (CCRS), National Research Council (NRC), and McGill University to acquire airborne hyperspectral imagery and ground-based measurements for the purpose of validating satelllite optical earth observation (EO_) multi-hyperspectral data products for northern/subarctic peatlands.*
The world has about about 3 million square km of northern boreal peatlands, which are huge carbon stores.* About one million square km of these are in Canada.**Peatlands act as both a carbon source and a carbon sink in the terrestrial carbon cycle. The net effect of northern peatlands is a small to moderate carbon sink, removing an estimated 49 billion kg/yr (Tg/yr) of carbon from the atmosphere.
75% of these peatlands are bogs and one of these is
Mer Bleue a 28 square km bog very near to Ottawa.* Since it is much easier to study a bog that is 13 km from Ottawa than to travel a thousand km to subarctic Canada, Mer Bleue, which already has a peatland observatory, was chosen for the study.*
Mer Bleue is normally a net sink for carbon, removing on average 60 grams of carbon per square meter per year (g C m-2 yr -1), but this can vary from year to year depending on factors such as water level.* Historically it has ranged from 10 to 128 g C m-2 yr -1.
Conventional overflights for the project are being conducted by the NRC using a fixed wind aircraft (Twin Beaver).* But as an alternative, Matt Maloney of CCRS has conducted trial flights with three different UAVs.* At the low end with a Phantom 2 equiped wiith a GoPro camera.* The other devices are a Spider PX8 and an Aeromapper EV2 with a Sony camera.* He had to get Transport Canada Flight Certification which requires line of site and daylight only and less than 300m altitude operation.* The area covered by the UAV flights was 500 square meters.
He used a technique called
structure from motion which takes the 2D images captured by the UAV and stitches them into point clouds, ortho mosaics, and digital surface models.* By way of comparison with a typical fixed wing overflight equiped with LiDAR which typically generates two points per square meter, the point clouds captured from the UAV have a density of 500 points per square meter.* The ortho mosaics and digital surface models captured with the UAVs (and using ground control points)were quite impressive with 3-5 cm pixels and rmse less than 5 cm.
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