'a line crossing' is correct and usable in written English.
You can use it to describe a situation when something crosses a boundary or literal line. For example, "When the train crossed the state border, it marked the start of a new line crossing."
The line detection is done at the pixel level by determining whether a pixel belongs to a line crossing it along a particular direction.
We conducted measurements along a line crossing the scarp (line X in Figure 3a) to examine the heat flow variation with distance from the fault.
We quantified the signal intensity along a line crossing the plasma membrane (white lines in the Fig. 4d images).
The AS-OCT measurements were performed at the horizontal meridian in the center of the graft at a line crossing the pupil center.
For this, we extracted the fluorescent profiles for VGAT puncta and biocytin-loaded NG2 cells by tracing a line crossing both the puncta and the biocytin-loaded region.
The inclination of the acetabular component was measured using the angle between a line joining the ischial tuberosities and a line crossing the long axis of the acetabular component, determined by means of the axis of the major diameter that is formed by the apex of superior and inferior edges of the acetabular component on the radiograph [ 13].
"There clearly is a line crossed that I hadn't seen before".
In response, protesters waved flags showing a cartoon brain with a line crossed through it.
In the distance a line crosses the vast stretch of the river, but it appears to be flapping.
Political candidates and officeholders can be expected to accentuate the positive and minimize the unseemly; but was a line crossed?
His manuscripts, which I discovered in 1976, contain page after page of abstract mathematics and detailed calculations in physics and astronomy, with hardly a line crossed out.
