hom_mat3d_compose

Herror ::hom_mat3d_compose ( const HTuple &HomMat3DSecond, const HTuple &HomMat3DFirst, HTuple *HomMat3DCompose )

Compose two homogeneous 3D transformation matrices.

::hom_mat3d_compose composes a new 3D transformation matrix from the two input matrices. The transformation given by HomMat3DFirst is applied first, followed by the transformation given by HomMat3DSecond, i.e., with HomMat3DFirst = H_1, HomMat3DSecond = H_2, and HomMat3DCompose = H_c is:

H_c = H_2 H_1

A homogeneous 4x3 transformation matrix describes the transformation of a 3D point from the source coordinate system into the destination coordinate system. In this sight the following holds are usable:

/ x3 \       / x1 \           / x1 \
| y3 | = H_g | y1 | = H_2 H_1 | y1 |
\ z3 /       \ z1 /           \ z1 /

             / x2 \
       = H_2 | y2 |
             \ z2 /
with:

/ x2 \       / x1 \       / x1 \
| y2 | = H_1 | y1 | = R_1 | y1 | + T_1.
\ z2 /       \ z1 /       \ z1 /

therefore:

/ x3 \       / x2 \             /     / x1 \       \ 
| y3 | = R_2 | y2 | + T_2 = R_2 | R_1 | y1 | + T_1 | + T_2
\ z3 /       \ z2 /             \     \ z1 /       /

                 / x1 \    
       = R_2 R_1 | y1 | + R_2 T_1 + T_2
                 \ z1 /

             / x1 \
       = R_c | y1 | + T_c       
             \ z1 /
with:

Rotation R_c = R_1 R_2 and
Translation T_c = R_2 T_1 + T_2

Parameters

`HomMat3DSecond` (input_control)	affine3d-array `->` HTuple.double
Second input transformation matrix.
Number of elements: 12

`HomMat3DFirst` (input_control)	affine3d-array `->` HTuple.double
First input transformation matrix.
Number of elements: 12

`HomMat3DCompose` (output_control)	affine3d-array `->` HTuple.double *
Output transformation matrix.
Number of elements: 12

Example

HTuple Pose, HomTransMat1, HomTransMat2, HomTransMatMult ;
// read camera pose
::read_pose("campose.dat",&CamPose);
// transform pose to transformation matrix
::pose_to_hom_mat3d(CamPose,&HomTransMat1);
// multiply transformation matrices
::hom_mat3d_compose(HomTransMat2, HomTransMat1, &HomTransMatMult);

Result

::hom_mat3d_compose always returns H_MSG_TRUE.

Possible Predecessors

::hom_mat3d_identity, ::hom_mat3d_translate, ::hom_mat3d_scale, ::hom_mat3d_rotate, ::pose_to_hom_mat3d

Possible Successors

::hom_mat3d_translate, ::hom_mat3d_scale, ::hom_mat3d_rotate

Module

Basic operators