What are the light blue lines on my imported objects

Question

So recently, I have been noticing neon light blue lines on objects I import, in place of the the normal orange selection lines. Maybe I was supposed to be getting this variant of line before hand or maybe I just somehow haven't noticed it till now. But assumptions aside, I'm wondering what this line is for and how can I get rid of the light blue lines? Also Along with this my objects that are imported seem to have their faces turn from gray to white.

Answer 1

This means in Shading/UVs those edges have been marked as Sharp:

The Sharp mark is used by the split normals and the Edge Split modifier, which are part of the smoothing or customized shading techniques. As seams, it is a property of edges, and these operators set or unset it for selected ones.

See the manual: https://docs.blender.org/manual/en/latest/modeling/meshes/editing/edge/edge_data.html#mark-sharp-clear-sharp

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As for clearing sharp edges, open up the Edge menu (CtrlE) and select Clear Sharp:

In 2.7 versions, this can be done here from the Tool Panel T > Shading:

But this UI doesn't appear to be supremely intuitive (October 2015). it seems you have to click Sharp first before that panel becomes visible.

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Here's a script that lets you

• Mark selected edges as sharp
• Or remove sharp status of a set of selected edges

Code for Object Mode:

import bpy

obj = bpy.context.object
for e in obj.data.edges:
    if e.select:
        # invert current state
        e.use_edge_sharp = (not e.use_edge_sharp)

Answer 2

Select all edges and press Crtl + E Clear Sharp and Mark Sharp are under Mark/Clear Seam.

Answer 3

For Blender 2.8+ you can toggle the visibility of marked edges under the drop-down Overlays at the top of the viewport.

Toggle the Sharp option.