bundle_adjust_mosaicT_bundle_adjust_mosaicBundleAdjustMosaicBundleAdjustMosaic (Operator)

Name

bundle_adjust_mosaicT_bundle_adjust_mosaicBundleAdjustMosaicBundleAdjustMosaic — Perform a bundle adjustment of an image mosaic.

Signature

Description

bundle_adjust_mosaicbundle_adjust_mosaicBundleAdjustMosaicBundleAdjustMosaicBundleAdjustMosaic performs a bundle adjustment of an image mosaic. This can be used to determine the geometry of a mosaic as robustly as possible, and hence to determine the transformations of the images in the mosaic more accurately than with single image pairs.

To achieve this, the projective transformation for each overlapping image pair in the mosaic should be determined with proj_match_points_ransacproj_match_points_ransacProjMatchPointsRansacProjMatchPointsRansacProjMatchPointsRansac. For example, for a 2×2 block of images in the following layout

the following projective transformations should be determined, assuming that all images overlap each other: 1->2, 1->3, 1->4, 2->3, 2->4 and 3->4. The indices of the images that determine the respective transformation are given by MappingSourceMappingSourceMappingSourceMappingSourcemappingSource and MappingDestMappingDestMappingDestMappingDestmappingDest. The indices are start at 1. Consequently, in the above example MappingSourceMappingSourceMappingSourceMappingSourcemappingSource = [1,1,1,2,2,3] and MappingDestMappingDestMappingDestMappingDestmappingDest = [2,3,4,3,4,4] must be used. The number of images in the mosaic is given by NumImagesNumImagesNumImagesNumImagesnumImages. It is used to check whether each image can be reached by a chain of transformations. The index of the reference image is given by ReferenceImageReferenceImageReferenceImageReferenceImagereferenceImage. On output, this image has the identity matrix as its transformation matrix.

The 3×3 projective transformation matrices that correspond to the image pairs are passed in HomMatrices2DHomMatrices2DHomMatrices2DHomMatrices2DhomMatrices2D. Additionally, the coordinates of the matched point pairs in the image pairs must be passed in Rows1Rows1Rows1Rows1rows1, Cols1Cols1Cols1Cols1cols1, Rows2Rows2Rows2Rows2rows2, and Cols2Cols2Cols2Cols2cols2. They can be determined from the output of proj_match_points_ransacproj_match_points_ransacProjMatchPointsRansacProjMatchPointsRansacProjMatchPointsRansac with tuple_selecttuple_selectTupleSelectTupleSelectTupleSelect or with the HDevelop function subset. To enable bundle_adjust_mosaicbundle_adjust_mosaicBundleAdjustMosaicBundleAdjustMosaicBundleAdjustMosaic to determine which point pair belongs to which image pair, NumCorrespondencesNumCorrespondencesNumCorrespondencesNumCorrespondencesnumCorrespondences must contain the number of found point matches for each image pair.

The parameter TransformationTransformationTransformationTransformationtransformation determines the class of transformations that is used in the bundle adjustment to transform the image points. This can be used to restrict the allowable transformations. For TransformationTransformationTransformationTransformationtransformation = 'projective'"projective""projective""projective""projective", projective transformations are used (see vector_to_proj_hom_mat2dvector_to_proj_hom_mat2dVectorToProjHomMat2dVectorToProjHomMat2dVectorToProjHomMat2d). For TransformationTransformationTransformationTransformationtransformation = 'affine'"affine""affine""affine""affine", affine transformations are used (see vector_to_hom_mat2dvector_to_hom_mat2dVectorToHomMat2dVectorToHomMat2dVectorToHomMat2d), for TransformationTransformationTransformationTransformationtransformation = 'similarity'"similarity""similarity""similarity""similarity", similarity transformations (see vector_to_similarityvector_to_similarityVectorToSimilarityVectorToSimilarityVectorToSimilarity), and for TransformationTransformationTransformationTransformationtransformation = 'rigid'"rigid""rigid""rigid""rigid" rigid transformations (see vector_to_rigidvector_to_rigidVectorToRigidVectorToRigidVectorToRigid).

The resulting bundle-adjusted transformations are returned as an array of 3×3 projective transformation matrices in MosaicMatrices2DMosaicMatrices2DMosaicMatrices2DMosaicMatrices2DmosaicMatrices2D. In addition, the points reconstructed by the bundle adjustment are returned in (RowsRowsRowsRowsrows, ColsColsColsColscols). The average projection error of the reconstructed points is returned in ErrorErrorErrorErrorerror. This can be used to check whether the optimization has converged to useful values.

Execution Information

• Multithreading type: reentrant (runs in parallel with non-exclusive operators).
• Multithreading scope: global (may be called from any thread).
• Processed without parallelization.

Parameters

Example (HDevelop)

* Assume that Images contains the four images of the mosaic in the
* layout given in the above description.  Then the following example
* computes the bundle-adjusted transformation matrices.
From := [1,1,1,2,2,3]
To := [2,3,4,3,4,4]
HomMatrices2D := []
Rows1 := []
Cols1 := []
Rows2 := []
Cols2 := []
NumMatches := []
for J := 0 to |From|-1 by 1
    select_obj (Images, ImageF, From[J])
    select_obj (Images, ImageT, To[J])
    points_foerstner (ImageF, 1, 2, 3, 100, 0.1, 'gauss', 'true', \
                      RowsF, ColsF, _, _, _, _, _, _, _, _)
    points_foerstner (ImageT, 1, 2, 3, 100, 0.1, 'gauss', 'true', \
                      RowsT, ColsT, _, _, _, _, _, _, _, _)
    proj_match_points_ransac (ImageF, ImageT, RowsF, ColsF, RowsT, ColsT, \
                              'ncc', 10, 0, 0, 480, 640, 0, 0.5, \
                              'gold_standard', 2, 42, HomMat2D, \
                              Points1, Points2)
    HomMatrices2D := [HomMatrices2D,HomMat2D]
    Rows1 := [Rows1,subset(RowsF,Points1)]
    Cols1 := [Cols1,subset(ColsF,Points1)]
    Rows2 := [Rows2,subset(RowsT,Points2)]
    Cols2 := [Cols2,subset(ColsT,Points2)]
    NumMatches := [NumMatches,|Points1|]
endfor
bundle_adjust_mosaic (4, 1, From, To, HomMatrices2D, Rows1, Cols1, \
                      Rows2, Cols2, NumMatches, 'rigid', MosaicMatrices, \
                      Rows, Columns, Error)
gen_bundle_adjusted_mosaic (Images, MosaicImage, HomMatrices2D, \
                            'default', 'false', TransMat2D)

Result

If the parameters are valid, the operator bundle_adjust_mosaicbundle_adjust_mosaicBundleAdjustMosaicBundleAdjustMosaicBundleAdjustMosaic returns the value 2 (H_MSG_TRUE). If necessary an exception is raised.

Possible Predecessors

proj_match_points_ransacproj_match_points_ransacProjMatchPointsRansacProjMatchPointsRansacProjMatchPointsRansac, proj_match_points_ransac_guidedproj_match_points_ransac_guidedProjMatchPointsRansacGuidedProjMatchPointsRansacGuidedProjMatchPointsRansacGuided

Possible Successors

gen_bundle_adjusted_mosaicgen_bundle_adjusted_mosaicGenBundleAdjustedMosaicGenBundleAdjustedMosaicGenBundleAdjustedMosaic

See also

gen_projective_mosaicgen_projective_mosaicGenProjectiveMosaicGenProjectiveMosaicGenProjectiveMosaic

Module

Matching