Hello, I thought I'd just update folks with my progress, I am using symbolic computation to compute the need jacobian, with sympy:
http://nbviewer.ipython.org/urls/gist.githubusercontent.com/blowekamp/359f7d2e5221eae97a1b/raw/dd5614577474dc6b012406a238e702468c886e0b/ScaleSkewJacoboan.ipynb Looks a bit hairy... Brad On Dec 12, 2014, at 12:11 PM, Bradley Lowekamp <blowek...@mail.nih.gov> wrote: > Hello, > > This seems very wrong to me... > > I was looking into the inverse of the classes. And I saw how the matrix was > composed from the scale and versor components[1] > > newMatrix[0][0] = m_Scale[0] - 2.0 * ( yy + zz ); > newMatrix[1][1] = m_Scale[1] - 2.0 * ( xx + zz ); > newMatrix[2][2] = m_Scale[2] - 2.0 * ( xx + yy ); > newMatrix[0][1] = 2.0 * ( xy - zw ) + ( m_Skew[0] ); > newMatrix[0][2] = 2.0 * ( xz + yw ) + ( m_Skew[1] ); > newMatrix[1][0] = 2.0 * ( xy + zw ) + ( m_Skew[2] ); > newMatrix[1][2] = 2.0 * ( yz - xw ) + ( m_Skew[3] ); > newMatrix[2][0] = 2.0 * ( xz - yw ) + ( m_Skew[4] ); > newMatrix[2][1] = 2.0 * ( yz + xw ) + ( m_Skew[5] ); > > Similarly both classes just add the scale/skew component and don't do correct > matrix composition. > > Let R be the versor, S scale, and K skew matrices, and p be a point. > > Currently we have: > > (R+S+K)*p = R*p+S*p+K*p > > Where I expected these classes would be implementing: > > R*S*K*p > > which is a traditional composition of transform matrices. > > Anyone know where the current math came from? Or what it's really doing? > > Is this something that we should fix/improve/evaluate? Or just document > what's actually happening? > > Brad > > > > > [1] > https://github.com/InsightSoftwareConsortium/ITK/blob/master/Modules/Core/Transform/include/itkScaleVersor3DTransform.hxx#L219-L227 > _______________________________________________ > Powered by www.kitware.com > > Visit other Kitware open-source projects at > http://www.kitware.com/opensource/opensource.html > > Kitware offers ITK Training Courses, for more information visit: > http://kitware.com/products/protraining.php > > Please keep messages on-topic and check the ITK FAQ at: > http://www.itk.org/Wiki/ITK_FAQ > > Follow this link to subscribe/unsubscribe: > http://public.kitware.com/mailman/listinfo/insight-developers _______________________________________________ Powered by www.kitware.com Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html Kitware offers ITK Training Courses, for more information visit: http://kitware.com/products/protraining.php Please keep messages on-topic and check the ITK FAQ at: http://www.itk.org/Wiki/ITK_FAQ Follow this link to subscribe/unsubscribe: http://public.kitware.com/mailman/listinfo/insight-developers
