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

asked Feb 26 '17

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 Feb 26 '17

Eduardo gravatar image

updated Mar 27 '17

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: Feb 26 '17

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Last updated: Mar 27 '17