B-scan transverse (horizontal) scale (microns/pixel)

[Jason Kugelman]

Hello,

Is there currently any knowledge about the existence of this value (or a similar one) within the E2E file. To clarify further, this is the transverse scale of each individual b-scan (across the width of the scan). It appears this value exists for the axial scale (down the scan) (scaleY in E2E/dataelements/bscanmetadataelement.cpp) the value of which is as expected. However, there does not seem to be an equivalent scaleX? A full brute force search (of every possible float32 value, stepping byte by byte) of the file finds this scaleY value for each bscan but does not reveal the scaleX value (note the value for scaleY matches precisely with that obtained from a corresponding .vol file). Searching within a small range (i.e. with a tolerance) either side of the expected scaleX value also does not yield success.

Any ideas of how to obtain this value from the E2E file or how or where it might be stored?

[kaygdev]

Hello jakugel,

it seems that the value is not saved in μm/pixel in the E2E file. The start and end coordinates of each B-scan are given in degrees. From this information, the searched value can be calculated if the distance to the origin (eye length?) is known. Unfortunately I could not find the latter value, so LibOctData is coded with a fixed value. A value in degrees seems to be better, because μm/pixel should not be constant in depth.

Best Kay