Convert ETS to GBR

Technical note

ETS to GBR: what carries over and what does not

ETS is made of pixels and GBR stores geometry, so the conversion traces the image into real lines, arcs and polylines. The result is editable in CAD: entities can be selected, snapped to and measured, rather than a bitmap wrapped inside a GBR container, which is what a viewer or a lightweight converter usually produces. It is still derived geometry, so expect contours rather than a structured drawing. Dimensions, blocks and meaningful layer names were never in the ETS to begin with. A ETS file has a pixel count and a DPI value, and no real-world size at all. GBR is a drawing where one unit means one millimetre or one inch, so the conversion has to assign a scale. Set the DPI before the run rather than resizing afterwards, then measure one feature of known length in the output and scale the drawing once to match it. Everything downstream, from dimensioning to cutting, rests on that single check.