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Can value of objectPoints for solvePnP ranging from 1.0 to -1.0?

asked 2017-02-25 21:47:05 -0500

yorkhuang gravatar image

Does anyone know the constraint of value of objectPoint list for solvePnP? I normalize each axis of 3D value of objectPoint for solvePnP() ranging from +1.0 to -1.0 before input to solvePnP function. Is it OK to have this type of 3D value setting? Will this setting cause any problem?

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answered 2017-02-26 09:34:49 -0500

Eduardo gravatar image

updated 2017-03-27 12:24:40 -0500

No you don't have to normalize the values for objectPoints. If you do it, the translation should be estimated up to a scale factor.

The common requirements are:

  • the x, y, z components must be expressed in the same units
  • the minimum number of points is 4 to estimate correctly the camera pose
  • the 3D points should not be collinear

I think that some configurations could lead to singularities or camera pose badly esimated or completly wrong. For instance, if all the imagePoints are projected almost on a same line (with 4 coplanar 3D points for instance)?

Edit:

I found an interesting course, "The Perspective View of 3 Points" by Bill Wolfe, which give the following information:

P3P

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Asked: 2017-02-25 21:47:05 -0500

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Last updated: Mar 27 '17