Image taken at initial camera position
Image taken at current camera position
The difference between the intial image and an image which would be acquired at the pseudo-initial position of the camera, estimated by the computed motion parameters and the current image
Image taken at initial camera position
Image taken at current camera position
with marked detected feature points
with marked detected feature points
The accuracy of the parameter
estimation was evaluated by the comparison of the computed values with
the reference parameter values. Sets of corresponding feature pairs, evenly
distributed over the images, were manually detected
and the reference parameters
were computed by means of these sets. Illustrative examples of the parameter
comparison are summarized in the Table. Six situations
are introduced here, when images were blurred by the out-of-focus blur
(the manual defocus and the insertion of two different foreign objects
A and B) and differently rotated (small and big rotation,
approximately 6,2 and 10,8), respectively. The translations were present
in the camera motion too. The change of scale in the images is negligible
and the same in all cases. The translation parameters are given in pixels.
One pixel corresponds approximately to 0.4 cm (using the known size of
objects in the scene). In the last two rows there are means and standard
deviations (STDs) of the errors.
In all cases the estimates
corresponds well to the reference values and the STDs are small. Moreover
the differences between the computed and reference values are mostly below
the level of the discretization error. Even in the situations, when parts
of the scene are occluded by the foreign objects, the variations are negligible.
Table: Parameters of the
camera motion. Estimates of the rotation and of the translations in vertical
(V) and horizontal (H) directions and the difference between the computed
values and the reference ones. The reference parameter values are in the
parenthesis. Images were blurred (manual defocus, inserted objects - A,
B), rotated ( big angle, approximately 10,8, small
angle, approximately 6,2) and slightly translated.