The situation is more complicated when a tomogram has been squeezed more in Z than in X and Y. In this case, the Z-scale needs to account for both this differential squeezing and the section thinning. The line Z/X pixel size ratio will show the amount of scaling needed because of the differential squeezing. If you select Set incremental Z-scale then the Added Z-scale text box will be enabled instead of the Total Z-scale text box, and you can enter just the scaling needed to account for thinning.
The Draw model checkbox toggles model drawing, just as the t hot key does.
The Resolution text box determines the spacing between successive points when adding points continuously while holding down the second mouse button. Points will be added at the given interval for image zooms between 0.75 and 1.5, and at proportionally bigger or smaller intervals for zooms lower or higher than these values, respectively.
The Pixel size text box allows you to set the pixel size of the model, which is needed for extracting quantitative information. Enter a number then the units of measurement. Available units are km, m, cm, um, nm, A, and pm. When a new model is created in 3dmod, this pixel size will be initialized from the pixel spacing in the image file header if the spacing is different from 1.