16.17. Image correlatorΒΆ
The parallel_stereo
program (Section 16.52) can
function purely as an image correlator, that is, it can find the
disparity between two given images without assuming any cameras are
present and without generating a point cloud.
This mode assumes that the images are already roughly aligned, up to a
translation. Hence, the images can be either raw but with no large
rotation/shear/scale differences, or mapprojected, or to be portions
of aligned images L.tif
and R.tif
(Section 19) as
created by ASP itself.
See also corr_eval
(Section 16.16) a program for estimating
the quality of the disparity at each pixel.
Usage:
parallel_stereo --correlator-mode <left image> <right image> \
<output prefix>
Example:
parallel_stereo --correlator-mode run/run-L.tif run/run-R.tif \
run_corr/run
This will create the filtered subpixel disparity
run_corr/run-F.tif
(Section 19).
If the expected search range is known, it can be specified with the option
--corr-search
(Section 17.2). Low resolution disparity computation
can be skipped with --corr-seed-mode 0
. These can be helpful if interest
point matching or low-res disparity are problematic.
If the options --num-matches-from-disparity
or
--num-matches-from-disp-triplets
are specified, dense matches from disparity
will be produced (Section 17). These can be used in bundle adjustment
(Section 12.2.4.2).
All the usual options of parallel_stereo
apply. See
Section 6 for a discussion regarding various quality vs
speed tradeoffs. Since the images are assumed to be aligned, the
program will set the alignment method to none
.
If desired to not use an initial low-resolution correlation, set
--corr-seed-mode 0
. To skip preprocessing (if invoked previously),
or to avoid subpixel refinement or filtering, use the options
--entry-point
and --stop-point
.