The tomographic approach which basic unit is rectangular block can model and inverse the complex velocity structure.

这种层析反演方法以块体为基本单元，可以模拟和反演复杂速度结构。

youdao

With the sets of basic specifications and features set in stone, HTC's engineers can then offer the right phone sizes that meet the carriers' requirements, as well as showing a relatively bland rectangular ABS block as an indication on how much space is needed to pack all the components.

ENGADGET: HTC talks smartphone design: from inception to final product

At the Frequencies media summit in Seattle over the last two days, HTC walked us through the fine details on how its smartphones are developed, going from the boring rectangular ABS block to the more refined plastic mockups that are presented to carriers and focus groups -- the findings of which then shape the final product.

ENGADGET: HTC talks smartphone design: from inception to final product

This rectangular, windowless block grabs attention with its vertically-aligned tile work -- all in white -- which creates a rich texture when it catches the sunlight.

BBC: An Alvar Aalto tour of Finland