Intermediate dimensions under self-affine codings

Intermediate dimensions were recently introduced by Falconer, Fraser, and Kempton [Math. Z., 296, (2020)] to interpolate between the Hausdorff and box-counting dimensions. In this paper, we show that for every subset $E$ of the symbolic space, the intermediate dimensions of the projections of $E$ under typical self-affine coding maps are constant and given by formulas in terms of capacities. Moreover, we extend the results to the generalized intermediate dimensions in several settings, including the orthogonal projections in Euclidean spaces and the images of fractional Brownian motions.