It might be because they are either on the exact same layer or a layer behind the image. If you sketch on a layer or workplane in front of the image, you then may be able to see them. I've never used Catia though but its just a thought.
Those lines appear on the plane of the picture by default i changed the transparency to make it visible.
I agree with Jonathan. It looks like the image is in front of the sketch. Rotate the view 90° and see where everything lays.
Is there an option in Catia to change the transparency of the image? You might then be able to see through it.
yes. we can change transparency in picture properties, now the lines are visible.
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