Micro-satellite constellations: use in Forestry
There is a large number of Earth imaging satellites with high to very-high resolution cameras.
The cell-size of their images generally ranges between 30 cm and 1 m . This is sufficient to map the smallest features in a cutblock.
Figure 1. False-color view of cutblock in Central British Columbia [PlanetScope, PlanetLabs image].
Micro or miniaturized satellites are smaller than one cubic foot and weigh around 1kg.
Very large constellations of micro satellites have the capacity to image the entire Earth very frequently (daily).
The PlanetScope Dove micro-satellite constellation, for example, provides optical imagery between 3 m and 4 m in ground sampling distance (distance between image pixels/cells).
That resolution is smaller than that of the most recent SPOT satellites (1.5 m panchromatic band) but is significantly better than the imagery from Sentinel-2 (10 m panchromatic band).
The imagery from micro-satellite constellations generally costs a few U.S. dollars per sq. km. That is significantly cheaper than the data from higher resolution satellites such as SPOT and WorldView. Very-high-resolution satellite imagery typically costs USD10-17 per sq. km for base products. Additionally, the temporal resolution of very high resolution satellites such as WorldView-3 may translate into only a few images per year for a certain area.
Is micro-satellite imagery useful for post-harvest cutblock forest cover mapping?
Figure-1 displays portion of a cutblock just to the north of Cheslatta Lake, in Central B.C., Canada.
The pink tones generally reflect bare-ground and areas logged a year or so ago; the dark greens indicate mature forest; and the bright greens are associated with short vegetation. Grayish to brownish tones were logged recently.
Therefore, it appears that this type of medium-high resolution imagery is not able to support a detailed forest cover mapping.
Positive traits for post-logging cutblock forest cover mapping:
1) on-block roads are generally sharply differentiated;
2) positional accuracy of orthorectified imagery is acceptable.
What about other uses in forestry?
Among other potential uses, the combined medium-high resolution, daily revisitation time of this type of imagery may be useful for:
1) providing rapid information for natural hazard response, management , and monitoring, particularly in remote regions;
2) supporting compliance tracking for tenured operations in Public/Crown forest management area;
3) potentially, identify other illegal activies in Public/Crown forest.