16.23. disparitydebug

The disparitydebug program produces visualizable images from disparity maps created with parallel_stereo and stereo. These are named D_sub.tif, D.tif, RD.tif, and F.tif (see Section 19 for what each is).

The disparity map files can be useful for debugging because they contain raw disparity values as measured by the correlator; however they cannot be directly visualized or opened in a conventional image browser. The disparitydebug tool converts a single disparity map file into two normalized TIFF image files (*-H.tif and *-V.tif, containing the horizontal and vertical, or line and sample, components of disparity, respectively) that can be viewed using any image display program, including with the stereo_gui tool shipped with ASP (Section 16.72).

The disparitydebug program will also print out the range of disparity values in a disparity map, that can serve as useful summary statistics when tuning the search range settings in the stereo.default file (Section 14.4.2).

If the input images are map-projected (georeferenced), the outputs of disparitydebug will also be georeferenced.

16.23.1. Examples

disparitydebug run/run-D_sub.tif

View the obtained horizontal and vertical disparities with:

stereo_gui run/run-D_sub-H.tif run/run-D_sub-V.tif

Another example of using this tool (and a figure) is given in Section 6.1.8, when discussing how to examine a produced run.

16.23.2. Raw disparity extraction

To extract the horizontal and vertical bands from a disparity without normalization, run a command such as:

disparitydebug --raw run/run-F.tif

Invalid values are set to a no-data value (-1e+6) that is saved in the geoheader of the output files.

This shows the actual disparity values (not normalized), and whether they vary smoothly or are noisy. It is useful for inspecting the disparity before extracting interest point matches from it, such as in correlation-based alignment (Section 16.53.3.5).

This option is available in build 1/2026 and later.

View the obtained horizontal and vertical bands, colorized by value, with stereo_gui (Section 16.72, Section 16.72.5):

stereo_gui --colorbar              \
  --min -50 --max 50               \
  run/run-F-H.tif run/run-F-V.tif

The --min and --max options set the range of values for the colormap. Adjust them to bracket the actual disparity range, which is printed by disparitydebug.

16.23.3. Command-line options

-o, --output-prefix <string (default: “”)>

Specify the output file prefix. This is set automatically if not provided.

--raw

Save the raw disparity values without any normalization. Invalid pixels are set to no-data.

--save-norm

Save the norm of the disparity instead of its two bands.

--save-norm-diff

Save the maximum of norms of differences between a disparity and its four neighbors.

--normalization <(integer integer integer integer) (default = auto)>

Normalization range. Specify in the format: hmin vmin hmax vmax.

--roi <(integer integer integer integer) (default = auto)>

Region of interest. Specify in the format: xmin ymin xmax ymax.

-t, --output-filetype <string (default: tif)>

Specify the output file type.

--threads <integer (default: 0)>

Select the number of threads to use for each process. If 0, use the value in ~/.vwrc.

--cache-size-mb <integer (default = 1024)>

Set the system cache size, in MB.

--tile-size <integer (default: 256 256)>

Image tile size used for multi-threaded processing.

--no-bigtiff

Tell GDAL to not create BigTiff files.

--tif-compress <None|LZW|Deflate|Packbits (default: LZW)>

TIFF compression method.

-v, --version

Display the version of software.

-h, --help

Display this help message.