Accuracy of the GeoBase 2005-2010 data set
The ortho-rectification process of SPOT 4 and SPOT 5 imagery results in orthoimages with a high degree of positional accuracy. Figure 1 shows the positional accuracy of the orthoimages produced since the beginning of the GeoBase 2005-2010 project until now. Note that more than 98% of the orthoimages are accurate to 30 metres or better within a 90% confidence level (of precision).
Tests to determine accuracy were carried out by measuring the difference in X and Y coordinates between the same control points found on overlapping images. Based on evenly spaced samples taken from across Canada, Figure 2 shows mean differences and standard deviations of less than 10 metres. These factors are particularly important to those wishing to create mosaics of all of Canada or of regions of the country.