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OpenKinect / libfreenect2

Open source drivers for the Kinect for Windows v2 device
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Warped pointcloud near corners #319

Open robinJKU opened 9 years ago

robinJKU commented 9 years ago

Hello,

I have a strange issue regarding my kinect2, when facing down about 45° at a table I get a warped pointcloud, it looks pretty much the same with and without calibration. I calibrated the kinect using a checker board with nearly 200 images.

Setup: Image of Problem Pointcloud: Image of Problem

Is this a ToF issue or is it possible to fix the problem?

JoshBlake commented 9 years ago

This looks like the interior corner reflection artifact common to ToF sensors. The laser pulse illuminates the scene, but the diffuse surfaces sometimes reflect the pulse back across multiple bounces (off the checkerboard, then off the table, then to the sensor, or table then checkerboard). This input is added to the true single-reflection data and is smoothed within the sensor stack to give you that warped surface.

There isn't much that you can do unless you want to post-process the data manually, or change the scene geometry to avoid interior corners, or change the scene materials to have at least one un-desired interior plane use a darker fabric to absorb more of the IR pulse reflection.

Joshua Blake Co-founder & VP of Engineering Orbbec http://www.orbbec3d.com

(cell) 703-946-7176 Twitter http://twitter.com/joshblake | Blog http://nui.joshland.org

On Tue, Jul 14, 2015 at 12:21 AM, robinJKU notifications@github.com wrote:

Hello,

I have a strange issue regarding my kinect2, when facing down about 45° at a table I get a warped pointcloud, it looks pretty much the same with and without calibration. I calibrated the kinect using a checker board with nearly 200 images.

Setup: [image: Image of Problem] https://camo.githubusercontent.com/9a2ca8f9ac63536046d1e96a2dd1ebab3347d814/68747470733a2f2f7069636c6f61642e6f72672f696d6167652f696961636961632f323031352d30372d313331312e35302e35312e6a7067 Pointcloud: [image: Image of Problem] https://camo.githubusercontent.com/0621bd034123ab644a41ae3db05c5743acd33f89/68747470733a2f2f7069636c6f61642e6f72672f696d6167652f6969616369616f2f706f696e74636c6f75642e706e67

Is this a ToF issue or is it possible to fix the problem?

— Reply to this email directly or view it on GitHub https://github.com/OpenKinect/libfreenect2/issues/319.

robinJKU commented 9 years ago

Thanks for your reply, I already tried moving the table away from the wall and get the same result.

floe commented 9 years ago

If it's not a ToF hardware issue, then it might be related to #144 - do you have an Windows 8 machine at hand and could try to extract the xTable/zTable offset maps from the GPU?

cnanda-zbr commented 8 years ago

This is the effect of multipath.