The sub-cloud in the upper half (circles) of Figure 1.12 corresponds to the true bank notes. As noted before, this separation is not distinct, since the two groups overlap somewhat.

Figure 1.12. 2D scatterplot for X5 vs. X6 of the bank notes. Genuine notes are circles, counterfeit notes are stars. MVAscabank56.xpl

Вот еще нашел часть из контекста про sub-cloud
The sub-cloud in the upper half (circles) of Figure 1.12 corresponds to the true bank notes. As noted before, this separation is not distinct, since the two groups overlap somewhat.

Average number of rooms per dwelling X6
The number of rooms per dwelling is a possible measure for the size of the houses. Thus we
expect X6 to be strongly correlated with X14 (the houses' median price). Indeed|apart from
some outliers|the scatterplot of X6 vs. X14 shows a point cloud which is clearly upwardsloping
and which seems to be a realisation of a linear dependence of X14 on X6. The two
boxplots of X6 con rm this notion by showing that the quartiles, the mean and the median
are all much higher for the red than for the black boxplot.

point cloud плотное множество точек (напр. при сканировании), точечное множество (Лингво)

Мне кажется этодолжен быть какой то другой тип точек. Но сново же контекст.