from the article "The full data set consists of roughly 8,000,000 points in E9. By normalizing with respect to mean intensity and restricting attention to high

from the article "The full data set consists of roughly 8,000,000 points in E9. By normalizing with respect to mean intensity and restricting attention to high-contrast images (those away from the origin), the data set is projected to a set of points M a topological seven-sphere S7 ⊂ E8" http://www.math.upenn.edu/~ghrist/preprints/barcodes.pdf http://www.math.upenn.edu/~ghrist/preprints/barcodes.pdf