there is a line distortion between two faces in android 5.1 and opencves 3.1 about transform360

[evgenykuzyakov]

Please add more details with screenshots. It's probably related to expansion coefficient for each cubemap face.

[xuws20]

[xuws20]

it happens only in android5.1 and opengles 3.1. but in windows and opengles3.1 , there is no line distortion.
It happens only transparent and smooth area. In these areas, eyes are sensitive.
expansion coefficient is set 1.01 or 1.1, the problem still exist.
The face size is equal to 896.

[xuws20]

Problem has been already solved. Interpolation model is modified from GL_LINEAR to GL_NEAREST.Thanks.

[evgenykuzyakov]

It's probably not the interpolation that causes the seam to be visible. Something is off with UV coordinates. The correct padding for rendering is (1.0 - 1.0/expand_coef) * 0.5 from each side of each face. So if expand_coef is 1.01, the padding should be 0.5 / 101.0

[h4ck3r89]

Could you share how you set this up? The steps you followed to build transform360 and the OS and 32bit/64bit version details?

Thanks..:)

[xuws20]

you are right。After the interpolation mode is changed, image quality is getting worse。
expand=coef=1.003，off_x = (1.0 - 1.0/expand_coef) * 0.5 /3.0f,off_y=(1.0 - 1.0/expand_coef) * 0.5 /2.0f

[evgenykuzyakov]

expand_coef=1.003 is probably too small for 896. Since you're likely using yuv420, you need at least 2 pixels from each side of the face to avoid color seams. And this assumption ignores compression artifacts, which are not as obvious.
So you need 1 + 4 / 896=0.00446428571. Try using expand_coef=1.005

[evgenykuzyakov]

Ok, closing for now. Reopen if you need more help.